I. Circulatory System Notes
1. Major Blood vessels
Label the following blood vessels on the diagram below: subclavian arteries and veins,
jugular veins, carotid arteries, mesenteric arteries, anterior and posterior vena cava,
pulmonary veins and arteries, hepatic vein, hepatic portal vein, renal arteries and veins,
iliac arteries and veins, coronary arteries
and veins, aorta
2. Route of Blood Through the Heart and Lungs
-deoxygenated blood returning to the heart from the body enters the right atrium
(auricle) of the heart through 2 large veins. The Posterior (inferior) vena cava (brings
blood back from the body) and the Anterior (superior) vena cava (brings blood back
from the head).
-this blood first travels to the right ventricle through an atrioventricular valve (A-V valve)
and is then sent to the lungs to be reoxygenated. It first travels through a semilunar
valve which separates the right ventricle and the pulmonary artery. The circulation of
blood between the lungs and heart is called the pulmonary circuit.
-oxygenated blood returning from the lungs enters the left atrium of the heart through
the pulmonary vein, travels through another A-V valve into the left ventricle and leaves
the heart to enter the body through another semilunar valve which separates the left
ventricle and the aorta. The Chordae Tendinae prevent the valves from inverting
(turning inside out) when they shut. The blood will now circulate through the body and
back into the heart again through the vena cavas. This circulation of blood through the
body to meet the needs of the tissues is called the systemic circuit.
Be able to label the chambers, blood vessels, septa, chordae tendinae, and valves in
the 2 diagrams of the heart below
W = posterior vena cava X = anterior vena cava
Y = Aorta Z = pulmonary artery
3. Control of the Heartbeat
-the heart is controlled by a pacemaker called the Sino-atrial node (S-A node) .(it is
found in wall of the right atrium where the vena cavas enter.) It sends a nerve impulse
that causes the atria to contract. The impulse is carried to the atrioventricular node (A-V
node) (located in the base of the right atrium.) The A-V node delays the ventricle beat
until the atrial beat is complete and then sends the impulse to the purkinje fibers which
cause the ventricles to contract. In this way the atria beat finishes before the ventricle
beat begins. When the heart is in a relaxed state it is called diastole and in a contracted
state it is called systole.
4. Factors Which Regulated Blood Pressure
i. Arteries and veins - Since the arteries are closer to the heart, blood pressure is
higher in the arteries than in the veins. The elastic structure of the arteries and the
subsequent expansion and contraction contribute to increased blood pressure.
ii. ADH - This hormone is released from the posterior pituitary when the osmotic
pressure (amount of solute or salt is high. The blood is concentrated...) of the body
fluids or blood is high. This causes the collecting duct and distal tubule of the kidney to
reabsorb water increasing the volume of body fluids to dilute the blood, therefore
increasing blood pressure.
iii. Angiotensin - The juxtaglomerular apparatus senses a drop in blood pressure and
releases rennin. Rennin catalyzes the conversion of Angiotensinogen to Angiotensin.
Angiotensin stimulates the release of Aldosterone from the Adrenal Cortex which
causes the kidney to reabsorb sodium into the blood. The reabsorption of sodium
increases the osmotic pressure of the blood (makes the blood more concentrated) and
causes water to move by osmosis back into the blood from the body tissues. ADH is
also secreted which causes further reabsorption of water. Reabsorption of water
increases the blood volume, which increases blood pressure.
iv. Carotid arteries and stretch receptors l - increased blood pressure will cause the
pressure receptors in the carotids to send a signal to the medulla of the brain. The
medulla will either, slow the heart rate down, which decreases the amount of blood
pumped into the system, which reduces the volume of fluid, causing a reduction in blood
pressure, or it will cause the blood vessels to dilate (get bigger in diameter) also
reducing the pressure.
v. Nervous system i. Sympathetic system (adrenalin) will increase heart rate, which increases amount of
blood pumped and increases pressure. It also constricts the lumen (size of the
diameter) of the arteries increasing blood pressure.
ii. Parasympathetic system (acetylcholine) will decrease the heart rate and amount of
blood pumped reducing the pressure. It also dilates the lumen of the arteries decreasing
blood pressure
5. Nervous Control of the Heart
i. Sympathetic system - increases the rate and strength of the heart beat and
constricts the lumen of the arteries increasing blood pressure.
