Nurs 208
Class 1: Endocrine system
The endocrine system use chemicals (hormones) to communicate. Requires
interstitial fluid and bloodstream for the transmission of signals and
receptors for signal recognition. Response time is slow (seconds to hours or
day). Duration of action is longer (seconds to days).
Difference between exocrine and endocrine glands
Exocrine glands: Secretion through ducts into the body cavity, lumen, or
surface of the body. Including sweat glands, gastric glands, and mucosal
gland, etc. Secrete non-hormonal substances.
Endocrine glands: Secrete their chemical products into the interstitial fluid
surrounding the cells (no duct) and can be carried into targeting cell
through blood circulation. All endocrine glands and hormone-secreting cells
together constitute the endocrine system.
1)List the functions of the endocrine system
• Regulation of growth and development
• Maintenance of the optimum internal environment, such as the water
and electrolytes balance, in order to sustain the optimum body
function
• Initiating and maintaining the reproductive system
• Hormones act on the target cells by controlling:
- Rates of enzymatic reactions
- Transport of ions and molecules across cell membranes
- Gene expressing and protein synthesis
2) Define hormones
Hormones are chemical signal produced by a cell, tissue, or organ released
into the blood and carried to another organs (or targets). Able to produce a
specific response in distant target organ at a very low concentration. Many
type of cells & tissues NOT classically thought of as endocrine in nature also
produce hormones. Intercellular communication involving the production of
hormones (chemical signals) can act any of (or all) the three ways:
Endocrine (distant tissues)- Chemical signals produced by cells and released
into blood circulation. Chemical signals bind to distant target cells to exert
the action.
Paracrine (neighboring tissues)- Chemical signals produced by cells and
released into extracellular space. Chemical signals bind to neighboring
target cells in the same organ.
Autocrine (same cell)- Chemical signals produce by cells and release into
extracellular space. Chemical signal bind to the same cell that release the
signaling molecule.
To ensure paracrine and autocrine signals to be delivered to the proper
targets only, the spread or diffusion of their chemical signals must be
limited. This can be accomplished by:
→ Rapid endocytosis of the chemical signals by neighboring cells
→ Rapid destruction of the chemical signals by extracellular enzymes
→ Rapid immobilization of the chemical signals by extracellular matrix
Hormones in the bloodstream are generally degraded into inactive
metabolites by enzymes located in the liver and kidneys. The time required
to reduce the concentration of hormone in the bloodstream by half is known
as the hormone’s half-life. Hormone that binds to membrane receptor is
brought into the cell by endocytosis and digested by lysosomes and
intracellular enzymes
3) Describe how hormones are classified
Chemical composition- Hormones of peptides and proteins (peptide
hormones e.g. insulin). Hormones derived from amino acids (amine
hormones e.g. Epi). Hormones derived from cholesterol (steroid hormones
e.g. estrogen)
Physical properties- Lipid soluble (e.g. steroid hormones), Water soluble
(e.g. Epi), Gases (e.g. NO).
4) Identify the general relationships between the hypothalamus, the
pituitary glands and the peripheral endocrine glands in the control of
hormone secretion
Tropic hormone is a hormone controls the secretion of another endocrine
gland to produce hormone. Three important integrating centers that control
the secretion of hormones:
Hypothalamic region→ Tropic signals from CNS
Anterior pituitary region→ Tropic signals from hypothalamic tropic
hormones
Endocrine gland→ Tropic signals from anterior tropic hormones
5) Describe how different hormones acting on the same target cell influence
the cell response via synergistic, antagonistic, or permissive interactions
Synergism: Combined effect is greater than the sum of individual effects
Permissiveness: Need second hormone to get full effect
Antagonism: One substance opposes the action of another
Class 2: Endocrine system
The hypothalamus is located in the diencephalon (compose of thalamus,
hypothalamus, and pineal gland). Located below the thalamus and above the
brainstem. It is the major link between the nervous and endocrine systems.
Hypothalamic-pituitary axis contains 3 components: Hypothalamus;
pituitary; and target organs. The hypothalamus controls an array of
hormonal systems through the pituitary gland. Hormones released by the
pituitary gland then trigger the cellular responses of the target organs. The
pituitary gland is a pea-shaped structure that attaches to the hypothalamus
by a stalk with two anatomically and functionally separate portions: the
anterior pituitary (adenohypophysis) and the posterior
pituitary(neurohypophysis).
1) Describe the control of endocrine secretion by the hypothalamic-pituitary
axis
Hypothalamus releases tropic hormones that regulate the release of
hormones by the pituitary gland. Hypothalamus secretes 5 well known
releasing hormones which stimulate secretion of anterior pituitary
hormones:
Growth hormone-releasing hormone (GHRH)- Also known as somatocrinin.
It simulates secretion of growth hormone (GH)
Thyrotropin-releasing hormone (TRH)- it stimulates secretion of thyroidstimulating hormone (TSH)
Corticotropin-releasing hormone (CRH)- it stimulates secretion of
adrenocorticotropic hormone (ACTH) – also known as corticotropin
Prolactin-releasing hormone (PRH)- it stimulates secretion of prolactin
(PRL)
Gonadotropin-releasing hormone (GnRH)- it stimulates secretion of folliclestimulating hormone (FSH) and luteinizing hormone (LH)
Hypothalamus also secretes 2 inhibiting hormones which suppress secretion
of anterior pituitary hormones:
Growth hormone-inhibiting hormone (GHIH)- Also known as somatostatin.
It suppresses secretion of growth hormone (GH)
Prolactin-inhibiting hormone (PIH)- It is actually the dopamine (function as
a hormone as well as a neurotransmitter). It suppresses secretion of
prolactin (PRL)
2) Describe the cellular responses elicited by some of the hormones
5 types of anterior pituitary cells that produce their corresponding
hormones:
Somatotrophs- Secrete growth hormone (GH). It is also known as human
growth hormone(hGH) or somatotropin. Stimulates general body growth
and regulates metabolism.
Thyrotrophs- Secrete thyroid-stimulating hormone (TSH). Also known as
thyrotropin. Controls the secretions and other activities of the thyroid
gland.
Gonadotrophs- Secrete two gonadotropins: follicle-stimulating hormone
(FSH) and luteinizing hormone (LH). Stimulate the testes to produce sperm
and to secrete testosterone in men. Stimulate the ovaries to mature oocytes
(eggs) and to secrete estrogens and progesterone in women.
Lactotrophs- Secrete prolactin (PRL) which initiates milk production in the
mammary glands.
Corticotrophs- Secrete adrenocorticotropic hormone (ACTH). Also known as
corticotropin. Stimulates the adrenal cortex to secrete glucocorticoids such
as cortisol.
