Chapter 15
Cardiovascular System + Respiratory System
Objectives:
1. Describe the functions of the circulatory system
2. List the components of the circulatory system
3. Describe the structure and function of the heart
4. Describe the control of heart contractions
5. Trace the path of cardiopulmonary circulation
6. Name and describe the specialized circulatory systems
7. List the types of blood vessels
8. Identify the principal artery and veins
9. Trace the path of cardiopulmonary circulation
Respiratory System
1. Describe functions of respiratory system
2. Describe the structures of the organs of respiration
3. Explain respiratory process
4. Describe what is happening on the molecular level
Circulatory System
1. Circulatory system is the longest system in the body
a. If you were to lay all of the blood vessels on end to end, then it would stretch
out 60,000 miles
2. Functions of the Circulatory system
a. Heart is the pump that circulates blood to all parts of the body
b. Arteries, veins, and capillaries are the structures that take blood from the
heart to the cells and return blood from the cells back to the heart
c. Blood carries oxygen and nutrients to the cells and carries the waste products
away
d. The lymph system returns excess fluid from the tissues to the general
circulation
Organs of the Circulatory System
3. The organs of the circulatory system include:
a. Heart
b. Arteries
c. Veins
d. Capillaries
e. The blood and parts of the lymphatic system are also part of the system
Major Blood Circuits
4. Blood leaves the heart through arteries and returns by veins.
5. The blood uses two circulation
routes:
a. The general (or systemic)
circulation carries blood
throughout the body
b. The cardiopulmonary
circulation carries blood from
the heart to the lungs and
back
The Heart
6. The blood’s circulatory system is
extremely efficient
7. The main organ responsible for this efficiency is the heart
a. Human heart about the size of a closed fist
b. 12-13 oz.
8. Vital to life: if heart stops beating, life stops
a. Ex.// If the blood flow to the brain ceases for 5 seconds or more, the subject
loses consciousness. After 15 to 20 seconds, the muscles twitch convulsively;
after 4 to 5 minutes without blood flow, the brain cells are irreversibly
damaged.
9. Located in the thoracic cavity between the lungs, behind sternum, but in front of the
thoracic vertebrae
a. Although closely located to the midline, the heart’s apex (conical tip) lies on
the diaphragm and points to the left of the body
b. It is at the apex where the heartbeat is
the most easily felt and heard through
the stethoscope
Structure of the Heart
10.
The heart is a hollow, muscular, double
pump that circulated the blood through the
blood vessels to all parts of the body
a. Surrounding the heart is a double-layer of fibrous tissue called the
pericardium
1. Between these two layers is a lubricating fluid called pericardial fluid
1. This fluid prevents the two layers from rubbing against each other
and creating friction
b. Cardiac muscle tissue, or the myocardium, makes up the major portion of the
heat
c. The inner lining lies a smooth tissue called the endocardium
1. The endocardium covers the heart valves and lines the blood vessels,
providing smooth transit for the flowing blood
d. A frontal view of the human heart reveals a thick, muscular wall separating it
into a right half and a left half.
1. This separation known as the septum, completely separates the blood
in the right half from that in the left half
2. Structures leading to and from the heart are:
1. Superior vena cava
and inferior vena cava
a. Large veinous
blood vessels
which bring
deoxygenated to
the right atrium
from all parts of
the body
2. Coronary sinus
a. From the heart
muscle to the
right atrium
3. Pulmonary artery
a. Takes blood away from the right ventricle to the lungs for
oxygen
4. Pulmonary veins
a. Bring oxygenated blood from the lungs to the left atrium
5. Aorta
a. Takes blood away from the left ventricle to the rest of the
body
11.