ii. Parasympathetic system - decreases the rate and weakens the strength of the
heart beat and dilates the lumen of the arteries decreasing blood pressure
6. Structure of the Blood vessels
i. Arteries - are blood vessels that carry blood away from the heart. They are composed
of three layers. (1) an outer layer of connective tissue, containing elastic fibers which
give the arteries their characteristic elasticity; (2) a middle layer of smooth muscle which
can regulate the size of the arterial lumen (opening); and (3) an inner layer of
connective tissue lined with endothelial cells. Arterioles are smaller versions of arteries
ii. Veins - are blood vessels that carry blood towards the heart. The walls of veins are
thinner and the lumens larger than those of arteries. The same three layers are present
but the outer layer has fewer elastic fibers and the middle layer of smooth muscle is
much thinner. The walls of the veins are therefore much less rigid and easily change
shape when the muscles press against them. Veins also have valves which prevent
backflow and maintain the direction of blood flow to the heart. Venules are smaller
versions of veins. Look a the diagram of a vein shown below. Notice the valve. Blood
flows in the direction the valve is pointing.
iii. Capillaries - are blood vessels that connect the arteries and veins. (1) They are thin
walled, (one endothelial cell layer thick) which permits rapid diffusion of substances
through the capillary membrane. (2)They are extensively branched, which increases the
cross sectional area of the capillary system, which causes the blood to slow down
allowing more time for the exchange process to occur. (3) They have a very small
diameter which provides friction which increases the resistance of flow. This causes the
blood pressure to drop in the capillaries which allows easier passage of materials
between the tissues and the blood.
7. Fetal and Adult Circulation
Since the fetal lungs do not function to exchange gases, and oxygentated blood is
obtained from the mother, there are some significant differences in the circulatory
system of adults and the fetus. The following structures (In order from the mother to the
fetus) are present in the fetus but not in the adult:
i. The venous duct - This structure connects the umbilical veins, that lead from the
placenta, with the vena cava of the fetus. Oxygen diffuses across the placenta into the
blood of the umbilical veins, the blood then travels through the venous duct, into the
vena cava, and mixes with the fetus' deoxygentated blood.
ii. The oval opening - it is an opening between the right and left atria, that allows blood
from both sides of the heart to mix. Normally deoxgenated blood enters the right atrium
via the anterior or posterior vena cava but since the fetus receives oxygentated blood
from the mother, the right atrium contains mixed blood. There is no need for the blood to
go to the lungs to be oxygenated therefore the oval opening allows blood to enter the
pulmonary circulation directly.
iii. The arterial duct - Blood leaving the right ventricle normally goes through the the
pulmonary artery to the lungs.The arterial duct is a connection between the pulmonary
artery and the aorta so blood can bypass the non-functioning fetal lungs.
iv. The Umbilical arteries and veins - These vessels carry wastes and oxygen to and
from the placenta. The arteries carry wastes and CO2 to the placenta the veins carry
oxygen from the placenta
Identify the parts listed above in the diagram of the fetus below
II. Blood and Lymph system
1. Major components of blood -made up of the following things:
a. Plasma - Blood cells are suspended in the plasma. Plasma makes up 55% of the
blood. Made up mostly of water (90%) it carries a number of important things like:
i. Fibrinogen - plasma proteins made in the liver involved in blood clotting
ii. Gammaglobulins - plasma proteins made in the liver involved in fighting infections
(immunoglobulins = antibodies)
iii. Albumin -plasma proteins that maintain the high osmotic potential of the plasma
preventing loss of fluid from the bloodstream to the tissues
iv. Angiotensinogen - Involved in reabsorption of sodium and control of blood volume
and blood pressure
v. Nutrients -(glucose, fats and amino acids)
vi. Gases - oxygen and carbon dioxide
vii. Miscellaneous substances - various ions, hormones, and waste materials (eg.
urea and ammonia.)
b.) Blood cells - make up 45% of the blood and consists of the following:
i. Red blood cells - Red blood cells, also called erythrocytes, transport oxygen. They
are biconcave, (See diagram in text), live for 120 days and are produced in the red bone
marrow of adults at the rate of about 1.5 million per second. As the blood cells mature
they extrude their entire cell contents. (all the cell organelles) and use the increased
area to carry hemoglobin. (hemoglobin carries oxygen in red blood cells).