3) Describe the location, histology, hormones, and functions of the thyroid
gland, parathyroid glands
The thyroid is located just inferior to the larynx (voice box) and on top of
the trachea. It has right and left lateral lobes and is connected by an
isthmus. It has the ability to stores its secretory product in large quantities;
Sufficient for about 100 days of supply. Thyroid gland secretes three
hormones:
Thyroxine (T4) → Also known as tetraiodothyronine. It contains four atoms
of iodine. T4 normally is secreted in greater quantity than T3 → But T3 is
several times more potent. After T4 enters a body cell, most of it is
converted to T3 by removal of one iodine.
Triiodothyronine (T3) → It contains three atoms of iodine. T3 and T4 are
referred to as thyroid hormones and are produced by the follicular cells
within the thyroid gland.
Calcitonin (CT)→ It is a type of peptide hormones produced by the
parafollicular cells within the thyroid gland.
Functions
Thyroxine (T4) and Triiodothyronine (T3):
1. Increase basal metabolic rate (BMR) by increasing the rate of cellular
metabolism involving carbohydrates, lipids, and proteins. Increase the
rate of ATP production and consumption Increase the number and
activity of mitochondria in cells. When BMR increases, more heat is
given off, and body temperature rises, a phenomenon called the
calorigenic effect.
2. Enhance actions of catecholamines; Thyroid hormones up-regulate βadrenergic receptors. Thereby, promoting sympathetic responses and
increased heart rate, more forceful heartbeats, and increased blood
pressure.
3. Regulate development and growth of nervous tissue necessary for the
development of the nervous system which promote synapse formation,
myelin production, and growth of dendrites. Deficiency of thyroid
hormones during fetal development, infancy, or childhood causes
severe mental retardation and stunted bone growth.
Calcitonin: Decreases the plasma level of calcium by inhibiting
the action of osteoclasts. Osteoclasts are cells found in bone that break
down bone extracellular matrix. Calcitonin lowers the amount of blood
calcium and phosphates by inhibiting bone resorption (breakdown of bone
extracellular matrix) by osteoclasts and accelerating uptake of calcium and
phosphates into bone extracellular matrix.
Control of thyroid hormone secretion
Low plasma levels of T3 and T4 or low metabolic rate: → Stimulate the
hypothalamus to secrete thyrotropin-releasing hormone (TRH). TRH enters
the hypothalamic-hypophyseal portal system and flows to the anterior
pituitary, where it stimulates thyrotrophs to secrete TSH. TSH stimulates
virtually all aspects of thyroid follicular cell activity and causes the
production and the release of T3 and T4 into the blood stream. An elevated
level of T3 inhibits release of TRH and TSH (negative feedback inhibition).
Class 3: Endocrine system
1) Describe the location, histology, hormones, and functions of the adrenal
gland and pancreatic islets (ovaries and testes will be covered in
reproduction module)
The adrenal gland also known as suprarenal glands is a flattened pyramidal
shape structure lies superior to each kidney in the retroperitoneal space. It
has 2 functionally distinct regions: Peripherally located adrenal cortex
comprising 80–90% of the gland and the centrally located adrenal medulla
comprising a smaller portion of the gland. Adrenal glands are innervated by
the sympathetic nervous system only. Adrenal cortex secretes steroid
hormones that are essential for life. Essential for electrolyte balance
(particular for Na+). Complete loss of adrenocortical hormones could lead to
death due to dehydration and electrolyte imbalance and requires hormone
replacement therapy. Adrenal medulla secretes 3 catecholamine hormones:
epinephrine, norepinephrine, and a small amount of dopamine.
Adrenal cortex: Subdivided into 3 zones:
Outer zone→ Secretes hormones called mineralocorticoids. Affect mineral
homeostasis
Middle zone→ Secretes glucocorticoids, primarily cortisol. Affect glucose
homeostasis
Inner zone→ Synthesize small amounts of weak androgens (Steroid
hormones that have masculinizing effects).
Adrenal medulla: With hormone-producing cells called chromaffin cells,
produce mainly 80% epinephrine and 20% norepinephrine.
Functions
Mineralocorticoids (aldosterone)→ It regulates homeostasis of two mineral
ions: Sodium ions (Na+) & Potassium ions (K+) through the renin–
angiotensin–aldosterone (RAA) pathway. RAA pathway regulates the
homeostasis of blood volume, blood pressure, plasma pH, and electrolytes.
Glucocorticoids→ Regulate metabolism and resistance to stress. 3 main
hormones: Cortisol, corticosterone, and cortisone. Cortisol is the most
abundant and accounting for about 95% of glucocorticoid activity. The main
hormonal actions of glucocorticoids include: 1)breaking down proteins
mainly from the muscles into forming amino acids and ATP synthesis,
2)Stimulate liver cells to convert certain amino acids or lactic acid to
produce glucose (gluconeogenesis), 3)Stimulate the breakdown of
triglycerides and release of fatty acids from adipose tissue into the blood
(lipolysis), 4)Provide resistance to stress such as: Increase glucose levels to
produce ATP to combat a range of stresses, such as exercise, infection,
fasting, trauma, etc., 5) Inhibit white blood cells that participate in
inflammatory responses (i.e. anti-inflammatory); Anti-inflammatory effect
also retards tissue repair and slow wound healing, 6)High doses of
glucocorticoids depress immune responses; Glucocorticoids are prescribed
for organ transplant recipients to suppress tissue rejection by the immune
system.
Epinephrine and norepinephrine are the 2 major hormones produced by
chromaffin cells which increase Fight-or-flight response.
Control of glucocorticoid secretion
Through negative feedback system. When levels of glucocorticoids (mostly
cortisol) is low, corticotropin-releasing hormone (CRH) is secreted by
hypothalamus. CRH (and a low level of cortisol) promotes the release of
adrenocorticotropic hormone (ACTH) from the anterior pituitary. ACTH
enters the adrenal cortex where it stimulates glucocorticoid secretion.
When glucocorticoids level is back to normal, negative feedback is removed
and CRH secretion diminished (no more glucocorticoids are released).
The pancreas is both an endocrine gland and an exocrine gland located in
the curve of the duodenum. 99% of the exocrine cells of the pancreas are
arranged in clusters called acini and endocrine tissues called pancreatic
islets (islets of Langerhans) are enclosed by the acini.
Hormone secretion and function of the pancreases
Alpha or A cells: are about 17% of pancreatic islet cells and secrete
glucagon. Glucagon increases plasma glucose levels by mainly converting
glycogen into forming glucose. Low plasma level of glucose stimulates the
release of glucagon.
Beta or B cells: are about 70% of pancreatic islet cells and secrete insulin.
Insulin decreases plasma glucose levels by facilitating the diffusion of
glucose into cells, speed conversion of glucose into forming glycogen
(glycogenesis) and also enhance synthesis of fatty acids (lipogenesis).
