Transport in Animals Key Terms and Processes

Question 1

Describe cardiac muscle

Answer 1

• cardiac cells are connected by intercalated disks which both transmit the force of a contraction and allows the rapids spread of depolarisation from one cell to another (electrical excitation) so all the muscle cells operate as one unit

Question 2

Depolarisation

Answer 2

Myocardium is made up of cardiac muscle fibres, when the muscle fibre is excited through the electrical activity, it is called depolarisation, it starts at the atrium and spreads all over the heart and ends at the apex.

Question 3

Repolarisation

Answer 3

After complete depolarisation, the heart muscle will be relaxed for a while, this is repolarisation

Question 4

Function of the:

Coronary Artery

Answer 4

1st branch of the aorta, provides oxygenated blood to the cardiac muscle

Question 5

Function of the:

Cardiac Muscle

Answer 5

The cells will contain numerous mitochondria (to provide ATP) and myoglobin. Cells arranged in long columns to form a fibre, cells are myogenic

Question 6

Function of the:

Septum

Answer 6

This separates the two sides of the heart, to prevent mixing of oxygenated and deoxygenated blood

Question 7

Function of the:

Tendinous Cord

Answer 7

These insert into the ventricle wall, are v, tough and prevent what they’re attached to from turning inside out

Question 8

Function of the:

Left Ventricle

Answer 8

Blood passes into this chamber before being pumped out through the aorta, blood is under high pressure, so the wall is very thick and muscular

Question 9

Function of the:

Left Atrium

Answer 9

Oxygenated blood from the lungs enter via the pulmonary vein

Question 10

Function of the:

Right Atrium

Answer 10

Deoxygenated blood in the vena cava passes into this chamber, it is under low pressure

Question 11

Function of the:

Right Ventricle

Answer 11

Blood passes into this chamber before being pumped out into the pulmonary artery going to the lung

Question 12

Function of the:

Tricuspid Valve

Answer 12

This thin bit of tissue prevents blood from flowing backwards when the blood underneath it exerts a high pressure causing it to stay shut

Question 13

Function of the:

Semi-Lunar Valve

Answer 13

This thin bit of tissue prevents blood from flowing backwards into the ventricles when they relax in the cardiac cycle

Question 14

Open Circulatory System

Answer 14

• Blood flows freely in body cavity
• Pumped by the heart
• In contact with body cells

Question 15

Closed Circulatory System

Answer 15

• Blood enclosed in blood vessels, no direct contact with body cells

Question 16

Single Circulatory System

Answer 16

• Blood flows through the heart once during each circulation of the body

Question 17

Double Circulatory System

Answer 17

Blood flows through the heart twice for each complete circulation of the body

Question 18

Pulmonary Circulation

Answer 18

Circuit carrying blood to and from the lungs

Question 19

Systematic Circulation

Answer 19

Circuit of blood carrying blood around the body to the tissues

Question 20

Systole

Answer 20

The period of contraction of the heart, especially of the ventricles, during which blood is forced into the aorta and pulmonary arteries

Question 21

Diastole

Answer 21

The period of relaxation of the heart, where the blood passively fills the atria of the heart

Question 22

Bradycardia

Answer 22

• Pattern of electrical activity is normal but slow
• A reduced heart rate could indicate; good aerobic fitness, drugs (tranquilisers), but patient may be at risk of stagnation and blood disease if not investigated into

Question 23

Fibrillation

Answer 23

• Contraction of cardiac muscle is usually coordinated, the ventricle fibrillation. the ventricles contract but it is uncoordinated, this is felt as fluttering, and little blood is pumped.
• Defibrillation may work; the heart is shocked, the heart stops and is restarted, hopefully with a regular, coordinated heartbeat

Question 24

Tachycardia

Answer 24

• An elevated heart rate for no reason, sometimes heart rate is so high, little blood is being pumped round the body
• Treatment can include relaxation therapy or taking beta blockers

Question 25

Ectopic Heartbeats

Answer 25

These heartbeats are small changes in an othewise normal heartbeat, there are two types:
- premature ventricular contractions (PVC)
- premature atrial contractions (PAC)
Causes could include :
- changes in blood, eg low potassium levels
- decrease in blood supply to the heart
- if the heart is enlarged
it can also also be caused by smoking, alcohol use, caffeine, stimulant medicines and some street drugs

Question 26

Cardiac Cycle

Right Side

Answer 26

-deoxygenated blood enters the right atrium of the heart from the upper body and head in the superior vena cava, and from the lower body in the inferior vena cava, at a relatively low pressure
- as the blood flows in, pressure builds up until the atrioventricular valve (tricuspid) opens to let blood pass into the right ventricle
- when both the atrium and ventricle are filled with blood, the atrium contracts, forcing all the blood into the right ventricle, stretching the ventricle walls
- as the right ventricle starts to contract, the tricuspid valve closes, preventing any backflow inbto the atriujm
-the tendinous cords make sure the valves do not utnr inside out due to pressure exerted when the ventricle contracts
- the right ventricle contracts fully and pumps deoxygenated blood through the semilunar valves into the pulmonary artery, which transports it to capillary beds of the ungs
- the semilunar valves prevent the back flow of blood
-

Question 27

The Cardiac Cycle

Left Side

Answer 27

• oxygenated blood from the lungs neters the left atrium from the pulmonary vein
• as pressure in the atrium builds, the bicuspid valve opens between the left atrium and the left ventricle
• the ventricle fills with oxygenated blood
• when both the atrium and ventricle are filled with tblood the atrium contacts to force any additional blood into the ventricle
• the left ventricle then contracts and pumps oxygenated blood through the semi-lunar valves into the aorta and around the body

Question 28

Why is the left side of the heart so much thicker than the right?

Answer 28

The left side is significantly more muscular as the left side has to produce sufficient force to overcome the resistance of the aorta and the arterial systems of the whole body and move the blood under pressure to all the extremities of the body