Circulatory System Flashcards
Which vessels move blood away from the heart?
arteries
Which vessels bring blood back to the heart?
veins
In which vessels does nutrient exchange occur?
capillaries
What are the three layers of blood vessel walls (interior –> exterior)?
tunica intima, tunica media, tunica externa
What is the space where blood flows through the vessel called?
lumen
Which layer of the blood vessel is absent in smaller vessels?
tunica externa
Which layer contains an abundance of collagen, elastin, and neurons?
tunica externa
What is the purpose of the small blood vessels found in the tunica externa of large vessels?
supply nutrients
What type of tissue is the tunica intima comprised of?
simple squamous epithelial
What type of tissue is the tunica media comprised of?
smooth muscle
What is the name of the structure that controls blood flow into capillary beds?
pre capillary sphincters
Why are the pre capillary sphincters important?
if there was blood flow through the capillaries all the time, your body would essentially run out of blood. there isn’t enough for it to be flowing everywhere all the time so being able to constrict the vessel is crucial
What are the vessels found in the venous system (small –> big)?
venules and viens
Why do veins have a larger lumen than arteries?
so there is less resistance to flow
What causes the valves in veins to shut?
blood movement in the wrong direction
What are the two pumps that push blood in the correct direction through the veins?
skeletal muscle pump and respiratory pump
What is the job of the skeletal muscle pump?
propel blood out of the limbs using micro contractions over time
What is the job of the respiratory pump?
moves blood in abdomen into heart/thoracic cavity
How does the respiratory pump work?
works as long as your breathing, diaphragm creates pressure differences
What is circulation?
amount of blood flow in a minute
Describe global circulation.
flow through the whole body in one minute (aka cardiac output)
Describe regional circulation.
flow through a certain part of your body (kidney, etc)
Describe local circulation.
flow through a single capillary (or other vessel)
How do you calculate flow?
flow=change in pressure/resistance
What is resistance?
opposition to blood flow
What are factors that influence resistance?
vessel diameter, turbulence, vessel length, viscosity of blood
How does vasodilation affect blood flow?
decreases resistance; increases flow
How does vasoconstriction affect blood flow?
increases resistance; decreases flow
What causes turbulence?
branches in vessels or buildup of plaque/cholesterol
Why is obesity a cause of hypertension?
longer vessel=more resistance; when you gain weight, longer vessels are formed to supply nutrients to new vessels
What is a normal blood pressure?
120/80
What constitutes hypertension?
BP > 140/90
What can cause your blood pressure to temporarily rise?
exercise, fever, anger
What constitutes hypotension?
BP < 90/60
What is orthostatic hypotension?
when you stand up to quickly causing your blood pressure to drop instantly
What is circulatory shock?
extremely low blood pressure that is usually caused by blood loos, extreme dehydration, or an immune response
Which types of immune responses lead to circulatory shock?
anaphylactic shock (allergen) and septic shock (bacterial infection in the blood)
What happens to your vessels when you go into circulatory shock?
systemic dilation… all your vessels dilate at the same time and blood ultimately stops moving (treated with epinephrine to cause constriction)
What are baroreceptors?
receptors that measure BP at different places in the body
What do aortic arch baroreceptors measure?
BP to your body
What do carotid baroreceptors measure?
BP to your brain (more crucial)
What happens if the BP in your brain is too low?
syncope (fainting)
Which hormones cause BP to rise?
norepinephrine, epinephrine, angiotensin II, aldosterone
Which hormone decreases BP?
atrial natriuretic peptide (ANP)
When there is more blood in the system is there more or less H2O present?
more
How do kidneys affect blood pressure?
decide whether to push salt into urine or blood… water follows salt so if your body needs more blood it will push salt into blood and vice versa
