Circulatory System Flashcards
Functions of Circulatory System
- efficient distribution of gases and nutrients
- transport hormones and immune cells
- regulation of body temperature
3 main layers to a blood vessel:
- tunica externa (elastic collagen fibers)
- tunica media (smooth muscle)
- tunica intima (simple squamous epithelium)
Order through vein & artery size from the heart.
heart -> elastic artery -> muscular artery -> arteriole -> capillary bed -> venules -> medium-size veins -> large veins
What does an artery have that a vein does not?
- blood away from heart
- narrow lumen
- tunica media thick
- retain shape w/o blood
- more elastic & collagen fibers
- higher blood pressure
What does a vein have that an artery does not?
- blood to heart
- wide lumen
- tunica externa thick
- collapse without blood
What layers do capillaries have?
capillaries are only tunica intima
What are examples of elastic arteries?
- aorta
- pulmonary arteries
- brachiocephalic arteries
Elastic artery:
- high pressure areas (blood just came out)
- 1-2.5 cm in diameter
- elastic fibers in all tunics
- expand and recoil for continuous blood flow
Muscular arteries example
brachial and coronary arteries
Muscular arteries:
- thick tunica media
- elastic fibers in internal and external elastic membranes
Arterioles:
- 3mm - 10um diameter
- vasoconstrict and vasodilate to control blood flow into capillaries
What happens to the tunica media in vasodilation?
tunica media relaxes
What happens to the tunica media in vasoconstriction?
tunic media contracts
What is the outside layer of a capillary?
basal lamina
What does a capillary lack?
tunica externa & media
Why do the capillaries have a thin wall and narrow diameter?
SA:Vol (water hose) - slows down over broad area which allows more time for diffusion
How do RBCs pass through capillaries?
single file (capillaries barely bigger than a single RBC)
3 types of capillaries and locations of each:
- continuous (blood-brain barrier)
- fenestrated (choroid plexus & glomerulus)
- sinusoid (liver)
a- smooth muscle fibers
b- endothelium
c- pre-capillary sphincter
d- true capillaries
e- thoroughfare channel
f- endothelium
Transport in continuous capillaries
- diffusion through membrane (lipid-soluble)
- transport via vesicles or caveola (large)
- have tight junctions & desmosomes
Transport in fenestrated capillaries
movement through fenestrations (water-soluble)
Transport in sinusoidal capillaries
movement through intercellular clefts (water-soluble)
What type of capillaries from left-right:
- continuous
- fenestrated
- sinusoidal
What are arterioles companion vessels?
venules
Where do venules receive blood from?
capillaries
What 2 things help blood to continuously flow to the heart in the veins?
- valves for 1-way flow
- locomotion moves venous blood in addition to pressure
What can happen if there are unhealthy valves in veins?
varicose veins
What are risk factors for varicose veins?
- pregnancy
- constipation
- standing occupations
What veins lack valves?
- thoracic
- abdominal
- breathing=respiratory pump
What depends on the total cross-sectional area?
velocity of blood flow
What are the basics of fish circulatory system?
1-circuit
2- chambered
What is a true chamber?
atrium or ventricle