Delta or D cells: about 7% of pancreatic islet cells and secrete somatostatin.
Somatostatins inhibit both insulin and glucagon release, may slow
absorption of nutrients from the gastrointestinal tract and reduce gastric
acid secretion.
F cells: are a small percentage of pancreatic islet cells and secrete
pancreatic polypeptide. Pancreatic polypeptide is shown to decrease food
intake and plasma levels decrease during fasting which is elevated after
meal.
2) Describe the properties, functions, location, and hormones of the pineal
gland and thymus
The pineal gland secretes melatonin. Synthesis and release of melatonin are
stimulated by darkness but inhibited by light.
The thymus is located behind the sternum between the lungs and rests on
the pericardium. It is a lymphoid organ for the immune system.
Hormones produced by the thymus include thymosin, thymic humoral factor
(THF), thymic factor (TF), and thymopoietin. The main function is to
1)promote the maturation of T cells (a type of white blood cell) called T
cells because they mature in the thymus, 2)Trigger an immune response
that does not involve antibodies, 3)Involves the activation of phagocytes and
antigen specific cytotoxic T cells.
3) Describe the body’s response to stress
Fight or flight responses
Class4: Cardiovascular system
1) Describe the anatomical location and structure of the heart
It is located in the mediastinum between the lungs, from the 2nd to 5th
intercostal space.
The heart is enclosed by the pericardium. It consists of an outer fibrous
pericardium and an inner serous pericardium. The serous pericardium has 2
layers: 1. Visceral & 2. Parietal. The visceral and parietal layers are
separated by the serous cavity, a fluid- filled space.
The layers of the heart wall are: Epicardium (made up of 2 layers: visceral
mesothelium and parietal connective tissue); contains blood vessels and
lymphatics that supply the myocardium, Myocardium (consists of muscle
tissue); makes up 95% of heart wall, Endocardium (consists of endothelium
and connective tissue); provides a smooth lining for the chambers of the
heart and covers the valves of the heart.
The external surface of the heart includes the auricle (small pouches on the
anterior surface of each of the atrium; slightly increase the capacity of each
atrium), the coronary sulcus (groves that contain blood vessels and fat)
between the atrium and the ventricle and the anterior and posterior
interventricular sulcus.
The heart has 4 chambers light and left atrium and ventricle. The right side
for deoxygenated blood and left for oxygenated. The right ventricle forms
most of the anterior surface of the heart and is separated from the left
ventricle by interventricular septum.
The fibrous skeleton is connective tissue supporting the four valves of the
heart and fused to one another. It serves as foundation for heart valve
attachment, it is a point of insertion for cardiac muscle bundles, prevents
overstretching of the heart valves and acts as an electrical insulator.
2) Describe the valves of the heart
The heart contains valves that open and close passively in response to
pressure. There are 2 sets: Atrioventricular (AV) valves ( (R) Tricuspid
valve & (L) Bicuspid valve), Semilunar (SL) valves ( (R) Pulmonary valve &
(L) Aortic valve). Valves have thin leaflets that are anchored by collagenous
fibres called chordae tendineae attached to papillary muscles on the
ventricular floor.
3) Describe the structural characteristics of cardiac muscle tissue and the
electrical conduction system of the heart
The cardiac muscle tissue forms two separate networks that function in the
heart: the atria and the ventricular networks. The cardiac muscle fibres in
the myocardium are striated branching cells with either one or two nuclei
and the ends of the adjacent cardiac muscle fibres are connected by
intercalated disks which contain desmosomes that function to hold the
fibers together and have gap junctions that enables action potentials to
spread quickly from cell to cell and allows the muscle to contract as a unit.
Electrical conduction system- Goal: ensure chambers of the heart contract in
a coordinated manner.
Components: sinoatrial node, atrioventricular node, atrioventricular bundle
(bundle of his), right and left bundle branches, purkinje fibers.
Normal conduction pathway is SA node, AV node, bundle of His, R&L
branches, purkinje fibers. One unique characteristic of cardiac muscle
fibers: autorhythmic (they can self excite). SA node is considered the
natural pacemaker of the heart as it is the area that generates the action
potentials most often.
Class 5: Cardiovascular system
There are five main types of blood vessels:
Arteries- consists of tunica intima (responsible for maintaining the
elasticity and contractility of the artery), tunica media, & tunica externa.
The large arteries are called elastic or conducting arteries and medium
sized arteries are called muscular or distributing arteries. Arteries
anastomosis can occur where the distal ends of two or more of vessels unite
and an alternative route is available for circulation and that's called
collateral circulation.
Arterioles- small arteries that deliver blood to the capillaries through the
action of constriction and dilation.
Capillaries- microscopic blood vessels through which materials are
exchanged between the blood and tissue cells. Some are continuous and
some are finished striated.
Venules- vessels that continue from capillaries and merge to form the veins.
Veins- consists of tunica intima, tunica media, & tunica externa. They're
defined as blood reservoirs because they can hold a large amount of blood.
1) Identify the aorta and its branches
It is the aorta is the largest artery in the body and all systemic arteries
branch from it. It is divided into four main divisions:
Ascending Aorta: Coronary arteries- it starts from the aortic valve, and it
ends at the aortic arch at the level of the sternal angle and the right and left
coronary arteries branch off the ascending aorta and travel to the heart. The
posterior interventricular branch is the right coronary artery that supplies
both ventricles. The marginal branch supplies the right ventricle as well.
The anterior interventricular branch supplies both ventricles and the
circumflex branch supplies the left atrium and the left ventricle.
Aortic Arch: it is a continuation of the ascending aorta and it begins at the
level of the sternal angle and it ends at the level of the intervertebral disk
between the fourth and fifth thoracic vertebrae. The three major branches
that come off the aortic arch from right to left are the brachiocephalic
trunk, the left common carotid artery, and the left subclavian artery/
axillary artery. The brachiocephalic trunk divides at the right
sternoclavicular joint to form the right subclavian artery and the right
common carotid artery. The right common carotid artery further divides
into the external and the right internal carotid arteries at the superior
border of the larynx. The internal carotid arteries travels through the neck
and they enter the skull through the carotid canal within each temporal
bone and supply the structures within the skull; each internal carotid artery
branches to form an internal cerebral artery and a middle cerebral artery
which supplies blood to parts of the brain and the external carotid arteries
extend along the lateral surface and terminate as two arteries nearer the
temporomandibular joint. The left common carotid artery divides into the
same branches as the right common carotid artery. The left subclavian
artery distributes blood to the left vertebral artery and vessels of the left
upper limb.
The circle of Willis is as described is a circle or a ring of blood vessels
formed by three anastomoses to the brain.
