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
Diffusion of molecules
Capillary
Interstitial fluid
Tissue cell
https://www.youtube.com/watch?v=q0s-1MC1hcE
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