Chambers and Valves
a. The human heart is separated into right and left halves by the septum
1. Then, there are two lower parts and two upper parts
1. The upper parts are the atriums (auricles)
2. The lower parts are the ventricles
2. The heart has four valves which permit the blood to flow in one
direction only
1. These open and close during contraction of the heart, preventing
the blood from flowing backwards
2. Atrioventricular valves are located between the atria and
ventricles
a. Tricuspid valve
i. Is positioned between the right atrium and the right
ventricle
ii. Its name comes from the fact that there are three
points, or cusps, of attachment
iii. The chordae tendinae are small fibrous strands
connecting the edges of the tricuspid valve to the
papillary muscle that are projections of the
myocardium
iv. When the right ventricle contracts, the papillary
muscle contracts, pulling the chordae tendinae
preventing inversion of the tricuspid valve
b. Bicuspid or mitral valve
i. Located between the left atrium and left ventricle
ii. Blood flows from the left atrium into the left ventricle,
the mitral valve prevents backflow from the left
ventricle to the left atrium
3. Semilunar valves are located where blood will leave the heart
a. Pulmonary semilunar valve
i. Is found at the opening of the pulmonary artery
ii. It allows blood to travel from the right ventricle into
the pulmonary artery and then into the lungs
(deoxygenated blood)
b. Aortic semilunar valve
i. Is at the opening of the aorta
ii. This valve permits the blood to pass from the left
ventricle into the aorta, but not backwards
(oxygenated blood)
Physiology of the Heart
12.
The structure of the heart allows it to function as a double pump, with two
major sides:
a. Right heart
1. Deoxygenated blood flow
b. Left Heart
1. Oxygenated blood flood
c. Path of deoxygenated/ oxygenated blood flow through the heart
1. Blood reaches heart through
superior vena cava and inferior
vena cava
2. To right atrium
3. To tricuspid valve
4. To right ventricle
5. To pulmonary valve
6. To main pulmonary artery
7. To left pulmonary artery and
right pulmonary artery
8. To lungs- blood receives oxygen
9. From lungs to pulmonary veins
10.
To left atrium
11.
To mitral (bicuspid valve)
to left ventricle
12.
To aortic valve
13.
To aorta (largest artery in the body)
14.
Blood with oxygen then goes to all cells of the body
15. http://www.sumanasinc.com/webcontent/animations/conten
t/human_heart.html
Conduction System of Heart Contractions
13.
A heart removed from the body will continue to beat
rhythmically for a while, which shows that heartbeat generates
within the heart itself. Heart rate is also affected by the endocrine and nervous
systems. They myocardium contracts rhythmically to perform its duty as a forceful
pump
a. Control of heart muscle contraction is found within a group of conducting cells
located at the opening of the superior vena cava into the right atrium.
1. These cells are known as the sinoatrial (SA) node, or pacemaker
1. The SA node sends out an electrical impulse that begins and
regulates the heart. The impulse spreads out over the atria,
making them contract
2. This electrical impulse eventually reaches the atrioventricular (AV)
node, which is another conducting cell group located between the atria
and ventricle
3. This impulse then reaches other conducting fibers that complete heart
contraction (beat)
Blood Vessels
1. The heart pumps the blood to all parts of the body through a remarkable system of
three types of blood vessels: arteries, capillaries, and veins.
a. Arteries
i. Carry oxygenated blood away from the heart to the capillaries
1. Exception- pulmonary arteries carry deoxygenated blood
ii. Transport blood under very high pressure
iii. They are elastic, muscular, and thick-walled
1. Makes them the strongest of three vessel types
iv. Arterial walls consist of three different layers
1. Tunica adventitia (externa)
a. Outer layer
b. Consists of fibrous
connective tissue and
smooth muscle
c. Allows arteries to
withstand sudden large
increases in internal
pressure
2. Tunica media
a. Middle layer
b. Muscle cells arranged
in circular pattern
c. Controls the artery’s diameter by dilation and constriction
i. Reduces hearts work
3. Tunica intima
a. Inner layer
b. Consists of three other layers
c. Gives vessels smooth lining, which allows for the free flow
of blood
b. Capillaries
i. Smallest blood vessels
ii. Connect the arterioles with venules (very tiny arteries and veins)
iii. Capillary walls are extremely thin to allow for the selective permeability
of various cells and substances
