W9D2P1-Arterioles

baseline, increase, decrease, increase, decrease, increase, decrease

arterioles match blood flow with local tissue/cellular metabolic demand. What does this mean

at a ________ metabolism in cells, the arteriole has a given radius, resistance, and flow that then causes a baseline flow, volume, and pressure in the capillaries

if we increase the metabolism in cells, there will be an ________ in arteriole radius and flow, and a _______ in resistance that will cause an _______ in capillary flow, volume, and pressure

if we decrease the metabolism in cells, there will be a ________ in arteriole radius and flow, and an _______ in resistance that will _________ the flow, volume, and pressure through the capillaries

thick smooth muscle layer surrounding arterioles

what allows arterioles to regulate pressure and flow downstream (in capillaries)

local environment

cells being perfused and capillaries doing the perfusion

local factors

things that influence arterioles (O2, metabolic waste, acids, CO2)

1

how many capillary beds per arteriole

high, low, low, high, low, high

as you go through a capillary (starting at the arteriole and ending at the venule) how do the concentrations of O2, metabolic wastes, and CO2 change?

O2: ____ O2 at arteriole end, ___ O2 at venule end (diffused out of capillaries to the cells)

metabolic wastes: ___ at arteriole end, ____ at venule end (taken in my capillaries to be removed)

CO2: ___ at arteriole end, ____ at venule end (cells release CO2)

match blood flow to local tissue/cellular metabolic demand, collectively maintain the MAP by determining the TPR (need to protect MABP by TPR cooperation)

2 major functions of arterioles

heart, brain

management conflicts between the two functions of the arterioles:

conflict of skeletal muscle arterioles when you exercise on a hot day--> heatstroke example from week 1

_____ and ____ are more important for the survival of the individual so they take priority

TRUE

true or false: all vessels in the cardiovascular system contribute to resistance to blood flow

ARTERIOLES

____ are the site of greatest vascular resistance and are thus the main contributors to the total peripheral resistance (TPR)

total peripheral resistance

the total resistance to flow generated by the arterioles

one arteriole has resistance to flow--> all arterioles together have TPR to flow

MAP = CO x TPR

How does MAP related to TPR

changes in TPR directly cause changes in MAP

they have thick layers of smooth muscle which allows them to change their radius, this alters TPR

why do arterioles have the greatest control over blood flow?

by relaxation and contraction of circular smooth muscle in arterioles

How are dynamic adjustments in the blood distribution to the organs accomplished

vasodilate, vasoconstrict

how do arterioles match flow to local/organ demand

if an organ or cell needs more blood flow, then the arteriole will _______
if an organ or cell needs less blood flow, then the arteriole will _______

BRAIN AND HEART

these two organs always have constant blood flow (i.e. do not have a change in resistance of arterioles)

vasoconstrict

How do arterioles help protect MAP by TPR cooperation (ex: loss of pressure in arteries via hemorrhage)?

arterioles will __________ to help protect the mean pressure--> also!! protects the heart and the brain

even under these conditions, the heart and brain will still receive proper supply of blood

conditioning organs

receive blood flow in excess of their personal metabolic needs

very tolerant to blood flow reduction

arterioles to these organs are constricted to protect blood pressure

kidneys, intestines, skin

example of conditioning organs

flow dependent organs

critically dependent on blood flow for survival

no tolerance to ischemia or low blood flow

ARTERIOLES TO THESE ORGANS DO NOT CONSTRICT TO PROTECT BP--> these organs benefit

heart and brain

example of flow dependent organs

vasodilate, vasoconstrict, vasodilate, brain

example: arteriolar rearrangement of flow from resting to exercise

-skeletal muscle arterioles actively _________ and get more blood

-arterioles to organs that are not needed during exercise ___________ and get less blood

-skin arterioles _________ to cool the core (depends on external temp)

-_____ gets more blood mainly due to slight increase in blood pressure

CO, TPR, MABP

what happens to MABP, CO, TPR with exercise?

__--> BIG increase (SV and HR increase)

___--> big decrease (the dilation to skeletal muscle cells overrides the collective constriction to other organs)

____--> slight rise (largely due to large rise in CO)

TPR

arterioles determine

relaxing, contracting

dynamic adjustments in blood distribution to organs is done by ________ and _________ circular smooth muscle in arterioles