Thoracic Aorta- also known as descending aorta. It’s a continuation of the
aortic arch and it ends at the abdominal aorta between T12 and L1. It has
visceral branches, which go to the viscera which are the pericardial, the
bronchial, the oesophageal and the mediastinal arteries that supply those
areas and parietal branch to the body wall structures and those supply the
posterior intercostal, the subcostal and the superior phrenic arteries.
Abdominal Aorta- it’s a continuation of the thoracic aorta after it passes
through the diaphragm. It begins at the diaphragm, and it ends at the level
of the fourth lumbar vertebrae where it divides into the right and left
common iliac arteries. The visceral branches are unpaired, and they supply
the celiac trunk, the superior mesenteric and the inferior mesenteric artery
and the visceral branches are paired, and they supply the super renal, the
renal and the gonad arteries. The parietal branches are also unpaired, and
they supply the median sacral artery, and the parietal branches are paired
and supply the inferior phrenic and lumbar artery. The common iliac
arteries further divide into the external and the internal iliac arteries. The
internal iliac arteries carry most of the blood supply to the pelvic viscera
and the wall. The external iliac artery becomes the femoral artery and
descends along the middle of the anterior two thirds of the thigh and travels
to the posterior thigh becoming the popliteal artery as it enters the
posterior knee area, and it divides into the anterior in the posterior tibial
arteries. The anterior tibial artery, travels to the anterior surface of the leg
and it descends to the ankle where it becomes the dorsalis pedis artery. The
posterior tibial artery descends along the posterior aspect of the leg and
terminates at the ankle where it divides into the medial and lateral plantar
arteries. The fibula or the peroneal artery branches off the posterior tibial
artery and travels down the lateral side of the leg to the foot.
2) Identify the major veins that drain blood from the head, upper limbs,
abdomen and pelvis
Veins that accompany arteries usually have the same name as the arteries.
The blood draining from the head passes into the internal jugular the
external jugular and the vertebral veins and then drains into the
brachiocephalic veins. They drain into the dural venous sinuses and then
into the internal jugular vein. The internal jugular vein runs lateral to the
internal carotid and the common carotid arteries, and it drains the brain,
the meninges, the bones of the cranium, the muscles and tissues of the head
and neck, the nasal cavity, the superior lateral and medial aspects of the
cerebrum, the skull bones, the cerebellum, the orbits, and the superior
aspect of the brain stem. The external jugular veins are superficial veins
descending along the lateral surface of the neck and they drain the scalp and
the skin of the head, neck muscles of the face and the neck and the oral
cavity and the phoenix. The vertebral veins descend through the transverse
forum and out of the vertebral column with the vertebral arteries and they
drain the cervical vertebrae, their cervical spinal cord in the meninges and
some deep muscles in the neck.
The limbs have superficial and deep veins. The major superficial veins are
the basilic and cephalic veins; they're larger than deep veins and they
return most of the blood from the upper limbs. The major deep veins are the
radial and the ulnar veins in the forearm and they merge to form brachial
veins. Those brachial veins ascend the arm and join with the basilic vein to
form the axillary vein and the axillary vein becomes the subclavian vein.
The deep veins run with arteries. The right subclavian vein drains the skin,
the muscles, the bones of the arms, the shoulders, the neck, and the
superior thoracic wall and is the preferred site for central line placement.
The axillary veins drain the skin, the muscles, the bones of the arm, the
axilla, the shoulder and the superior lateral chest wall. The brachial veins
drain the muscles and bones of the elbow and the brachial region. The ulnar
veins drain muscles, bones and skin of the hand in the muscles of the medial
aspect of the forearm. The radial veins drain muscles and bones of the
lateral hand and forearm. The cephalic vein travel along the anterior lateral
surface of the entire limb and merge with the axillary vein inferior to the
clavicle and it drains the skin and superficial muscles of the lateral aspect
of the upper limb. The basilic veins travel along the medial aspect of the
forearm and the interior surface of the arm, and they drain the skin and the
superficial muscles of the medial aspect of the upper limb and the medial
cubital vein is the preferred site for injection, transfusion and removal of
any blood samples. The medial antebrachial veins drain the into the skin
and the superficial muscles of the palm and the anterior surface of the
upper limb.
The brachiocephalic veins drain some portions of the thorax but most of the
thoracic structures are drained by sort of something called the azygos
system; a network of veins.
The internal and the external iliac veins and the pelvis merge to form the
common iliac veins that unite to form the inferior vena cava. The lumbar
veins, the gonadal veins, the renal veins, the super renal veins and the
hepatic veins drain directly into the inferior vena cava. The veins draining
the stomach, the intestines, the spleen, the pancreas and the gallbladder do
not drain directly into the inferior vena cava but are involved with the
hepatic portal circulation. The major veins of the hepatic portal circulation
are the inferior mesenteric vein, the splenic vein, the superior mesenteric
vein and the hepatic portal. The inferior mesenteric vein drains blood from
the large intestine, and it joins the splenic vein which carries blood from the
stomach, the pancreas and the spleen. The superior mesenteric vein drains
blood from the small intestine and merges with the splenic vein to form
hepatic portal vein that carries the nutrient rich blood to the liver and the
liver is then drained by the hepatic veins that empty into the inferior vena
cava.
3) Identify the components of the azygos system of veins
It consists of three main components of veins that drain into the superior
vena cava that run on either side of the vertebral column.
Azygos veins- drain the right side of the thoracic wall, the thoracic viscera
and the posterior abdominal wall.
Hemiazygos veins- drains the left side of the of the thoracic wall, the
thoracic viscera and the left posterior abdominal wall.
Accessory homozygous- drain the left side of the upper thoracic wall and the
serous viscera.
Because they form an anastomosis with the large veins draining the lower
limbs in the abdomen and the inferior vena cava they can serve as a bypass
for the inferior vena cava.
4) Identify the principal superficial and deep veins that drain the lower
limbs
The major superficial veins in the lower limbs are the great saphenous vein
and the small saphenous veins. The great saphenous vein is the longest vein
in the body that runs along the medial surface of the leg and the thigh and
contains 10 to 20 valves. The small saphenous vein ascends along the lateral
posterior surface of the leg and varicose veins are the most common in
those.
The deep veins of the leg ascend in the leg adjacent to the arteries of the
same name. The anterior and posterior tibial veins are paired, and they
ascend in the interior and the posterior leg and they unite inferior to the
popliteal fossa to form the popliteal vein which ascend along the posterior
surface of the knee and they become the, the femoral vein. The paired fibula
or peroneal veins travel superior only along the lateral leg and join the
posterior tibial veins.