A diagram and an electron micrograph of red blood cells
ii. White blood cells - white blood cells defend the body against viruses, bacteria, and
other foreign invaders. They do this by engulfing invaders or by producing antibodies.
There are 6000 to 9000 white blood cells per cc. of blood. Notice that the white blood
cells in the diagram have nuclei
There are two different kinds of white cells:
Neutrophils - make up 60-70% of the white cells, produced in the red bone marrow,
arrive at the site of an injury, first, are very active in phagocytosis and play a role in
wound healing.
Lymphocytes - two kinds of lymphocytes. B cells are produced in the lymph nodes and
are involve in antibody synthesis. T cells originate in the thymus and are involved in
rejection of foreign tissue (organ transplants) and other immune responses.
iii. Platelets - look like plates, are colorless, round or biconcave, are smaller than red
blood cells, play important roles in blood clotting and are produced in the bone marrow.
2. Lymph system - Fluid is forced out of the capillaries by blood pressure. Some of the
fluid is returned to the capillaries by osmosis the rest is collected and returned by the
lymph system. This system is similar to the venous system (the vessels are thin walled
and have valves) except the vessels end blindly in the tissues. Right lymphatic duct
empties into the right subclavian vein and the thoracic duct empties into the left
subclavian vein. Lacteals are blind ends of lymph vessels. As the lymph system
circulates it passes through lymph nodes. These nodes are found in clusters in the
groin, armpits, and neck. They have 2 functions; they manufacture B cells, and remove
foreign particles from the lymph. The lymph nodes also contain leukocytes to attack
bacteria and foreign invaders.
b. Organs of the lymph system i. Spleen - manufactures lymphocytes, takes out defective or damaged red blood cells,
removes iron from the hemoglobin and recycles it to the bone marrow.
ii.Thymus - produces T cell type lymphocytes.
3. Capillary Fluid Exchange- Exchange of materials at the tissue capillaries
a. Arteriole side of capillary bed - blood pressure higher than osmotic pressure
-blood from arterioles enters capillary beds of various tissues. The blood is carrying
oxygen (on the hemoglobin of Red Blood Cells) and nutrients like amino acids and
glucose in the plasma.
-on the arteriole side of the capillary bed the blood pressure is higher than the osmotic
pressure.
-the higher blood pressure pushes fluid containing oxygen, water and nutrients (amino
acids and glucose) into the tissues.
-as the blood flows into the capillary bed it slows down. This provides time for the fluid
containing oxygen and nutrients to be pushed out of the capillaries by blood pressure
and for the nutrients and oxygen to diffuse into the tissue cells.
-Large molecules like red blood cells and plasma proteins, cannot cross into the tissues.
This fluid in the tissues or tissue fluid has all the components of plasma except for
proteins.
b. Midsection of capillary bed - diffusion of material into the cells
-Materials move into the cell by diffusion eg: high concentrations in tissue fluid move to
low concentrations in the cell and vice versa. For example:
- Oxygen diffuses into the cell from the tissue fluid, cell respiration uses the oxygen and
produces carbon dioxide and water which diffuse out of the tissues, into the tissue fluid
and eventually into the capillary bed.
- Amino acids diffuse into the cell and are broken down producing amino groups. These
amino groups are converted into ammonia which also diffuses out of the cell, into the
tissue fluid and then into a capillary bed.
c. Venule side of capillary bed - blood pressure lower than osmotic pressure
-blood pressure is much reduce and is lower than osmotic pressure. As a result osmotic
pressure (The force that causes the flow from a high concentration to a low
concentration) fluid is forced back into the capillary.
