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Lecture

Chapter 6 Textbook Notes


Department
Health Studies
Course Code
HLTC22H3
Professor
Anna Walsh

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Chapter 6- Aging of the Internal Organ Systems
Cardiovascular System
Basic Anatomy and Physiology
Main transportation system
Sends supplies such as fluids, nutrients, hormones, oxygen and antibodies to the tissues in
the body and also removes waste products like carbon dioxide and hydrogen ions
Composed of : heart, blood vessels (arteries, arterioles, capillaries, veins and venules) and
blood
Arteries- carry blood away from heart
Veins- carry blood to the heart
Blood is composed of: water, red and white blood cells and platelets; as well as, fat
globules, carbohydrates, and proteins
It is perfused by: gases (oxygen, carbon dioxide, and nitrogen)
Blood also carries electrolytes and helps maintain acid/base balance
Also carries, hormones, neurotransmitters and other peptides that are necessary for
homeostasis, cognition, movement and other functions of the body
Heart is the in the center of the circulatory system; located behind the chest wall in a
canted position with the midsection somewhat to the left of the breastbone; enclosed in a
sac called the pericardium
Left and right sides have two upper chambers (atria); atria are thin walled: collect blood
Left and right lower chambers (ventricles); thicker walls and more muscular for long
distance pumping: pump blood to the lungs and rest of the body
Left and right sides of the heart serve as a pump
Oxygen poor blood is collected in the right atrium from large veins (superior and inferior
vena cava)
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Next, it flows to the right ventricle and is pumped by the pulmonary arteries into the
capillary system of the lungs for CO2 and O2 exchange
O2 rich blood is sent via pulmonary veins into the left atrium Left ventricle pumped
out through the aorta
From aortagoes to large arteries and small arteries, arterioles and capillaries
Capillaries- small in size and ensure that all cells in the body have access to blood stream
Fluids, nutrients, electrolytes, hormones and other substances are exchanged in capillaries
Venules collect blood from capillaries and more it into the larger veins until it reaches
superior and inferior vena cava
Veins- 64% of blood volume is found within them
Walls of arteries and veins is composed of smooth muscle, elastic fibers and collagen
Nerve cells regulate expansion and contraction of blood vessels
Valves from atria to ventricles serve to control the timing and amount of blood flow
Left and right sides of heart have no direct connection therefore, O2 rich and poor blood
cant mix
Timings of the pumps are coordinated
Beat starts in the pacemaker (sinoatrial node) in the upper right atrium signal spreads
down the heart though the atrial myocardium to reach the atriventrivular node impulse
is conducted to purkinje fibers where its sent to both ventricles
As signal moves down, contraction of heart muscle occur
Systole= contraction of heart
Diastole= relaxation of heart
Asystole= no heart beat
Lub= first and loudest sound of a heartbeat; when valves between atria and ventricles
closes and ventricles contract
Dub= softer beat; second; occur with closure of the valves between the ventricles and
large arteries (pulmonary and aorta)
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Pulses can be felt at different areas of the body
1) Carotid pulse (on the neck)
2) Radial pulse (outer edge of wrist)
3) Pedal pulse (top of foot)
4) Popliteal pulse (back of the knee)
Veins are reservoirs for blood; to help blood keep moving and preventing it from pooling
in extremities, some veins have valves (i.e great saphenous found in the back of the legs)
Valves consist of tissue inside the vein wall that extends into the vein (flapper valve)
forcing blood to move in one direction
Venous blood seen in distended veins of hands and feet
If a person stands still for 15 mins, venous pumps( flapper valves and veins) work less
efficiently; may lead to abnormal blood flow to upper part of body
Constriction of veins damage of a vessel and possibly formation of blood clots
rate of blood flow determined by physical demands on the body; heart alters its rate
depending on external and internal demands
stimulation to decrease and increase the heart rate is determined by autonomic nervous
system( sympathetic NS- increases rate and strength of heartbeat and parasympathetic-
decreases the rate and strength)
the cardiovascular system serves as a conduit for communication among the organs
Age related changes
few normal changes that occur with age
normal enlargement of heart mass because of increase in size of the myocytes (muscle
cells)
slowing of electrical activity of the heart
by age 75- only about 10% of pacemaker cells remain
increase in amount of fat tissue around the sinoatrial node- interferes with conduction
system leading to abnormally slow pulse, referred to as bradycardia; treated by giving an
artificial pacemaker that keeps heart from falling below a preset rate
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