Class 6: Cardiovascular system
Identify the components of the lymphoid (lymphatic) system
Structure
Lymph or lymph plasma
Lymphatic vessels
Lymphoid organs & tissue
Red bone marrow
Function
Initiates immune responses
Collection of excess interstitial fluid
Delivery of dietary lipids & lipid-soluble vitamins ADEK
Lymphatic vessels follow the pathway of the veins in the body, and they
have a similar structure, but they have thinner walls and more valves than
veins do. They flow in a chain of lymph nodes where lymph plasma is
filtered within a specific body region and the vessels exit that last lymph
node in each chain and merge to form lymphatic trunks.
Lymphatic capillaries are found throughout the body except in avascular
tissue; the CNS portions of the spleen and bone marrow and they lie near
blood capillaries. They have a slightly larger diameter than blood capillaries
and they have overlapping endothelial cells which work as the one-way
valves for fluid to enter the lymphatic capillaries. They're closed at one end
and have anchoring filaments that attach the endothelial cells to the
surrounding tissue. The interstitial fluid drains into the lymphatic
capillaries, thus forming the lymph. The lymphatic capillaries merge to form
larger vessels called lymphatic vessels and they transport the lymph in into
and out of the structures called the lymph nodes.
Routes of drainage
Lymph trunks merge to form either thoracic duct or the right lymphatic duct
and all plasma returns to the blood stream through the thoracic duct and the
right lymphatic duct. The principal lymph trunks formed from the exiting
vessels of lymph nodes are the lumbar trunk (which drains the lower limbs,
the wall and the viscera of the pelvis, the kidneys, the super renal glands
and the abdominal wall), the intestinal lymph trunk (trunk which drains the
stomach, the intestines, the pancreas, the spleen and part of the liver), the
broncho mediastinal trunk (which drains the thoracic wall, lungs and
heart), the subclavian trunk (drains the upper limbs) and the jugular trunk
(drains the head and the neck). In the abdominal area the lymphatic trunk
stay merged together to form a sac like reservoir called the cisterna chyli
which drains the lymph plasma from the entire body below the diaphragm.
The right lymphatic duct drains lymph from the right upper side of the body
into the venous blood at the junction of the right internal jugular and the
subclavian veins. The thoracic begins at the cisterna chyli and continues
superiorly and is the main collecting duct for the lymphatic system.
Formation and flow of lymph
The lymph plasma is formed from blood plasma, and it’s filtered out to the
interstitial places due to osmotic pressure where it is called interstitial fluid
and the filtered into the lymphatic capillaries and now we call it lymphatic
plasma or lymph plasma.
Interstitial spaceslymph capillarieslymph vessels lymph trunks or
ductsinternal jugular & subclavian veins.
The flow of lymph is as a result of muscular skeletal muscle contractions
and respiratory movements.
Lymphoid organs
They're located throughout the body. The lymphoid organs contain actual
lymphoid tissue and they're surrounded by a capsule, and they are the
thymus, the lymph nodes and the spleen. The lymphoid tissue is specialised
reticular connective tissue that contains many lymphocytes. The lymphoid
organs are subdivided into primary lymphoid organs and secondary
lymphoid organs according to function. The primary lymphoid organs are
the red bone marrow and the thymus; they contain stem cells that produce
lymphocytes and they're the sites where lymphocytes become
immunocompetent. The thymus gland lies between the sternum and the
large blood vessels above the heart, and it functions in conjunction to help
with the immunity as the site of the T-cell maturation. the secondary
lymphoid organs, are the lymph nodes, the spleen and the lymphoid
nodules.
Thymus
It is bi-lobed and is located in the mediastinum between the sternum and
the superior vena cava and the two lobes of the thymus are held together by
a layer of connective tissue and each lobe is surrounded by a connective
capsule and the trabecular are extensions of the capsule that divide each
lobe into lobules and each lobule has an outer cortex in an entire medulla.
Immature t cells migrate to the thymus from their origin, the red bone
marrow to mature and once they become mature or immunocompetent, they
leave the thymus and they migrate to lymph nodes, the spleen and other
lymphoid tissues where they begin their role.
Structure of a Lymph Node
They are located along lymphatic vessels and are present throughout the
body and they're generally clustered in groups. Their main responsibility is
to filter lymph. They contain t cells, Macrophages, follicular dendrite cells,
B cells and are the site of proliferation. The lymph plasma enters each node
through afferent lymphatic vessels and exits through efferent lymphatic
vessels which is away from the centre. Foreign substances or pathogens that
are filtered by the lymph nodes are trapped by nodal reticular fibres and
those macrophages then destroy some foreign substances and cells by
phagocytosis and then the lymphocytes bring about the destruction of other
cells by initiating that immune response.
Spleen
It is the largest lymphoid organ and it's located posterior and lateral to the
stomach in the left upper quadrant. It has a hilum through which the splenic
artery enters, and the splenic vein and afferent lymphatic vessels exit. It is
encapsulated with extensions of the capsule forming the trabecula. The
capsule, the trabecula, the reticular fibres and their reticular cells (reticular
cells are just specialised fibroblasts.) form a network for two substances or
sections called the White Pulp and the Red Pulp. The white pulp resembles
lymphoid nodules in the lymph nodes, and it contains lymphocytes and
macrophages, and they surround branches of the splenic artery called
central arteries. The B and the T cells within the white pulp initiate the re
immune responses to bloodborne pathogens while the macrophages destroy.
The red pulp contains a blood-filled sinus and splenic cords. The splenic
cords contain red blood cells, macrophages which remove older damaged
blood cells and platelets lymphocytes, plasma cells and granular sites,
which attack pathogens; it also stores about a third of the body's platelets
and produces blood cells in the foetus.
Lymph nodules
The lymphoid nodules are egg shaped clusters of lymphoid tissue, but
they're not encapsulated. It contains Mucosa-associated lymphoid tissue
(MALT) and they are small, single lymphoid nodules and they're scattered
throughout connective tissue of mucous membranes of the GI the
respiratory, the urinary and the reproductive tract. There are also large
groups of lymphoid nodules divided into Peyer’s Patches and Tonsils.
Payer’s patches are generally located in the ilium of the small intestine, the
appendix. Tonsils are multiple aggregations of large lymphatic nodules that
are embedded in a mucous membrane at the junction of the oral cavity and
the pharynx. there's five tonsils there in particular: one
pharyngeal(adenoid), 2 palatine and 2 lingual; they are located in a site to
protect against the invasion of foreign pathogens or foreign substances and
they also participate in the immune responses by producing lymphocytes
and antibodies.
Class 7: Cardiovascular system
1) Know the ionic basis of an action potential for the contractile myocyte
There are 5 phases of depolarization & repolarization of the cardiac
contractile myocyte:
Phase 0 → Known as rapid depolarization phase. Occurs when spontaneous
gradual depolarization of the pacemaker cells reaches the threshold; with
influx of Na+ through the fast Na+ channels (voltage-gated Na+ channels).
