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6.2 The Transport System
1. Draw and label a diagram of the heart showing the four chambers, associated blood
vessels, valves and the route of blood through the heart.
2. State that coronary arteries supply heart muscle with oxygen and nutrients.
3. Explain the action of the heart in terms of collecting blood, pumping blood, and opening
and closing of valves.
A. the heart: composed mainly of contractile muscle tissue, supported by connective, nerve, and
epithelial tissues
B. collecting of blood:
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deoxygenated blood enters the right atrium from the inferior and superior vena cava
oxygenated blood enters the left atrium from the pulmonary vein
C. pumping of blood:
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contraction of the atria (right and left) pumps the blood into the ventricles (right and left)
contraction of ventricles (right and left) pumps the blood into the pulmonary artery(right) and
aorta (left)
D. opening and closing of valves:
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as a function of pressure differences, one-way valves prevent backflow of blood
atrioventricular valves prevent backflow from ventricles into atria
semilunar valves prevent backflow of blood from pulmonary artery into right ventricle and
from aorta into left ventricle
3. Outline the control of the heartbeat in terms of myogenic muscle contraction, the role of
the pacemaker, nerves, the medulla of the brain and epinephrine (adrenaline).
A. heartbeat: electrical impulses cause regular contractions of, first the two atria, and then the two
ventricles
B. pacemaker and myogenic muscle contraction:
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the sino-atrial node (SAN), known as the pacemaker, is a specialized set of cells located on
the right atrium
SAN, not the brain, generates regular electrical impulses autonomously
SAN impulses spread throughout both atria, causing simultaneous contraction
impulse spread to ventricles only at the atrio-ventricular node (AVN) with a delay of about 0.1
seconds
AVN transmits electrical signals to heart apex via bundles of His
signals trigger powerful contractions of both ventricles from the apex toward the atria
bundle of His transmits electrical signals throughout ventricles via Purkinje fibers, causing
simultaneous contraction of ventricles
C. nerve stimulation:


sympathetic nerves from brain release epinephrine, increasing heart rate
parasympathetic nerves from brain via vagus nerve decrease heart rate
D. hormone stimulation:

adrenaline (epinephrine) from adrenal medulla increase heart rate
5. Explain the relationship between the structure and function of arteries, capillaries, and
veins.
vessel
Artery
Structure
-inner endothelium
-thick walls of smooth
muscle with elastic
fibers
Function
move blood away from
heart under very high
pressure & high speed
(10-40 cm/sec)
-outer layer of
connective tissue with
elastic fibers
Veins
-inner endothelium
-thin walls of smooth
muscle with elastic
fibers
-outer layer of
connective tissue with
elastic fibers
move blood toward the
heart under very low
pressure fiber
(10 mm Hg) & moderate
speed (5-20 cm/sec)
-prevent backflow of
blood
-valves
-thin single layer of endothelium
of dissolved
capillary
& tissues
-surrounded by basement
membrane
-numerous
allow diffusion
materials between blood
under low pressure (20-
40 mm Hg)
& low speed (< 1 cm/sec)
6. State that blood is composed of plasma, erythrocytes, leucocytes (phagocytes and
lymphocytes), and platelets
7. State that the following are transported by the blood: nutrients, oxygen, carbon dioxide,
hormones, antibodies, urea and heat.