Design and Organization of Cardiovascular System Flashcards Preview

Block 2: Cardio, Renal, and Respiratory > Design and Organization of Cardiovascular System > Flashcards

Flashcards in Design and Organization of Cardiovascular System Deck (28):
1


Capillaries


6um diameter

Single layer of endothelial cells

Thin wall, non-muscular

Nutrients, gases, water, solutes exchanged btwn blood and tissues

Not all capillaries perfused with blood at all times (depends on dilation/constriction of precapillary sphincters and arterioles)

In metabolically active tissue (heart, kidney, lung) there is essentially no diffusion distance of interstitum between capillary and cell. Can be 4 to 6 capillaries next to every cell.

2

Pre-capillary arterioles

Small muscular (30-40um diameter)

Can vasoconstrict using pre-capillary sphincters

Constriction has large effect on vascular resistance, and thus flow

(Constriction of arteries has small effect on flow)

 

3


What regulates input flow? Output flow?


Input flow: pre-capillary sphincteric action

Output flow: venous muscular tone and systemic venous pressure

4


Capacitant chambers (right and left atria)


Thin walled

Easily distensible

Minimally contractile

Roughly spherical

5


Muscular band (right and left ventricle)


Continuous band of muscle fibers, attached with fibers aligned linearly

Functions as syncitium

Runs from beginning of pulmonary artery to base of aorta

6


Cardiovascular circuit (path of blood flow)


1) Lungs

2) Pulmonary vein

3) LA

4) Mitral valve (bicuspid)

5) LV

6) Aortic valve

7) Aorta

8) Body

9) Vena cava

10) RA

11) Tricuspid valve

12) RV

13) Pulmonary artery

14) Lungs

7


Circulations in series


Left heart and right heart function in series (left to systemic circulation to right to pulmonary circulation)

Blood vessels within a given organ are in series

Rt = R1 + R2...

Flow through each level of system is the same

Pressure decreases progressively

8

Cardiac output


Rate (flow) at which blood is pumped from either ventricle

CO = HR x SV

CO is L/min

(CO of left ventricle = CO of right ventricle)

CO = VR

9


Venous return


Rate at which blood is returned to atria from veins

(VR to right = VR to left)

VR = CO

10


AV valves vs. Semilunar valves


AV valves: between atria and ventricles (mitral and tricuspid); chordae tendineae connected to papillary muscles which prevent backflow of blood

Semilunar valves: from ventricle to artery (aortic and pulmonary); scoop-like flaps w/no chordae tendinae or papillary muscles

11


Change of blood flow to an organ system


1) CO constant but blood flow redistributed by selective alteration of arteriolar resistance

2) CO increases or decreases but percentage distribution of blood flow among organ systems constant (everything affected)

3) Combination of the first two: CO and percentage distribution of blood flow altered

12


Arteries


Thick walled

Elastic tissue, smooth muscle and connective tissue

Volume in arteries called "stressed volume"

Largest artery is the aorta

13


Arterioles


Smallest branches of arteries

Have highest resistance to blood flow

Site where resistance can be changed by alterations in sympathetic nerve activity

Smooth muscle innervated by sympathetic alpha1-adrenergic receptors (vasoconstriction) and beta2-adrenergic receptors (vasodilation)

 

 

14

Venules


Thin-walled

Smaller than veins

After capillary and before vein

15


Veins


Endothelial cell layer and some elastic tissue, smooth muscle and connective tissue (but less than arteries)

Large capacitance (capacity to hold blood) and contain largest percentage of blood in cardiovascular system

Smooth muscle innervated by sympathetic nerve fibers

Volume of blood in veins called "unstressed volume"

16

Velocity of blood flow (v)

v = Q/A

 

v = velocity of blood flow (cm/sec)

Q = flow (mL/sec)

A = cross-sectional area (cm2)

Note: use cross-sectional area of ALL capillaries added up; now you see that blood flows faster through aorta than through capillaries

17


Ohm's Law (for flow)


Q = delta P/R

 

Q = Flow (mL/min)

delta P = Pressure difference (mmHg) = MAP - MVP

R = Resistance (mmHg/mL/min)

18


Poiseuille equation


R = (8nl)/(pir4)

 

R = Resistance

n = Viscosity of blood

l = Length of blood vessel

r = radius of blood vessel

19


Circulation in parallel


Organ systems function in parallel via arteries so blood simultaneously delivered to brain, kidneys, etc.

1/Rt = 1/R1 + 1/R2...

Flow through each organ system is different (a percentage of the total

Pressure is the same as it started and in each organ system

20


Blood distribution in circulation


14% in arteries (20% in pulmonary arteries)

6% in capillaries (40% in pulmonary capillaries)

64% in veins (6% in pulmonary veins)

21


S1


Mitral and tricuspid valves close

Right before systole

Heard loudest at mitral area

22


S2


Aortic and pulmonary valve close

Right before diastole

Heard loudest at left sternal border

23


S3

VOLUME

During rapid ventricular filling of diastole

Increased filling pressure and when you have dilated ventricles

24


S4


STIFF WALL

"atrial kick"

During late diastole when atria contract, blood is ejected into stiff ventricular wall

Associated with ventricular hypertrophy

25


a wave of JVP


Atria contract

Push some pressure back into jugular vein

26


c wave of JVP

RV contracts

Closed tricuspid valve bulges back into RA and pushes pressure back into jugular vein

27

v wave of JVP


Filling of RA against closed tricuspid

Increases RA pressure, back to jugular vein

28


S2 splitting


Aortic valve closes before pulmonic

Inspiration increases difference because decreased thoracic pressure increases venous return to right heart, so fills more and takes longer for pulmonic valve to close