Phase 1→ Known as early repolarization phase; With rapid inactivation of
the fast Na+ channels; together with the activation of the transient outward
K+ current (fast activated and inactivated K+ channels) i.e. Brief efflux of
K+.
Phase 2→ Called the plateau phase; It is the balance between K+ efflux and
Ca2+ influx. K+ efflux: Through K+ channels (also known as delayed
rectifier K+ channels). Ca2+ influx: Through L-type (long-lasting) Ca2+
channels. Duration of phase 2 ≈ 175 msec.
Phase 3→ It is the repolarization phase; Starts with the inactivation of the
L-type Ca2+ channels with the continuation on the efflux of K+ i.e. Inside of
the cell membrane becomes progressively more negative. Duration of phase
≈ 75 msec.
Cell is in refractory (unexcitable) during phases 0,1,2, & part of phase 3.
Phase 4→ Restoration of ionic concentrations; Concentration of Na+ and K+
return to their resting state by Na+-K+ pumps (Na+-K+ ATPase) With 2 K+
entering & 3 Na+ leaving the cell. Ca2+ move out by both the Na+-Ca2+
exchangers and ATP-driven Ca2+ pumps; 3Na+ in 1Ca+ out.
2) Know how the ECG is generated and describe what each of the ECG
components represent
ECG is a graphic recording/display of the biopotentials generated by the
myocardium during the cardiac cycle. It reflects the rhythmic electrical
events of depolarization and repolarization wave (action potential),followed
by mechanical events of contraction and relaxation of the atria and
ventricles.
Depolarization- The ECG tracing shows an upward deflection when the
depolarization wave (+ve wave) flow towards the +ve recording electrode.
The larger the tissue mass involved in depolarization, the higher the
amplitude of the deflection.
Repolarization- The ECG tracing shows a downward deflection when the
repolarization wave (-ve wave) flow towards the +ve recording electrode.
The larger the tissue mass involved in repolarization, higher the amplitude
of the deflection.
P wave: depolarization of atria
QRS complex: depolarization of ventricles
T wave: repolarization of ventricles
U wave: unknown, possible repolarization of papillary muscles or delayed
repolarization of Purkinje fibers.
Standard position (placement) of the ECG recording electrodes:
Normally, ECG contains 6 limb leads (I, II, III, aVR, aVL, and aVF) and 6
chest leads (V1 to V6). Lead aVR, aVL, aVF, and V1 to V6 are also referring to
as unipolar ECG. Leads I. II, & III are also know as bipolar limb leads.
Ground electrode (RL) is always connected to the right leg.
Bipolar limb leads:
Lead I: -ve lead (RA) at right arm, +ve lead (LA) at left arm
Lead II: -ve lead (RA) at right arm, +ve lead (LL) at left leg
Lead III: -ve lead (LA) at left arm, +ve lead (LL) at left leg
These connections are arbitrarily chosen such that the QRS complexes will
be upright in all 3 limb leads in most normal individuals.
Unipolar limb leads (augmented limb leads):
aVR: Right arm (RA) as +ve, all other leads (LA & LL) serve as –ve electrode
aVL: Left arm (LA) as +ve, all other leads (RA & LL) serve as –ve electrode
aVF: Left leg (LL) as +ve, all other leads (RA & LA) serve as –ve electrode
Unipolar chest leads (precordia leads):
V1: In the 4th intercostal space (between ribs 4 and 5) just to the right of
the sternum
V2: In the 4th intercostal space (between ribs 4 and 5) just to the left of the
sternum
V3: Between leads V2 and V4
Unipolar chest leads (precordia leads):
V4: In the 5th intercostal space (between ribs 5 and 6) in the mid-clavicular
line (clavicle or collarbone).
V5: Horizontally even with V4, in the left anterior axillary line (midway
between the middle of the clavicle and the lateral end of the clavicle).
V6: Horizontally even with V4 and V5 in the mid-axillary line.
Class 8: Cardiovascular system
1) Explain the events occurring during each phase of the cardiac cycle
Start of atrial depolarization (P wave) →Atria are still in full relaxation
Atria depolarization complete →Atrial contraction in progress
Start of ventricular depolarization (QRS complex) →Ventricles are still in
full relaxation
Ventricular depolarization complete →Ventricular contraction is in progress
Start of ventricular repolarization (T wave) → Ventricular contraction is
still in progress
No electrical or mechanical activity at completion of cardiac cycle.
2 main events for a complete cardiac cycle
1st event of the cardiac cycle
Ventricular systole (contraction) - With 2 periods:
1) Isovolumic ventricular contraction (i.e., Steady and rapid increase in
ventricular pressure, no change in ventricular volume and all the
valves are closed). It begins with ventricular contraction, coincides
with the peak of the R-wave of the ECG Between the closure of
atrioventricular (AV) valves (i.e. When ventricular pressure exceeds
atrial pressure) and the opening of the semilunar valves (i.e., when
ventricular pressure exceeds aortic pressure). Blood volume in the
ventricle during this period is known as end-diastolic volume (EDV).
Increase in the atrial pressure is observed caused by the closure of AV
valve. 1st low-pitched heart sound can be heard in this period often
being described as "lub" sound caused by the closure of AV valves.
2) Ventricular ejection- Begins with the opening of the semilunar valves
(AV valves are now closed). Further sub-divided into 2 phases:
i)
Rapid ejection phase- Starts with the initial opening of the
semilunar valves. Sharp increase in the ventricular and aortic
ii)
pressure but with ventricular pressure slightly above the aortic
pressure. There is a sharp decrease in ventricular volume. The
sudden drop in atrial pressure is caused by the descent of the base
of the heart and the stretch of the atria during ventricular
contraction. Ends when: left ventricular pressure is at its peak @
this particular cardiac cycle and ventricular pressure = aortic
pressure. It is approximately 1/3 of the whole ejection phase in
duration.
Reduced ejection phase- Both the ventricular and aortic pressures
are starting to decrease. Continuation of blood flow from ventricle
to aorta with ventricular pressure slightly less than aortic
pressure. Decline in aortic pressure is due to the runoff of blood
from aorta to the systemic circulation. This phase coincides with
the onset of T-wave of the ECG. This period occupies approximately
2/3 of the whole ejection period in duration.
Second main event
Ventricular diastole (relaxation) With 2 periods:
1) Isovolumic ventricular relaxation- No change in ventricular volume
during this period while the ventricle is relaxing but with a steady
decrease in ventricular pressure. semilunar and AV valves are closed.
Period between closure of semilunar valves and opening of the AV
valves. There is a sudden increase in aortic pressure (dicrotic notch)
due to the closure of aortic valve. Onset of second heart sound with a
higher pitched sound described as a "dub" sound associated with the
closure of semilunar valves. Volume of blood in the ventricle during
this period is known as end-systolic volume (ESV). Stroke volume (SV)
as the amount of blood ejected by the heart per beat( SV = EDV – ESV).