-this bring additional amounts of waste materials (carbon dioxide and ammonia)
Circulatory System Quiz Questions
1. What is the name of the heart chamber that:
a. receives blood returning from the body
b. receives blood returning from the lungs
c. pumps blood to the body
d. pumps blood to the lungs
3. What is the name of the blood vessel that carries blood from the:
a. body to the Right atrium
b. head to the Right atrium
c. Right Ventricle to
the lungs
d. Left Ventricle to the body e. lungs to the Left atrium
f. intestines to
Inferior Vena Cava
g. aorta to the kidneys
h. kidneys to Posterior Vena Cava i. aorta to the arms
j. aorta to the head
k. arms to the Anterior Vena Cava l. head to Anterio
Vena Cava
m. intestines to liver
n. liver to Inferior Vena Cava
o. from aorta to
legs
p. aorta to heart muscle
q. legs to posterior Vena Cava
r. heart muscle
back to heart
s. aorta to the intestines
4. What is the definition of: a. systole?
b. diastole?
5. What is the name of the valve between the atria and ventricles
6. What is the name of the valve between the heart chambers and blood vessels
7. What is the definition of a. systemic circulatory system
b. pulmonary
circulatory system
8. What is the definition of
a. artery
b. vein
c. arteriole
d.
venule
e. capillary
9. Name any 4 structures that found in the circulatory system of a fetus but not in the
adult and describe their function.
10. What is the name of the vessels that provide oxygen to heart tissue
11. What is the name of the vessels that carry blood intestines to the liver
12. Be able to identify the parts of the heart from a diagram
13. What is the name of the tissue that lines the inside of a blood vessel
14. The general name for vessels that carry blood away heart
15. What chemical causes blood vessels to constrict
16. What is the name of the structure that divides into the right and left pulmonary
arteries
17. What is the function of the Chordae tendinae
18. What structure controls the beating of the a. atria b. ventricles
19. What is the function of the Purkinje fibers
III. Blood Quiz Questions
1. What is the function of platelets
2. What is the function of neutrophils
3. What is the function of red blood cells (RBC)
4. Name two kinds of lymphocytes and their functions
5. Name the 3 kinds of plasma proteins and their functions
6. What is another name for red blood cell
7. Where are red blood cells produced
8. Name two locations where are lymphocytes produced
9. Where are neutrophils produced
10. What is the function of lymph nodes
11. Where are red blood cells produced
12. Name the function and the shape of the following blood cells: a. red blood cells. b.
lymphocytes c. neutrophils d. eosinophils e. basophils f. monocytes
13. Name two organs of the lymph system and their functions
14. What is the definition of antigens and antibodies.
15. What does an antibody do to an antigen
16. Name 3 components of plasma and describe their functions
17. Name the substances which make up blood
18. What shape do platelets have
IV. Circulatory System Subjective Questions
1. A person receives a severe cut in a traffic accident and is losing blood quickly.
Outline all the things that would occur in the body to compensate for the the drop in
blood presssure.
2. Name any two factors which regulate blood pressure and describe how they function
to accomplish this.
3. Explain how the following would respond to an decrease in blood pressure.
a. The autonomic nervous system
b. Aldosterone concentration in the blood
c. Antidiuretic hormone (ADH)
4. Outline the role each of the following plays in maintaining the heartbeat:
a.) the sinoatrial node
b.) the atrioventricular node
5. List 3 functions of the lymph system
6. Describe the difference between hypertension and hypotension
7. Starting at the vena cava and ending at the aorta, name all the structures, vessels
and heart chambers, in order, that deoxygenated blood would contact as it travels
through the heart on its way to be reoxygenated, and once it has been oxygenated, the
path through the heart again on its way back into the body.
(1 mark for order, 1/2 mark per structure, 6 marks total)
VENA CAVA, __________, __________, __________, __________, __________,
LUNGS
__________, __________, __________, __________, __________, AORTA
8. Explain how each of the following makes the fetal circulatory system different from
the adult circulatory system.
a.) oval opening
b.) venous duct
c.) arterial duct
d.) umbilical arteries and veins
9. Choose any two structures found in the fetal circulation but not in the adult circulation
and explain the functions of these structures.
10. List 2 functions of lymph nodes
11. Relate the structure of arteries and veins to their functions:
a. Arteries
b. Veins
12. List any two characteristics of the:
a. pulmonary system
b. systemic system
V. BLOOD SUBJECTIVE QUESTIONS
1. Relate the components of blood to their functions
2. What structure filters out foreign particles in the lymph
3. Describe capillary-tissue fluid exchange
4. Describe the conditions that facilitate the exchange of materials between the capillaries and
the tissues