Circulation and Gas Exchange

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The superior vena cava and inferior vena cava flow into the Right Atrium - RA.

Slide 24

mammalian cardiovascular system

Superior vena cava

Returns deoxygenated blood from

body to heart RA

Pulmonary artery

Capillaries

of right Lung

GAS EXCHANGE

3

7

3

8

9

2

4

11

5

1

10

Aorta

Pulmonary vein

Right Atrium

RA - Receives deoxygenated blood

from body

Right Ventricle

RV - Pumps blood to lungs

Inferior vena cava

Returns deoxygenated blood from

body to heart RA

Capillaries of

abdominal organs and hind limbs

EXCHANGE with body cells

Pulmonary vein

Carries oxygenated blood

to heart: LA

Left Atrium - LA

Receives oxygenated blood

from lungs

Left Ventricle - LV

Pumps oxygenated blood to body

Aorta = main artery to body

for Systemic Circulation

Capillaries

of left Lung

GAS EXCHANGE

Pulmonary artery

Carries deoxygenated blood to lungs

Capillaries of head and

Forelimbs - EXCHANGE

Slide 25

The Mammalian Heart: A Closer Look

A closer look at the mammalian heart provides a better understanding of double circulation.

RIGHT side = deoxygenated blood from body pumped to lungs.

LUNGS = gas exchange.

LEFT side = oxygenated blood from lungs pumped to body.

Slide 26

Mammalian Heart

Pulmonary artery

- to lungs

Right Atrium RA

Receives

Deoxygented

Blood from

body

Semilunar

valve

Atrioventricular

valve

Right Ventricle RV

Pumps to lungs for

gas exchange

Left Ventricle LV

Pumps oxygenated

blood to body via aorta

Atrioventricular

valve

Left Atrium LA

Receives oxgenated

blood from lungs

Semilunar

valve

Pulmonary veins -

from lungs to heart

Aorta - systemic

circulation

Slide 27

The heart contracts and relaxes in a rhythic cycle called the cardiac cycle.

The contraction, or pumping, phase is called systole.

The relaxation, or filling, phase is called diastole.

Blood Pressure = systolic / diastolic

Slide 28

Cardiac cycle

Semilunar

valves

closed

0.4 sec

AV

valves

open

Atrial and

ventricular

diastole

1

2

0.1 sec

Atrial systole;

ventricular

diastole

3

0.3 sec

Semilunar

valves

open

AV valves

closed

Ventricular systole;

atrial diastole

Slide 29