2) Ventricular filling (2nd period) Sub-divided into 2 phases:
i)
Rapid filling phase- Majority of ventricular filling occurs in this
phase (~ 70%) By passive filling (no atrial contraction). 3rd heart
sound (very faint) can be heard associated with the turbulent blood
flow during the ventricular filling. The initial drop in atrial
pressure is due to the opening of the AV valve.
ii)
Reduced filling phase- Atrial contraction occurs in this phase Which
coincides with: a) The mid-way of P-wave of the EC, b) A sudden
increase in the atrial pressure, c) An additional increase in
ventricular volume (~ 30%). This phase also known as the active
ventricular filling phase. This phase ends with the closure of the
AV-valve (The beginning of the isovolumic ventricular contraction).
Class 9: Cardiovascular system
1) Know the functions of the cardiovascular system
CV system is essential for most of the multicellular organisms
CV function primarily as a transport system
→ Facilitates exchange e.g.) nutrients, gases, metabolites, and heat
→ Enhances communication e.g.) signal molecules such as hormones
→ Establishes defense (inflammatory response, antibody-antigen
interaction, hemostasis)
Final mechanism for transport is the same as in unicellular organisms
2) Know the various components of the cardiovascular system
3 basic components in human CV system:
➢ Muscular pump (heart)- The heart is on the ventral side of the thoracic
cavity, tilted to the right and in between the lungs. Cardiac tamponade is
Buildup of pericardial fluid within the pericardial sac causes a decrease in
cardiac output. There are fibrous dense connective tissue rings separating
atria from ventricles. There are 4 rings that surround the valves of the
heart, forming the structural foundation of the heart valves. They fuse with
one another and merge with the inter- ventricular septum. Fibrous rings
(skeleton) function as an electrical insulator, preventing the propagation of
electrical impulse from atria to ventricles through contractile myocytes. The
muscular pump has 5 sub-systems
i)
Pacemaker & conducting systems- 2 basic sets of intrinsic
pacemaker tissues in heart SA & node AV node. An “ectopic focus”
is→ any part of the heart other than the SA node that generates a
heartbeat. AV has Lowest conduction velocity to: ensure adequate
ventricular filling & Limits the frequency of ventricular activation.
Purkinje fibers has Highest conduction velocity for: Fast &
coordinated ventricular contraction
ii)
Heart muscle (myocardium)- With various wall thicknesses
(proportional to the pressure generated). With 2 important
features: 1) Intercalated disk→ Forms tightly coupled structure
with neighboring cells, 2) Gap junction→ Forms electrical synapse
with low resistance.
iii) Heart valves- with 4 sets of valve: Aortic valve (semilunar),
Pulmonary valve (semilunar), Bicuspid valve (mitral), Tricuspid
valve. Prolapse→ Condition that the chordae tendineae fail and
valve is pushed back into the atrium during ventricular
contraction, giving rise to ventricular regurgitation.
iv)
Coronary circulation- Receives roughly 5% of the resting cardiac
output. Most of the blood returns into the right atrium via coronary
sinus. Blood enters the coronary arteries through the two coronary
orifices located at the root of the aorta behind the right and left
cusps of the aortic valves. The right coronary artery originates
from the right coronary orifice (sinus of Valsalva). The left
coronary artery originates from the left coronary orifice and after a
short course, bifurcates into the anterior interventricular artery,
also known as left anterior descending artery (LAD), and
circumflex artery. The main stem of the left coronary artery arises
from the left coronary aortic sinus. It divides into the circumflex
and anterior interventricular branches.
v)
Autonomic innervation- Parasympathetic→-ve chronotropic (rate)
Sympathetic→+ve chronotropic & inotropic (force). ANS modulates
rather than initiates cardiac functions.
➢ Distribution networks (blood vessels)- With 3 divisions
1) Systemic circulation containing aorta, arteries, and arterioles 2)
Capillaries 3) Venous circulation including venules, veins, and vena cava.
Majority of the organs are in a parallel arrangement with 3 major portal
systems: 1) Blood enters into the digestive tract and later re-enters the
liver, 2) In kidney’s filtration systems, 3) Hypothalamic-hypophyseal
(pituitary) portal system. Parallel arrangement of the circulatory systems
is to ensure: 1) Adequate distribution of oxygenated blood into all the
organs, 2) Each organ will receive the same oxygenated arterial blood with
approximately the same perfusion pressure. Arteries are known as
resistance vessels. Veins are known as capacitance vessels. Capillaries are
the sites for exchange. One of the most important functions of the blood
vessels is for volume & pressure regulation.
Transport medium (blood)- Total volume ≈ 5 - 6 liters. Plasma ≈ 3 liters
(55% of total blood volume); Electrolytes→ rich in Na+ & Cl- ,Plasma
protein, carbohydrates, & lipid. Erythrocytes (red blood cells) ≈ 45%. Buffy
coat → leukocytes (white blood cells) and thrombocytes (platelets).
3) Know the ionic basis for the autorhythmicity of the heart
Autorhythmicity= combination of both the automaticity (ability of a cell to
initiate its own pacemaking activity) and rhythmicity (ability of a cell to
maintain the regularity of pacemaking activity) properties (both properties
are intrinsic to cardiac pacemaker cells)
Ionic basis Automaticity:
Membrane slowly depolarizes and drifts toward threshold between action
potentials. Pacemaker cells exhibit the slow response in their action
potentials (AP with a sluggish rising phase- phase 0). 3 phases of the
permeability changes for various ions are observed in the AP of the
pacemaker cells
Phase 4: spontaneous gradual depolarization is largely due to the slow ionic
influx creating the pacemakers current If (If is caused by the slow leak of
Na+ into the pacemaker cells through Na+ channels which open during
repolarization). Also, with rapid decays of K+ efflux due to the closing of
voltage-gated K+ channels. Opening of transient Ca2+ channels during last
half of the pacemaker potential that give rise to the Ca2+ influx. The net
result is the resting membrane potential becomes progressively more
positive for the pacemaker cells.
Phase 0: opening of the long-lasting voltage-gated channels for Ca2+ (after
reaching threshold about -55mV). Depolarization occurs once the threshold
potential is reached. No fast Na+ channels is involved
Phase 3: starts with the gradual closing of the voltage gated Ca2+ channels
voltage -gated K+ channels now activated. Repolarization occurs. Once the
membrane potential reaches max diastolic potential, phase 4 will start
again
Ionic basis of Rhythmicity:
Three variables that can influence cardiac rhythmicity (heart rate)& related
to the time required for the membrane potential of pacemaker cell to reach
its threshold
1) Rate of diastolic depolarization (at phase 4 -case “b” to “a”). NE
(norepinephrine) increase rate of diastolic depolarization
2) Maximum diastolic potential (MDP) (case “b” to “c”). Induces
hyperpolarization by increase K+ efflux & decreased Ca++ influx. Ach
also decreases the slope of phase 4
3) Threshold potential (TP) (case “a” to “b”) ex. Quinidine . An
antimalarial and antipyretic (decreased fever) drug - it shifts the
threshold voltage towards 0 i.e.) Takes longer time to reach the TP,
decreased HR.
