Transport In Animals

Question 1

Diastole

Answer 1

Pressure is low, blood enters the atria then pressure increases as left atrium fills with blood pushing open the atrioventricular valves. Blood flows into the ventricles

Question 1

Atrial systole

Answer 1

Pressure increases due to atrial contraction, blood forced into left ventricle

Question 2

Cardiac output

Answer 2

Stroke volume x heart rate

Question 3

Ventricle systole

Answer 3

Further increase in pressure as left ventricle contracts.
Increase pressure of left ventricle causes atrioventricular valve to close
Higher pressure in ventricle forces blood into aorta

Question 4

Explain how the different affinities of maternal and fetal haemoglobin enable transfer of oxygen from the maternal circulation to the fetus.

Answer 4

Fetal haemoglobin has a higher affinity for oxygen. Low pO2 in placenta so oxygen dissociates from materal haemoglobin in placenta
Oxygen diffuses from maternal to fetal blood
Increases saturation of fetal haemoglobin at lower pO2

Question 5

Structure of aeries to their function

Answer 5

Thick, muscular walls to handle high pressure without tearing.
Elastic tissue allows recoil to prevent pressure surges
Narrow lumen to maintain pressure

Question 6

Structure of veins to their function

Answer 6

Thin walls due to lower pressure. Require valves to ensure blood doesn’t flow backwards.
Have less muscular and elastic tissue as they don’t have to control blood flow

Question 7

Structure of capillaries to their function

Answer 7

Walls only one cell thick: short diffusion pathway
Very Narrow: so can permeate tissues and red blood cells can lie flat against the wall, effectively delivering oxygen to tissues
Numerous and nightly branches: providing a large surface area

Question 8

What does myogenic mean?

Answer 8

The hearts contraction is initiated from within the muscle itself, rather than by nerve impulses

Question 9

Artérioles and veinules to their functions

Answer 9

Branch off arteries and viens in order to feed blood into capillaries
Smaller than arteries and veins so that the change in pressure is more gradual as blood passes through increasingly small vessels

Question 10

What is tissue fluid?

Answer 10

A watery substance containing glucose, amino acids , oxygen and other nutrients. It supplies these to the cells while also removing any waste materials

Question 11

What types of pressure influence formation of tissue fluid?

Answer 11

Hydrostatic pressure= higher at arterial end of capillary than venous end
Oncotic pressure= changing water potential of the capillaries as water moves out, induced by proteins in the plasma

Question 12

Explain how the heart contracts?

Answer 12

• SAN initiates and spreads impulse across the atria, so they contract
• AVN receives, delays, and then conveys the impulse down the bundle of His
  -Impulse travels into the purkyne fibres which branch across the ventricles, so they contract from the bottom up

Question 13

What is an electrocardiogram (ECG)?

Answer 13

A graph showing the amount of electrical activity in the heart during the cardiac cycle

Question 14

Tachycardia

Answer 14

Fast heartbeat (over 100bpm)

Question 15

Bradycardia

Answer 15

Slow heartbeat (under 60bpm)

Question 16

Fibrillation

Answer 16

Irregular, fast heartbeat

Question 17

Ectopic

Answer 17

Early or extra heartbeats

Question 18

Describe the role of haemoglobin

Answer 18

Present in red blood cells. Oxygen molecules bind to the harem groups and are carried around the body, then released where they are needed in respiring tissues

Question 19

How does partial pressure of oxygen affect oxygen-haemoglobin binding?

Answer 19

As partial pressure of oxygen increases, the affinity of haemoglobin for oxygen also increases, so oxygen binds tightly to haemoglobin. When partial pressure is low oxygen is released from haemoglobin

Question 20

What do oxyhemoglobin dissociation curves show?

Answer 20

Saturation of haemoglobin with oxygen (in %), plotted against partial pressure of oxygen (in kPa). Curves further to the left show the haemoglobin has higher affinity for oxygen

Question 21

Describe Bohr effect

Answer 21

As partial pressure of carbon dioxide increases, the conditions become acidic causing haemoglobin to change shape. The affinity of haemoglobin for oxygen therefore decreases, so oxygen is released for haemoglobin

Question 22

Explain the role of carbonic anhydride the Bohr effect?

Answer 22

-carbonic anhydrase is present in red blood cells
-converts co2 to carbonic acid, which dissociates to produce H+ ions
- these combine with the haemoglobin to form haemoglobinic acid
- encourages oxygen to dissociate form haemoglobin

Question 23

Chloride shift

Answer 23

The intake of the chloride ions across a red blood cell membrane.
This repolarises the after bicarbonate ions have diffused out.

Question 24

How does fetal haemoglobin differ from adult haemoglobin?

Answer 24

The partial pressure of oxygen is low low by the time it reaches the fetus, therefore fetal haemoglobin has a higher affinity for oxygen and adult. Allows both mothers and Charles oxygen needs to be met.