Module 3 : Exchange surfaces , Transport in animals

Question 1

Tracheoles , Vital capacity , Trachea

Answer 1

tracheae network extends into - dead end tubes - extend tissues - delivering air direct to tissues

maximum air that can be breathed out in one or more breath

• lined with cilia(waft mucus back throat - destroyed hcl ) / goblet cells(secretes mucus- traps pathogens/dust) - non-specific defence

Question 2

SA:V ratio calculations

Answer 2

cube - SA(l x l x 6) - V l^ 3
- cuboid - SA 2(lh + lw + hw)
- cycliner - SA- 2pir^2 + 2pi rh

l ( length ) , w ( width ) , h( height )

Question 3

Outline the mechanism of inspiration and expiration in fish.

Internal/external intercostal muscles

Answer 3

Inspiration - fish open mouth - lower floor of buccal cavity - volume inside increase & pressure decrease - water move high pressure outside out fish to in fish

Expiration - fish raise floor buccal cavity - pressure increase / volume decrease - water goes buccal cavity to over gill cavity - pressure rise - operculum open -

IIM- contract to cause expiration ( exhaling)
-EIM- contract to cause inspiration ( inhaling)

Question 4

Outline the role of the tracheole fluid in gas exchange, Tracheae

Answer 4

insects respire anaerobically - produce lactate in muscles -

Tracheae - internal network of tubes - deliver gas to incests tissues

Question 5

Spiracles, Alveoli, Tidal volume , Residual volume

Answer 5

• gas enters / leaves at the end of tubes
• • large SA- aid diffusion
• thin walls - short diffusion distance
• rich blood supply - maintain conc grad of o2
• volume that is breathed in or out during normal breathing
• The volume of air left in the lungs after forceful maximum expiration

Question 6

Oxygen uptake , Breathing rate:

Answer 6

The volume of oxygen used by someone in given time

Amount of oxygen consumed (dm^3) / time in seconds (s)
L/s

number of breaths per minute ( 1bresth = inhale / exhale )

Number of breaths x 60 s / number of seconds
Bpm

Question 7

Diaphragm , Explain how the countercurrent mechanism of gas exchange helps fish maximise oxygen uptake.

Answer 7

Contracts and relaxes in mechanism of breathings - inhalation / exhalation

Countercurrentflow - oxygenated blood in gills and water moves over them - move in opp directions
- maximises gas exchange -the con grad of O2 is optimal in gill plate

Question 8

Explain how the gills are adapted to their function

Answer 8

• gill filaments - tiny structures - lamellae - increase SA- diffusion
• highly folded - increase SA:V - speed diffusion
• rich blood supply - maintain favourable O2 con grad

Question 9

Mechanisms of Expiration , Mechanism of inspiration

Answer 9

IIM contract
2. Ribs - down - thorax (chest cavity ) volume decreases
3. Diaphragm relaxes - decrease more
4. Greater pressure in lungs - then atms - air moves out lungs

1. EIM contract
2. Ribs - up and put - thorax (chest cavity ) volume increases
3. Diaphragm contracts & flattens - increase more
4. Reduced pressure in lungs - dif pressure of atmospheric / pulmonary - air moves in lungs

Question 10

Bronchi and bronchioles

Answer 10

bronchi - fork bottom trachea - extend airway deeper into lungs - cartilage/muscle similar trachea

• bronchioles - branching airways made of muscle lined epithelial cells - more narrow/deep

Question 11

Explain how a spirometer is set up to measure someones oxygen uptake while exercising

Answer 11

Nose clip are placed on the subject
-mouth piece fitted to the air tank- contains O2 - soda lime removes co2 - prevent respiratory distress
- breathe in/out - lip moves up/down - drawing a trace

Question 12

Explain why the single circulatory system would not be suited to mammals

Answer 12

As the blood pressure would be too low ( pressure is lost during each capillary network)

Question 13

Explain why insects circulatory systems can be less efficient at oxygen transport than mammalian counterparts

Answer 13

As they got a very efficient gas exchange system that directly delivers oxygen to tissues

Question 14

Outline the pathway of the blood in the double circulatory system of a mammal ( refer to heart chambers & blood vessels)

Answer 14

Deoxygenated blood leaves the right ventricle via the pulmonary artery and enters lungs
Oxygenated blood - return to heart via pulmonary vein in left atrium
Oxygenated blood leaves via left ventricle to body
Deoxygenated blood returns to right atrium via vena cava

Question 15

Outline the pathway the blood takes in a single circulatory system of fish …

Answer 15

blood flows from heart via ventricle to gills - it’s oxygenated in capillary network
- goes to body capillaries - it’s deoxygenated due to respiration & returns to heart

Question 16

Open / Closed circulatory system

Double circulatory system

Answer 16

• blood does not stay in the blood vessel (insects)
• blood stays in the vessels

has 2 routes - blood returns to the heart - after each capillary - network to restore pressure

