Blood Vessels 1 Flashcards by Tracie K

Arterioles are ___ vessels.

resistant

How well did you know this?

Not at all

Perfectly

Arterioles connect ____ to _____ or _______.

arteries to capillaries or metarterioles

How well did you know this?

Not at all

Perfectly

Arterioles contain ____ to regulate ____.

contain rings of smooth muscle to regulate radius and therefore resistance

How well did you know this?

Not at all

Perfectly

Changes in arteriole radius depends on:

contraction state of smooth muscle in arteriole wall

How well did you know this?

Not at all

Perfectly

Name 2 functions of varying arteriole radius.

controlling blood flow to individual capillary beds

- regulating MAP

How well did you know this?

Not at all

Perfectly

Contraction level (radius) of arterioles is _________ of extrinsic influences.

independent

How well did you know this?

Not at all

Perfectly

Vasoconstriction of arterioles =

increased contraction = decreased radius

How well did you know this?

Not at all

Perfectly

Vasodilation of arterioles =

decreased contraction = increased radius

How well did you know this?

Not at all

Perfectly

Regulation of blood flow to organs is based on ____. What is it regulated by?

based on need

- regulated by varying resistance

How well did you know this?

Not at all

Perfectly

Organ blood flow =

MAP/organ resistance

How well did you know this?

Not at all

Perfectly

What is regulated through changes in radius of arterioles?

vascular resistance

How well did you know this?

Not at all

Perfectly

Local factors regulate radius, thereby regulating blood flow. Give 3 examples.

carbon dioxide
potassium
hydrogen ions

How well did you know this?

Not at all

Perfectly

Changes associated with increased metabolic activity generally cause ______. This comes with increased levels of:

vasodilation
carbon dioxide
potassium
hydrogen ions

How well did you know this?

Not at all

Perfectly

Changes associated with decreased metabolic activity generally cause _____. This comes with increased levels of:

vasoconstriction

- oxygen

How well did you know this?

Not at all

Perfectly

What is active hyperemia?

increased blood flow in response to increased metabolic activity

How well did you know this?

Not at all

Perfectly

Describe O2 delivery and CO2 removal in steady state.

O2 is delivered as fast as it is consumed

- CO2 is removed as fast as it is produced

How well did you know this?

Not at all

Perfectly

Describe O2 delivery and CO2 removal during increased metabolic rate.

O2 is consumed faster than it is delivered

- CO2 is produced faster than it is removed

How well did you know this?

Not at all

Perfectly

Describe the response to low O2 and high CO2.

vasodilation
increased blood flow
delivers more O2
removes more CO2

How well did you know this?

Not at all

Perfectly

What is reactive hyperemia?

increased blood flow in response to a previous reduction in blood flow

How well did you know this?

Not at all

Perfectly

What is the response when there is a blockage of blood flow to tissues?

metabolites increase
oxygen decreases
causes vasodilation

How well did you know this?

Not at all

Perfectly

What is the response when the blockage of blood flow to tissue is released?

increased blood flow due to low resistance
metabolites removed
oxygen delivered

How well did you know this?

Not at all

Perfectly

Describe the negative feedback for active hyperemia.

TISSUES
- increase metabolic rate
- increased O2 consumption and CO2 production
- decreased O2 concentration, increased CO2 concentration
LOCAL ARTERIOLAR SMOOTH MUSCLE
- increased vasodilation
- decreased resistance
- increased blood flow
- increased O2 delivery and CO2 removal
- increased O2 concentration, decreased CO2 concentration
- neg. feedback to step 3 in tissue

How well did you know this?

Not at all

Perfectly

Describe the negative feedback for reactive hyperemia.

TISSUE
- decreased blood flow
- decreased O2 concentration, increased CO2 concentration
LOCAL ARTERIOLAR SMOOTH MUSCLE
- increased vasodilation
- decreased resistance
- increased blood flow
- increased O2 delivery, increased CO2 removal
- increased O2 concentration, decreased CO2 concentration
- neg. feedback to step 2 in tissue

How well did you know this?

Not at all

Perfectly

Describe the myogenic response to changes in perfusion pressure.

change in vascular resistance in response to stretch of blood vessels in the absence of external factors
intrinsic control

How well did you know this?

Not at all

Perfectly

What is perfusion pressure?

pressure gradient driving blood flow

Describe flow autoregulation.

- myogenic response maintains blood flow through the tissue bed - blood flow remains constant (local control)

Why is myogenic response interconnected with responses?

due to metabolite concentration

Describe neg. feedback for increased perfusion pressure in arteriole leading to decreased flow.

