18. Heart and Circulatory System

Question 1

How much does the human heart weigh?

Answer 1

250-450g

Question 2

How many times does the heart beat a day?

Answer 2

~100 000/day

Question 3

How much blood does it pump? (/beat and/day)

Answer 3

~70mL/beat, ~7200L/day

Question 4

How many times does it circulate blood in a day?

Answer 4

1300 times a day?

Question 5

How many times does the heart beat + how much blood is pumped? (<1 second, 1 min, 1 day, 1 year, 70 years)

Answer 5

<1 second - 1 beat, 70ml
1 minute - ~70 beats, 5L
1 day - 100 000 beats, 7200L
1 year - 38 million beats, 2.6 million L
70 years - 2.5 billion, 184 million L

Question 6

What are the two muscles that support the double pump?

Answer 6

Atrial musculature, Ventricular musculature

Question 7

Are the atrial muscles and ventricular muscles thin.

Answer 7

Atrial muscle: thin
Ventricular muscle: thick and strong

Question 8

How are tendons arranged and why are they arranged like that?

Answer 8

Bundles of collagenous fibers arranged in parallel.
They are arranged this way to form cords which have great tensile strength.

Question 9

What is the function of tendons?

Answer 9

To anchor or bind muscles to bones.

Question 10

What does the septa do?

Answer 10

Prevents mixing of blood flow

Question 11

Why do cardiac muscles never get tired?

Answer 11

1. Steady supply of O2 and nutrients through coronary artery.
2. Cardiac muscles have more mitochondria than skeletal muscles to supply enough ATP.

Question 12

What does the Sinoatrial Node do?

Answer 12

The SA node is the most imp. element in the electrical circuit of the heart.
Starts the cardiac cycle by periodically generating action potentials without any external stimulation.
“Pacemaker of the heart”

Question 13

What nerves control the heart beat rate?

Answer 13

Sympathetic nerve + Parasympathetic (vagus) nerves

Question 14

How is a normal heart beat maintained?

Answer 14

Slow continuous discharge from sympathetic nerves.

Question 15

What composes the protection system of the heart?

Answer 15

Adipose tissue
Pericardium
Pericardial fluid
Epicardium

Question 16

What does the pericardial cavity contain and why?

Answer 16

Small amount of serous fluid –> reduce surface tension and lubricate –> cavity facilitates the free movement of the heart

Question 17

What is the total area of blood vessels?

Answer 17

~1000m^2

Question 18

What is the structure of arteries?

Answer 18

Thick and elastic layers
Smooth muscle layer for dilation and construction

Question 19

What is the structure of veins?

Answer 19

Thinner than arteries
Have safety valves
Elastic material

Question 20

What is the structure of capillaries?

Answer 20

Very thin
Endothelial cells
Size: 0.5 micro m

Question 21

How can blood be transported in one way? (upward)

Answer 21

Venous valves: one way valve in vein
Contraction of skeletal muscle

Question 22

What is Angiogenesis?

Answer 22

Formation of new blood vessels from the existing vasculature.

Migration, growth, differentiation of endothelial cells (lined in the inside wall of blood vessels)

Question 23

How many Americans suffer from heart failure?

Answer 23

5.7 million

Question 24

How many annual cases of heart failure are there in the US?

Answer 24

670 000 new cases of heart failure annually

Question 25

How many Americans die due to heart failure each year?

Answer 25

300 000 people

Question 26

Where is the artificial heart placed?

Answer 26

Replacing the right/left ventricles

Question 27

How much does the SynCardia Heart weigh?

Answer 27

160g

Question 28

SynCardia Heart implanted ever since?

Answer 28

2010

Question 29

What is the relationship of exercise and heart?

Answer 29

More exercise –> bigger heart –> bigger pump –> more blood out –> more oxygen to muscles –> more energy