Class 10: Cardiovascular system
1) Know the dynamics of various factors that can influence cardiac output
CO = HR X SV. SV = f(preload; afterload; & myocardial contractility). During
exercise, HR can be increased by over 100% whereas stroke volume can
only be increased by ~50%. changes in HR alone can cause an inverse effect
on SV. Ventricular filling time decreases as the diastolic period decreases
due to the increase in HR.
Increase in CO during exercise is due to 3 factors (beside HR):
1) Positive inotropic effect to the contractile myocytes primarily caused
by the increase of sympathetic activity during exercise. NE & Epi are
potent β1 agonist (increase force of ventricular contraction); Increase
in force of contraction will lead to an increase in SV and therefore CO.
2) Reduction in peripheral vascular resistance- Exercise produces
vasoconstriction to all the vessels, including the contracting muscles
due to β1 activation (gives rise to transient ischemia). NE & Epi are
potent α agonist (vasoconstriction); Vasoconstriction is followed by
vasodilatation. By vasodilators such as adenosine (as metabolic byproducts) generated during transient ischemia; Process known as
metabolic autoregulatory phenomena (reduction in vascular
resistance within the contracting tissues). Metabolic autoregulatory
phenomena leads to an increase in blood perfusion to the working
tissues.
3) Compressing action of the contracting skeletal muscles (skeletal
muscle pump) together with the venous valves to enhance the venous
return. When the skeletal muscles compress the veins, they force
blood toward the heart (the skeletal muscle pump).
There are three primary physiological parameters that can influence SV:
Preload: is affected by the degree of stretching of the cardiac myocytes and
is related to the ventricular volume at the end of diastole (just before the
onset of the ventricle contraction). Same as the left ventricle end-diastolic
ventricular (blood) volume (LVEDV). Indirectly related to left ventricular
end diastolic pressure (LVEDP) for a given heart. Increases in preload alone
will increase SV. Normally preload is determined by:
Ventricular compliance (compliance is defined as the change in volume
divided by the change in pressure)
ΔV / ΔP = compliance Or ΔP / ΔV = stiffness
Venous Return: stretches the myocytes, increases force of contraction,
higher SV (frank-starling mechanism or starling’s law)- to ensure the
outputs of both ventricles are matched over time and to prevent the shifting
of blood between pulmonary and systemic circulations
Length-tension relationship: biophysical basis for the starling’s law of the
heart.
When cardiac myocytes are stimulated with an increase in preload- active
tension of the heart is increased & increase in active tension will lead to an
increase in force of contraction of the heart. Increase in force of contraction
leads to an increase in SV (but with no change in ESV). ESV is the volume of
blood left in the ventricle after the closure of the aortic valve.
Afterload: (wall stress)
σ = wall stress, p = intra-ventricular pressure, r = ventricular radius, h =
ventricular wall thickness From the Laplace’s law:
σ α (p • r) / 2h
I) i)σ increases in response to a higher pressure load (p) e.g.) Hypertension
↓ SV
ii) σ increases in response to an increase in the ventricular chamber size (r)
e.g.) an ↑ in pre-load → ↑ SV, but with ↑ work load.
iii)Increases in wall thickness will reduce wall stress (σ) and reduce the
afterload e.g.) Left ventricular hypertrophy→ same SV with ↓ work load
Contractility: (inotropic state of the heart)
Defined as the property of the contractile myocytes that account for the
strength of contraction. Related to intrinsic cellular mechanisms that
regulate the interaction between actin and myosin. Independent of the
preload and afterload. A true indicator of inotropic state normally
influenced by chemical or hormone on the cardiac muscles. Increases in
contractility will increase SV
2) Know the forces that can affect the capillary fluid exchange
Capillary blood pressure (BP)- Same as hydrostatic pressure. Forces fluid
out of the capillaries into the interstitial fluid
Interstitial fluid hydrostatic pressure (IFP)- Pressure created by the
interstitial fluid. Forces fluid back to the capillaries. Usually negative
because of lymphatic vessels constantly drains excess fluid from the tissue
spaces back to the blood stream, creating suction effect.
Plasma-colloid or Blood-colloid osmotic pressure (BCOP)- Also known as
oncotic pressure. Caused by plasma proteins. Encourage fluid move back
into the capillaries because plasma has a higher protein concentration.
Interstitial colloid osmotic pressure (ICOP)- Created by the plasma proteins
that leak across the capillary wall into the interstitial space. These proteins
will return back to the blood stream through the lymphatic system.
Encourage fluid move out of the capillaries.
Net filtration pressure (NFP) is responsible for moving fluid across capillary
bed
At the arteriole side of the capillary: NFP (arteriole) = (netHP) – (netOP)
Forces influence capillary fluid exchange at the venule side of the capillary
With a drop in BP: 35mmHg at the arteriole, 16mmHg at the venule
Usually less than 1% of fluid filtered out of the capillary, coupled with
lymphatic return, interstitial fluid pressure remains relatively constant
- At the venule of the capillary:
- Along the capillary bed, only protein free plasma escapes into the
interstitial space by filtration
- With less than 1% of fluid filtered out of the capillary
- Plasma protein concentration between arteriole and venule are
relatively constant
- With protein free fluid being reabsorbed back to the capillary at the
distal end
- Interstitial colloid osmotic pressure (ICOP) appears to increase alone
the capillary bed
- Most of the fluid that force out from the arteriole will re-enter back to
the venule
Edema- Edema is the accumulation of fluid in the interstitial space. It can be
caused by:
→ Increase permeability of capillary e.g.) Increase histamine release
→ Decrease plasma protein e.g.) Severe liver damage Protein, starvation,
kidney problem
→Elevation of venous pressure e.g.) Venous thrombosis
→ Blockage of lymphatic system
Class 11: cardiovascular system
Class 13: Respiratory system
1) Describe the anatomy structure and function of the respiratory system
components Nose, Pharynx, Larynx, Trachea, Bronchi, Lungs
Structure
Upper respiratory system
Nose, nasal cavity, & pharynx
Lower respiratory system
Larynx, trachea, bronchi, & lungs
Function
Conducting zone
Nose to terminal bronchioles
Respiratory zone
Respiratory bronchioles to pulmonary alveoli