- increased perfusion pressure - increased stretch of arteriolar smooth muscle - increased constriction - increased resistance - decreased flow - neg. feedback to increased flow

Nitric Oxide (NO) is produced by _____ and causes ____.

- endothelial cells - relaxes narrowed blood vessels - increases oxygen and blood flow

Histamine is produced with ______ and causes _____.

- inflammatory response - dilation of blood vessels - increases permeability - lowers blood pressure

Endothelin-1 is produced by ______ and causes ______.

- endothelial cells | - vasoconstriction

Radius of arterioles is regulated by_______ mechanisms to control ____.

- extrinsic | - MAP

_____ innervates most arterioles.

SNS

What hormones play a role in the regulation of the radius of arterioles?

- epinephrine - vasopressin (ADH) - angiotensin II (part of the RAAS system)

Sympathetic innervation of ______ ______ of arterioles

smooth muscle

Smooth muscle of most arterioles (not those in brain) has __ _______ receptors.

α adrenergic receptors

________ binds to α adrenergic receptors, causing _____, which increases ____ and _____.

- Norepinephrine - vasoconstriction - increases TPR - increases MAP

There are both ___ and _____ adrenergic receptors in arterioles.

α and β2

______ binds to α and β2 receptors, causing _____ at α receptors and _______ at β2 receptors

- epinephrine - vasoconstriction at α receptors - vasodilation at β2 receptors

α and β2 receptors dominate in ____ and _____ tissue.

skeletal and cardiac

Epinephrine is released by both:

- SNS stimulation | - adrenal medulla

What are the effects of epinephrine on arteriole radius in lower concentrations?

- binds β2 | - vasodilation

What are the effects of epinephrine on arteriole radius in higher concentrations?

- binds α and β2 - Vasodilation in skeletal and cardiac muscle vascular beds = Decreases TPR → decreases blood pressure - Vasoconstriction in most vascular beds = Maintains/increases TPR → maintains blood pressure

Dominant effect of epinephrine on arteriole radius is usually:

vasoconstriction (whole body)

Distribution of blood does not increase proportionally, meaning:

- Dilation of vessels to skeletal muscle and heart increases blood flow to muscles - Constriction of vessels to GI tract and kidneys decreases blood flow to these organs - Disproportionate flow diverts blood to muscles

Epinephrine is released from:

adrenal medulla

Vasopressin (ADH) is secreted by ____ and does:

- secreted by posterior pituitary - increases water reabsorption by kidneys, limits urine output - vasoconstriction

Angiotensin II does what in plasma? What does it do overall?

- precursor in plasma, interacts with vessel wall - vasoconstriction - increases TPR

What is the purpose of capillaries?

site of exchange between blood and tissue

How many capillaries per body? What is the total SA?

- 10-40 billion per body - total SA = 600 m^2 - most cells within 1 mm of capillary - 1 mm long

What is the function of pores between endothelial cells?

protein-free plasma moves through pores

Describe diffusion distance in capillaries.

- 5-10 mm in diameter | - small diffusion distance

Describe the walls of capillaries.

- one cell layer - small diffusion barrier - have greatest total cross-sectional area - have slowest velocity of blood flow, which enhances exchange

List the vessels from smallest to largest total cross-sectional area.

- aorta - arteries/veins - arterioles/venules - capillaries

What are the 4 types of capillaries?

- continuous - fenestrated - discontinuous - sinusoids

Describe continuous capillaries.

- most other tissues - most common - small gaps between endothelial cells - small gaps allow small water-soluble molecules to move through

Describe fenestrated capillaries.

- kidneys, intestines - large gaps between endothelial cells forming pores/fenestrations (windows) - large gaps allow proteins, and in some cases blood cells to move through

Describe discontinuous capillaries.

- spleen, bone marrow, liver - transition between fenestrated to sinusoids - proteins and cells need to cross - discontinuous form sinusoids

Describe sinusoids capillaries.

- formed from discontinuous (same organs) - large spaces filled with blood - exchange between blood and tissues - ie. RBCs from marrow to circulation

Describe the structure of metarterioles.

- intermediate between arterioles and capillaries | - directly connect arterioles to venules

What is the function of metarterioles?

function as shunts to bypass capillaries

What do the rings of smooth muscle do on metarterioles.

- at strategic locations - contract and relax in response to local factors - contract: decrease blood flow through capillaries - relax: increase blood flow through capillaries

What are pre capillary sphincters?

rings of smooth muscle that surround capillaries on the arteriole end

Pre capillary sphincters contract and relax in response to ____ _____ only.

local factors

Contraction of pre capillary sphincters causes:

- constriction of capillary | - decreased blood flow

Relaxation of pre capillary sphincters causes:

increased blood flow

What causes relaxation of pre capillary sphincters?

metabolites