Question 17

Single circulatory system

Describe and explain 4 ways in which the artery is adapted to its function

Answer 17

Has 1 route round per cycle

Thick muscular walls- to contract in vasoconstriction/dilation
Elastic walls- to withstand and control blood pressure Smooth endothelium- to reduce friction in the blood Narrow lumen- to keep pressure high

Question 18

Describe and explain 4 ways in which the vein is adapted to its function

Describe and explain 4 ways in which the capillary is adapted to its function

Answer 18

Elastic walls- thinner than arteries as blood pressure lower Muscular walls- to maintain pressure (not as thick as arteries as blood pressure is not as high)
Smooth endothelium to reduce friction
Valves to prevent backflow of blood

Smooth endothelium to reduce friction Fenestrations to allow only small molecules out during tissue fluid formation
Extremely narrow lumen to force red blood cells through 1 cell at a time and maximise diffusion time
1 cell thick walls to maximise diffusion into tissues

Question 19

Explain how tissue fluid is produced at the arterial end of the capillary

Explain how tissue fluid returns to the capillary at the venular end of the capillary

Answer 19

Hydrostatic pressure is greater than oncotic pressure at the arterial end
- There is a net outlflow out the capillary- small molecules pass out through the fenestrations
- proteins remain in the tissue fluid

Hydrostatic pressure is less than oncotic pressure at the venular end
- There is a net inflow to the capillary- small molecules pass in through the fenestrations
Lymphatic vessels pick up tissue fluid that does not flow back into capillary

Question 20

Cardiac cycle

Answer 20

diastole - the heart ( atria/ventricles ) relax- blood flows into atria from pulmonary vein and vena cava -semi-lunar valve closed , atrioventricular valve open

2- Atrial systole - atria contract - pushing blood into ventricle- they relax - semi-lunar valves closed - atrioventricular valves open
- blood pumped from atria to ventricles

3- ventricular systole - ventricles contract forcing blood out aorta & pulmonary artery
- semilunar valves open - atrioventricular valves closed

Question 21

Electrical control of the heart

Answer 21

1. Electrical wave of excitation ( depolarisation) spreads out from the SAN causing the atria to contract
2. Wave enters a second group of cells called AVN ( atrioventricular node ) - lies between atria
3. AVN conveys wave between the ventricles along specialised muscle ‘ PURKYNE tissue ‘ - makes bundle of HIS
4. Bundle of HIS - conduct wave through septum to base of ventricles - where bundle branches into purkyne tissue
5. Wave of excitation released from purkyne tissue - ventricles contracting quickly from bottom upwards

Question 22

The Four ECG’s

Answer 22

Tachycardia - when the heart beats too fast ( over 100bpm)
- bradycardia - heart rate is too low - below 60bpm ( in athletes cab be normal
- ectopic heart beat - early heartbeat followed by a pause - common - no treatment unless severe
- fibrilation - irregular heartbeat will disrupt the rhythm , can be very dangerous if not treated

Question 23

Describe the events at each stage of the ECG

Answer 23

P- wave - caused by depolarisation of atria
- QRS complex - depolarisation of ventricles in ventricular systole
- T-wave - repolarisation of ventricles
- U wave- could be purkyne fibres repolarising

Question 24

Explain why the haemoglobin curve is Sigmoid ‘S’ shaped.

Answer 24

At low partial pressures of oxygen, haemoglobin does not easily bind oxygen forming oxyhemoglobin
- After first oxygen binds there is a conformational change in the haemoglobin so it binds more easily
It levels out a higher concentration of oxygen as the haemoglobin is full and can only carry 4 molecules of 02.

Question 25

Explain why the fetal haemoglobin needs to have a higher affinity than the adult haemglobin

Answer 25

Fetal haemoglobin has a stronger affinity for oxygen than adult haemoglobin- it dissociates much less easily too
This is because it is at a lower partial pressure of oxygen, and needs to get oxygen from the mother

Question 26

Why is it important fetal haemoglobin is replaced by adult haemoglobin after birth?

Answer 26

It is advantageous to the baby that HbA replaces HbF because it dissociates its oxygen in areas less oxygen
Increased dissociation when the baby is born is good because it means the oxygen will be deposited to tissues needed by the baby now that it is moving and using more energy – used in respiration

Question 27

Describe how carbon dioxide is transported in the blood?

Which enzyme catalyses carbonic acid production?

Describe what happens to the ions when carbonic acid dissociates?

Answer 27

Carbon dioxide forms with water to produce carbonic acid

C02 + H20 -> Carbonic acid
- Carbonic anhydrase

H+ ions will bind to haemoglobin to form haemoglobninic acid
HCO3- ions leave the RBC and enter plasma