Anatomy Ch 15
Blood Vessels and Blood Circulation
A. Blood Vessels – 5 types of vessels
Type
1. Arteries
Structure
3 layer Thick-walled elastic;
middle layer smooth muscle
Function
Carry blood away from the heart
to the tissues
2. Arterioles
3. Capillaries
Thinner walls, less elastic
Smallest/thinnest vessels
connect arterioles to venules
Carry blood to capillaries
Allow for the exchange of gases
with the tissue cells
4. Venules
Smallest veins; thin walls
Receive blood from capillaries
and begin journey back to heart
5. Veins
3 layers but thinner than
arteries; one-way valves
Carry blood back to heart;
valves prevent backflow of
blood
B. Blood Circuits
a. Pulmonary circuit
i. Delivers blood to the lungs for gas exchange
ii. Oxygen in and Carbon dioxide out
b. Systemic Circuit
i. Supplies blood to rest of the body
ii. Brings nutrients and carries away wastes
C. Systemic Arteries – Branches off the aorta
a. Aorta is the largest artery; begins at top of heart and descends into abdominal cavity
b. Carotid arteries go to the head
c. Brachial arteries go to the arms
d. Iliac arteries go to the legs
D. Systemic Veins – Branches of the Vena Cava
a. Vena Cava is the largest vein; runs next to aorta
b. Jugular brings blood from the head
c. Brachial veins bring blood back from arms
d. Iliac veins return blood up from legs
E. Hepatic Portal system
a. Portal system is a pathway that detours blood between organs
b. Hepatic carries blood from abdominal organs to the liver
c. Liver processes stores and releases nutrients then returns blood to vena cava
F. Blood flow to the cells
a. Nutrients and oxygen leave the capillaries and enter cellular fluid
b. Wastes and carbon dioxide are picked up the same way
c. Both of these processes occur by diffusion
d. Heart beat force and gravity drives blood through arteries
e. Veins travel uphill with the help of skeletal muscles, valves and breathing
G. The Pulse
a. Ventricles pump 70-80 times per minute
b. Pressure of pump sends a wave through arteries that can be felt anywhere in body
c. Many factors can influence the pulse rate
i. Size/age of person
ii. Muscular activity
iii. Emotional state
H. Blood Pressure
a. Definition: - the force exerted against the walls of the vessels
b. Determined by
i. Heart (cardiac) output – the volume of blood pumped out of each ventricle in one
minute
ii. Resistance to blood flow inside the vessels (amount of friction)
c. Sphygmomanometer (blood pressure cuff) measures pressure
i. Systolic pressure occurs while heart is contracting (avg 120)
ii. Diastolic pressure occurs during relaxation of heart muscle (avg 80)
iii. Written systolic/diastolic……. 120/80mmHg
d. Hypotension is low blood pressure
e. Hypertension is high blood pressure
I. Blood Vessel Disorders
a. Arteriosclerosis – degeneration of blood vessels
b. Atherosclerosis – build up of plaque in vessels, can lead to thrombosis
c. Aneurysm – a bulging sac in the wall of a blood vessel that could rupture
d. Hemorrhage is a profuse loss of blood internally or externally
e. Shock – inadequate blood flow to tissues
f. Thrombosis – a blood clot within a vessel
g. Embolus – piece of a clot that breaks free and floats in the blood
i. Pulmonary embolism – clot in the lungs
ii. Stroke – clot in the brain
h. Varicose veins – swollen, distorted and ineffective veins
i. Hemorrhoids are varicose veins in the rectum