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Cardiovascular System Purpose Mammalian heart structures and function Blood Pressure Heart beat or rhythm Heart attacks and atherosclerosis Evolution of cardiovascular system

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Cardiovascular System • Purpose • Mammalian heart structures and function • Blood Pressure • Heart beat or rhythm • Heart attacks and atherosclerosis • Evolution of cardiovascular system

Cardiovascular System • All cells need

– Nutrients – Gas exchange – Removal of wastes

• Diffusion alone is inadequate for large and complex bodies

• Most animals use a circulatory system – Blood – Heart – Blood vessels

The mammalian heart – Two thin-walled atria that pump blood to ventricles – Thick-walled ventricles that pump blood to lungs and all other

body regions Right atrium To lung

From lung

Semilunar valve

Atrioventricular (AV) valve

Left atrium

To lung

From lung

Semilunar valve

Atrioventricular (AV) valve

Right ventricle

Left ventricle

Blood Anatomy and Circulation http://www.youtube.com/watch?v=H04d3rJCLCE

Flow through the Heart https://www.youtube.com/watch?v=7XaftdE_h60 7.5 mins

Superior vena cava

Pulmonary artery

Capillaries of right lung

8

9

2

3

Aorta

4 5 10

1 6 Pulmonary vein

9 Right atrium

Inferior vena cava

Right ventricle

4

8

3

Pulmonary artery

Capillaries of left lung

Aorta

Pulmonary vein

Left atrium

Left ventricle

2 7

Capillaries of head, chest, and arms

Capillaries of abdominal region and legs

Blood pressure and velocity reflect the structure and arrangement of blood vessels

Blood pressure and velocity is a reflection of the heart and blood vessels function in blood circulation

Rhythmic heart contractions and relaxations http://www.sumanasinc.com/webcontent/animations/content/bloodpressure.html

Blood pressure – The force blood exerts on vessel walls – Depends on

– Cardiac output – Resistance of vessels

– Decreases as blood moves away from heart Understanding Blood Pressure – Anatomy

http://www.youtube.com/watch?v=qWti317qb_w

• Blood pressure is – Highest in arteries – Lowest in veins

• Blood pressure is measured as – Systolic pressure—pressure caused by contraction

ventricles – Diastolic Right and left ventricles relax

Lub Dub https://www.youtube.com/watch?v=-4kGMI-qQ3I

Semilunar valves closed 1 Heart is

relaxed.

AV valves are open.

Diastole

0.4 sec

2 Atria contract.

Systole 0.1 sec

Semilunar valves are open.

3 Ventricles contract.

AV valves closed

0.3 sec

An internal pacemaker sets the tempo of the heartbeat

The heart contracts and relaxes rhythmically under the

effect of electrical signals received though nerves from the

• pacemaker (SA node) which generates electrical signals in right atrium

• AV node then relays these signals to the ventricles

Cardiac conduction system and ECG.wmv https://www.youtube.com/watch?v=RYZ4daFwMa8

Pacemaker (SA node) AV node

Right atrium

1 Pacemaker generates signals to contract

2 Signals spread through atria and are delayed at AV node

ECG

3 Signals relayed to apex of heart

4 Signals spread through ventricle

Apex

Specialized muscle fibers

Cardiac Conduction System http://www.youtube.com/watch?v=Lt092HZCppo

depolarization of the heart’s atria depolarization

of the heart’s ventricles

Re-polarization of the ventricles

https://www.youtube.com/watch?v=lRHq7sMRWpU

What is a heart attack? • A heart attack is damage to cardiac muscle

typically from a blocked coronary artery • Stroke- Death of brain tissue from blocked

arteries in the head

Blockage

Dead muscle tissue

Right coronary artery

Superior vena cava

Pulmonary artery

Aorta

Left coronary artery

What is a heart attack?

• Atherosclerosis – Plaques develop inside inner walls of blood vessels – Plaques narrow blood vessels – Blood flow is reduced

Plaque Epithelium Connective tissue

Smooth muscle

Evolution of Vertebrate Cardiovascular systems • Aquatic Organisms Two-chambered heart (Fish) Pumps blood in a single circuit

– From gill capillaries – To systemic capillaries – Back to heart

Gill capillaries

Heart: Ventricle (V)

Atrium (A)

Systemic capillaries

Land vertebrates have double circulation Separate pulmonary and systemic circuits

• Three-chambered hearts (Amphibians, turtles, snakes, lizards)

• Four-chambered hearts (Crocodilians, birds, mammals) Two atria and two ventricles

– Right side pumps blood from body to lungs – Left side pumps blood from lungs to body

Higher blood pressure – Supports more efficient movement of blood – Needed in endothermic animals

Lung and skin capillaries

Pulmocutaneous circuit

V Right

Systemic capillaries

A A

Left Systemic

circuit

Lung capillaries

Pulmonary circuit

V Right

Systemic capillaries

A A

Left Systemic

circuit

V