3.3 Circulation Flashcards by Jenna Wahler

Hemodynamics

Circulation of blood in the vasculature

How well did you know this?

Not at all

Perfectly

What matters in maintaining blood flow?

Hydrostatic pressure and Mean arterial pressure

How well did you know this?

Not at all

Perfectly

Hydrostatic pressure

Fluid physics, you need a driving force causing liquid blood to flow through the vascular tubing in all the tissues

How well did you know this?

Not at all

Perfectly

Mean Arterial Pressure

“Average blood pressure”

Essential to maintaining adequate volume of blood circulation and perfusion of all tissues

How well did you know this?

Not at all

Perfectly

MAP =

[(2 x diastolic) + systolic] / 3

How well did you know this?

Not at all

Perfectly

Normal MAP

80-90 mm Hg

How well did you know this?

Not at all

Perfectly

Why is normal MAP closer to diastolic?

Because we spend so much more time in diastole

How well did you know this?

Not at all

Perfectly

MAP =

CO x SVR

How well did you know this?

Not at all

Perfectly

Systemic Vascular Resistance

Pressure component of MAP that is dependent on the vasculature
(controlled through vasoconstriction and vasodilation)

How well did you know this?

Not at all

Perfectly

SVR increases / decreases depending on..

1) Volume of entire vasculature

2) Blood Viscosity

How well did you know this?

Not at all

Perfectly

Volume is a function of

Total length of vascular system

- Diameter of vessels in the system

How well did you know this?

Not at all

Perfectly

Larger diameter of vessels would lead to…

Lower resistance, lower back pressure

How well did you know this?

Not at all

Perfectly

Blood viscosity

Thickness of the blood

How well did you know this?

Not at all

Perfectly

What are vasculature lined with? (inside)

Endothelium comprised of endothelial cells

How well did you know this?

Not at all

Perfectly

Elastic arteries

Largest arteries, lots of elastic tissue

How well did you know this?

Not at all

Perfectly

What do elastic arteries do?

Stretch during ventricular systole

- Recoil during diastole

How well did you know this?

Not at all

Perfectly

What underlie the blood pressure measurement?

Stretch and recoil of elastic arteries

How well did you know this?

Not at all

Perfectly

How does elasticity relate to high blood pressure in diabetics?

Too much sugar in blood hardens elastic arteries, blood going through never gets “tamped down” by elasticity of arteries

How well did you know this?

Not at all

Perfectly

Muscular arteries

Medium sized arteries that branch from aorta, more smooth muscle than elastic tissue

How well did you know this?

Not at all

Perfectly

Arterioles

Small arteries with vascular smooth muscle, involuntary yet highly regulatable

How well did you know this?

Not at all

Perfectly

What do resistance vessels do?

They play a key role in rapidly changing SVR to respond to local tissue metabolic demands and the autonomic nervous system

What must larger arteries and arterioles do?

Reduce pulses of pressure and fast moving blood before entering capillaries

How does blood enter capillaries?

Smooth, laminar (even, no systole or diastole) flow

Capillaries

Single endothelial layer thick

Site of “capillary exchange” by diffusion (and pinocytosis)

Blood moves slowest in capillaries due to..

1) Arterioles | 2) Massive "total cross sectional area'

Veins

- Lowest pressure - One way valves - Walls contain minimal vascular smooth muscle (but can still constrict - Highly compliant

Compliance

"Stretchiness" in the walls of vessels.. small change in pressure leads to large change in volume

At rest, where is a majority (64%) of our blood?

Systemic veins and venues!

3 ways to mobilize the blood out of storage (veins) during exercise

1) Venoconstriction 2) Muscle activity 3) Valves

Venoconstriction (during exercise)

Sympathetic tone --> Contraction of smooth muscle surrounding veins --> decreases venous increases return of blood to the heart

What does an increase in return of blood to the heart cause and what is it due to?

Increases CO | Frank-Starling Law

Two components of muscle capacity in venous return

a) Contraction and movement of skeletal muscles | b) Respiratory pump

How do valves in the vein help during exercise?

Allow for no back flow of blood

Capillary exchange

How molecules move from blood to interstitial fluid and ultimately into cells

Primary and secondary routes of capillary exchange

Diffusion | Pinocytosis

Filtration

Water and some solutes from blood to interstitial space

Reabsorption

Water and some solutes from interstitial space back into blood

Forces driving filtration and reabsorption

1) Hydrostatic pressure | 2) Osmosis

What is the hydrostatic pressure in capillary coming in and going out?

35 mm Hg | 16 mm Hg

What is the hydrostatic pressure in the interstitial fluid?

ZERO

Osmosis can also be called...

Osmotic pressure of Colloidal osmotic pressure

What exerts vital osmotic pressure to counteract hydrostatic pressure?

Plasma proteins (liver albumin)

Does the interstitial space have a high or low osmolarity?

Very low, drives the liquid back into the "salty" blood

What is the net filtration when combining filtration and reabsorption?

14 + (-5) = 9mmHg net filtration OUT

What does the blood hydrostatic pressure do going through a capillary?

Plummets

What does the blood colloidal osmotic pressure do going through a capillary?

Holds steady at 26 mmHg between beginning and end of capillary

Interstitial COP is..

At a constant 5 mmHg

What happens to the extra "net filtrate"?

Picked up and moved by the lymphatic system and eventually returned to circulatory system

Lymphatic capillaries

Origin of lymph, low protein liquid filtrate that leaves blood capillaries and becomes interstitial fluid

Key features of lymphatic capillaries

"One-way door" | Anchoring filaments that are responsive to interstitial fluid accumulation