1. Nutrient molecules and oxygen pass out of the capillaries and into
the surrounding cells and tissues
2. Metabolic wastes such as carbon dioxide pass from the cells and
tissues into the blood stream
c. Veins
i. Carry deoxygenated blood away from the capillaries to the heart
ii. Veins also composed of three layers
1. Tunica externa, tunica media, tunica intima
a. Although these are the same as they are in an artery, the
layers are considerably less elastic and muscular
iii. Walls of veins are much thinner than artery walls
1. Do not have to withstand high internal pressures
iv. Veins have valves
1. These valves allow blood to flow only in one direction, toward the
heart
2. This prevents reflux or backflow of blood towards the capillaries
3. There are many valves in the lower extremities where blood had
to oppose the force of gravity
Circulation
1. Cardiopulmonary Circulation
a. Cardiopulmonary circulation takes deoxygenated blood from the heart to
the lungs where carbon dioxide is exchanged for oxygen
b. The oxygenated blood returns to the heart
i. Blood enters the right atrium, which contracts forcing the blood
through the tricuspid valve into the right ventricle
ii. The right ventricle contracts to push the blood through the
pulmonary valve into the pulmonary trunk
1. The pulmonary trunk then divides into two, bringing blood
into the right and left lung
c. Inside the lungs, the pulmonary arteries branch into countless small
arteries called arterioles
i. These arterioles connect to
dense beds of capillaries lying
in the alveoli lung tissue
1. Here, gas exchange
occurs
a. Carbon dioxide
leaves the red
blood cells and is
discharged into the
air in the alveoli to
be excreted by the
lungs
b. Oxygen from air in the alveoli combines with hemoglobin
in the red blood cells
i. From these capillaries the blood travels into small
veins or venules
ii. Venules from the right and left lungs form large
pulmonary veins. These veins carry oxygenated
blood from the lungs back to the heart and into the
left atrium
d. The left atrium contracts, sending the blood through the bicuspid valve,
into the left ventricle
e. This chamber then acts as a pump for newly oxygenated blood
i. When the left ventricle contracts, it sends oxygenated blood through
the aortic semilunar valve, then into the aorta
1. http://highered.mcgrawhill.com/sites/0072495855/student_view0/chapter25/animation__gas_ex
change_during_respiration.html
2. Systemic Circulation
a. There are four functions of systemic circulation
i. Circulate nutrients, oxygen, water, and secretions to the tissues and
back to the heart
ii. It carries products such as carbon dioxide and other dissolved
wastes away from tissues
iii. It helps equalize body temperature
iv. It aids in protecting the body from harmful bacteria
b. The aorta is the largest artery in the body
i. The first branch of the aorta is the coronary artery, which takes
blood to the myocardium (cardiac muscle)
ii. As the aorta emerges (ascending aorta) from the upper portion of the
heart, it forms an arch (aortic arch)
1. Three branches come from
this arch
a. Brachiocephalic
b. Left common carotid
c. Left subclavian
arteries
i. These carry
blood to the
arms, neck, and
head
c. From the aortic arch, the aorta descends along the mid-dorsal wall of the
thorax and abdomen
i. Many arteries branch off from the descending aorta, carrying
oxygenated blood throughout the body
d. As the descending aorta proceeds
posteriorly, it sends off additional
branches to the body wall,
stomach, intestines, liver,
pancreas, spleen, kidneys,
reproductive organs, urinary
bladder, legs and so forth
e. Each of these arteries subdivides
into smaller arteries, then
arterioles, and finally into
numerous capillaries embedded in the tissues
i. This is where hormones, oxygen, and other materials are transported
from the RBC’s and plasma to the tissues
ii. In turn, metabolic wastes and nitrogenous wastes are picked up by
blood capillaries
f. Deoxygenated venous blood, returning from the lower parts of the body,
empties into the inferior vena cava
i. Venous blood returning from the upper parts of the body empty into
the superior vena cava
1. Both superior/ inferior empty into the right atrium
Respiratory System
1. Functions
a. Provides the structures for the exchange of
carbon dioxide and oxygen in the body through
respiration, which is subdivided into internal
respiration, external respiration, and cellular
respiration
b. Responsible for the production of sound (larynx
contains vocal cords). When air is expelled
from lungs it passes over the vocal cords and
produces sound.
