3.4.1: Mass transport in animals

Question 1

Where are the coronary arteries?

Answer 1

• Branch off from aorta
• Supply. cardiac muscle with oxygenated blood

Question 2

Why is the left ventricle thicker than the right ventricle?

Answer 2

Right ventricle pumps blood through pulmonary arteries only and the left ventricle is pumping blood through a larger number of capillaries around the whole body

Question 3

Describe heart structure

Answer 3

• Deoxygenated blood returns from body in the vena cava and enters the right atrium
• Blood passes through atrio-ventricular valve in the right ventricle and out by the semi-lunar valve into the pulmonary artery.
• Blood passes through lungs and oxygenated blood returns into the left atrium by the pulmonary vein
• Blood passes through atrio-venticular valve into the left ventricle and through the semi-lunar valve into the aorta

Question 4

What is systole?

Answer 4

Contraction of heart muscle

Question 5

What is diastole?

Answer 5

Heart muscle relaxed

Question 6

Cardiac cycle:

Answer 6

1) Blood enters atrium, blood volume increases pressure in atrium. Pressure in atrium grater then in ventricle. AV valve opens.
2) Atrial systole - atrium muscles contract further increasing pressure, blood forced into ventricle from atrium.
3) Blood enters ventricles increasing pressure. Pressure in ventricle greater than atria. AV valve closes.
4) Ventricular systole - ventricle muscles contract, increasing pressure until its greater than in artery. SL valve opens. Blood enters artery
5) Ventricular diastole - Pressure in ventricle is less than artery. SL valve closes. Blood enters atrium

Question 7

Equation for cardiac output

Answer 7

cardiac output = stroke volume x heart rate

Question 8

Why do mammals require a double circulatory system?

Answer 8

• Manage the pressure of blood flow
• Blood flows through lungs at lower pressure which prevents damages to capillaries in alveoli and reduce speed of blood flow so more gas exchange occurs
• Blood flows through body at high pressure so blood reaches all respiring cells

Question 9

What is the name for the blood vessels associated with the kidneys?

Answer 9

Renal

Question 10

Artery muscle layer?

Answer 10

Thicker than veins so can constriction and dilation can occur to control volume of blood

Question 11

Artery elastic layer

Answer 11

Thicker than veins to maintain blood pressure. Walls can stretch and recoil in response to heart beat

Question 12

Artery wall thickness

Answer 12

Thicker walls than veins to prevent vessels from bursting from high pressure

Question 13

What is the function of an artery? (3)

Answer 13

• transports blood from heart to organ
• Blood under high pressure
• thick wall to withstand pressure

Question 14

Arteriole

Answer 14

Smaller than arteries and connects them to capillaries

Question 15

Muscle layer arteriole

Answer 15

Thicker than arteries to help restrict blood flow into capillaries

Question 16

Arteriole elastic layer

Answer 16

Thinner than arteries as blood pressure is lower

Question 16

Arteriole wall thickness

Answer 16

Thinner as lower pressure

Question 17

Capillary function

Answer 17

Exchange of materials between blood and tissues

Question 18

Capillary muscle layer

Answer 18

No muscle layer

Question 19

Vein elastic layer

Answer 19

• Thin
• Low pressure walls don’t need to stretch and recoil

Question 19

Capillary elastic layer

Answer 19

No elastic layer

Question 20

Vein function (4)

Answer 20

• Carries blood back to heart from tissues
• Valves - blood flows in one direction
• Low blood pressure
• Blood moves along by squeezing of muscles

Question 21

Vein muscle layer

Answer 21

Thin so can’t control blood flow

Question 22

Formula for saturation

Answer 22

(oxygenated haemoglobin / maximum saturation) x 100

Question 23

Why is the oxygen dissociation curve a sigmoid shape?

Answer 23

First O2 molecule alters the tertiary structure of haemoglobin. This exposes the second and third O2 binding sites which makes it easier for the second and third O2 molecules to bind and load

Question 24

What is the Bohr shift?

Answer 24

At higher partial pressure of CO2 haemoglobin affinity for oxygen is even lower. If partial pressure of CO2 increases the saturation of haemoglobin decreases. This causes the oxygen dissociation curve to shift to the right.

Question 25

Why does haemoglobin have a lower affinity to O2 at higher levels of CO2?

Answer 25

When CO2 dissolves in the blood it makes the blood more acidic, lowering the pH. Haemoglobin is a protein so this alters the terry structure.

Question 26

Describe haemoglobin when there is a lower partial pressure of o2?

Answer 26

- Dissociation curve shifts to the left - Haemoglobin has a higher affinity for O2 - Become fully saturated at a lower partial pressure of O2 - Rapidly unloaded when haemoglobin passes through tissues

Question 27

Describe how tissue fluid is formed and how it's returned to the circulatory system.

Answer 27

Formation: - In arteriole end the blood has higher hydrostatic pressure - Forces fluid out - Large proteins remain in capillary Return - Lower water potential in capillary - Due to plasma proteins - Water enters capillary - By osmosis - Excess water is removed from tissues by lymph vessels

Question 28

What is haemoglobin?

Answer 28

Quaternary protein that transports oxygen

Question 29

Structure and function of cardiac muscle

Answer 29

- Thick muscular layer - Myogenic so can contract ad relax without nervous or hormonal stimulation - Never fatigues as long as its supplied with oxygen

Question 30

What happens if coronary arteries becomes blocked?

Answer 30

Cardiac muscle won't receive oxygen, so can't respire so cells will die results in a myocardial infarction.

Question 31

Wall thickness of capillaries

Answer 31

One cell thick for short diffusion distance of exchanging material between blood and cells.

Question 32

Wall thickness of veins

Answer 32

Thin as pressure is low so less risk of bursting

Question 33

What is tissue fluid?

Answer 33

Fluid containing water, glucose, amino acids, fatty acids, ions and oxygen around the tissues.