2. Respiratory Organs and Structures
a. Nasal cavity
i. Bones and cartilage support nose
ii. Two openings called anterior nares or nostrils
iii. Hair (cilia-like projections) filters
large particles
b. Pharynx
i. Behind oral cavity
ii. Between nasal cavity and larynx
iii. Broken down into three sections
1. Nasopharynx
2. Oropharynx
3. Laryngopharynx
c. Larynx
i. Enlargement at the top of the trachea and below the pharynx
ii. Conducts air in and out of trachea
iii. Houses vocal cords
1. Changing shape of the pharynx, and oral cavity changes sounds
into words
2. Contracting and relaxing muscles changes pitch (increased
tension = higher pitch)
d. Trachea
i. Windpipe
ii. Flexible cylinder, about 12.5
cm long
iii. Extends downward in front of
the esophagus
iv. Contains about 20 C-shaped
rings of hyaline cartilage that
prevent trachea from
collapsing
e. Bronchi and Bronchioles
i. Branched airways leading from the trachea to the air sacs (alveoli) in
the lungs
ii. Primary bronchi (left/ right) –to- bronchioles –to- alveolar ducts –toalveoli –then- gases are exchanged between alveoli and capillaries
f. Alveoli
i. Tiny air sacs
1. About 500 million/ adult lung
2. High surface area to volume ratio
3. Inner portion covered by fatty substance called surfactant
a. Helps to stabilize the alveoli, preventing them from
collapsing
g. Lungs
i. Soft, spongy, cone-shaped organs in the thoracic cavity
ii. Left lung- smaller, 2 lobes
iii. Right lung- larger than left, 3 lobes
h. Pleura
i. Thin, moist, slippery
membrane covering lungs
ii. Two pleura membranes
1. Visceral pleura
a. Attaches to each
lung surface
2. Parietal pleura
a. Lines thoracic
cavity
iii. Space between visceral and parietal pleura is called the pleural cavity
1. This space is filled with pleural fluid that prevents friction
between the two pleural membranes
3. Pathway of Oxygen to Lungs
a. External
i. Air enters through the nasal cavity
ii. Then to the pharynx
iii. Then to the larynx
iv. Then to trachea
v. Then to the bronchial tree
vi. Then to the bronchus
vii. Then to the bronchiole
viii. Then to the alveoli
4. Respiration
a. Is the physical and chemical processes by
which the body supplies its cells and tissues with the oxygen needed for
metabolism and relieves them of carbon dioxide formed in energy producing
reactions
b. Subdivided into external respiration, which takes place in the lungs, internal
respiration which takes place between the cells and blood, and cellular
respiration, which occurs in cells
i. External
1. Also known as breathing or ventilation
2. Exchange of oxygen and carbon dioxide between the lungs, body
and outside environment
3. The breathing process consists of inspiration (inhalation) and
expiration (exhalation)
a. Inspiration
i. Air enters body and is warmed, moistened, and
filtered as is passes to the alveoli. The concentration
of oxygen is greater here than in the blood stream.
Oxygen diffuses from the area of greater
concentration (alveoli) to an area of lesser
concentration (the blood stream), then onto the
RBC’s.
ii. At the same time, the concentration of Carbon dioxide
is greater in the blood stream than in the alveoli, so it
diffuses from the blood to the alveoli
c. Internal
i. Includes the exchange of carbon dioxide
and oxygen between the cells and the
lymph surrounding them, plus the
oxidative process of energy in the cells
ii. After inspiration, the alveoli are rich
with oxygen and transfer oxygen into
the blood
1. Results in greater concentration
of oxygen in the blood diffuses
the oxygen into the tissue cells
2. Wastes diffuse from cells to capillary blood stream
d. Cellular
i. Oxidation
ii. Involves the use of oxygen to release energy stored in nutrient
molecules such as glucose
1. This chemical reaction occurs within the cells
2. Ex.// Wood gives off energy in the form of heat as it burns, food
does too when it is oxidized or burned in the cells
iii. Much of this energy is released in the form of heat to maintain body
temperature
1. Some is used directly by cells for such work as contraction of
muscle cells or other vital processes