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Transport in animals Flashcards

1
Q

State the formula for the surface area of a sphere

A

A=4πr^2

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2
Q

State the formula for the volume of a sphere

A

V=4/3xπxr^3

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3
Q

State the formula for the volume of a cylinder

A

V=πr2h

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4
Q

State the formula for the surface area of a cylinder

A

A=2πrh+2πr^2

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5
Q

What is an open circulatory system?

A

Fluid is not contained within vessels, opens into body cavity where fluid bathes cells directly

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6
Q

What is a closed circulatory system?

A

Fluid is enclosed in vessels

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7
Q

What is a single circulatory system?

A

Blood passes through the heart once and does not split into two pathways

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8
Q

What is a double circulatory system?

A

Blood passes through the heart twice and splits into two directions/ pathways

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9
Q

What are 4 features of a good transport system?

A
  1. A fluid or medium to carry nutrients and remove waste products
  2. A pump to create pressure that will push fluid around
  3. Exchange surfaces enables surfaces to enter and leave the blood
  4. Tubes or vessels to carry the blood by mass flow
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10
Q

Describe disadvantages of a single circulatory system

A
  • BP drops as it passes through capillaries
  • Low BP= flow is slow
  • Rate of oxygen delivery and carbon dioxide removal is limited
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11
Q

Why is a single circulatory system ideal for fish?

A
  • their heart pumps poorly oxygenated blood to their gills where oxygen is absorbed from the water
  • Lesser metabolic needs, offers energy efficiency
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12
Q

Describe how a double circulatory system is suitable for mammals

A
  • BP must be controlled so it doesn’t damage capillaries in the lungs
  • Systemic circulation can be at higher pressure than pulmonary pressure so lung capillaries wont be damaged, delivery to tissues is quicker
  • Distributes heat and is more active which satisfies mammals’ high demands
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13
Q

State the differences in the relative size of lumen to the wall in an artery, vein and capillary

A

Artery= small
Vein= large
Capillary= smallest (width of RBC)

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14
Q

Describe relative thickness of the walls in; artery, vein, capillary

A

Artery= thickest
Vein= thin
Capillary= very thin, one cell thick, flat endothelial cells

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15
Q

What tunica contains smooth endothelium to aid flow by reducing friction?

A

Tunica interna

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16
Q

Describe the tunica media for arteries, veins and capillaries

A

Artery= Thick, smooth muscle and elastic flow

Vein= Thinner, less smooth muscle and elastic fibres

Capillaries= None, only endothelial cells

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17
Q

Describe the tunica externa for arteries, veins and capillaries

A

Artery= thick, collagen for structural support with some elastic fibres

Vein= Can be thick, mostly collagen

Capillary= Only endothelial cells

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18
Q

What happens to the rate of flow and pressure as blood flows through vessels?

A
  • pressure drops away from the heart
  • Cross sectional area increases from artery to arteriole to capillary, lowering pressure, slowing the rate of flow
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19
Q

What adaptations do veins have?

A
  • Valves to prevent backflow in low pressure
  • blood flows in one direction
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20
Q

What is oncotic pressure?

A
  • Pressure exerted by larger proteins in the plasma ‘pulls’ water into vessel
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21
Q

What is hydrostatic pressure?

A
  • Pressure of the blood as it surges through the arterioles into the capillaries under the influence of the heart
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22
Q

Briefly describe how tissue fluid is formed

A
  1. HS pressure is higher (in blood than tissue fluid) at arterial end, higher oncotic pressure at venous end
  2. Plasma pushed out through fenestrations and is now tissue fluid
  3. HS pressure in the blood decreases as fluid is lost as it flows through capillary
  4. Reaches a point where HS and OP is higher in tissues than in the blood, fluid moves back into capillary by osmosis
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23
Q

What is the purpose of tissue fluid?

A
  • facilitates substance exchange between cells and the blood
24
Q

How is lymph formed?

A
  1. Filtration from plasma exceeds reabsorption, net formation of tissue fluid
  2. Increases tissue fluid HS pressure forcing fluid (10%) into lymph vessels forming lymph
  3. This prevents accumulation of excess tissue fluid or oedema
25
Describe the composition of lymph
Has less glucose and oxygen but more CO2 than tissue fluid Higher in fatty acids near the digestive system
26
Describe the pathway of blood through both sides of the heart
1. Blood enters left atrium via pulmonary vein 2. Flows into left ventricle via the atrioventricular valve 3. blood is pumped through to the right ventricle 4. Blood flows through the tricuspid valve into the right atrium and flows through the pulmonary artery through semilunar valves
27
What happens during atrial systole (brief)
1. Both left and right atria contract together 2. Pressure increases, blood pushed into ventricles. 3. Once ventricles are full they begin to contract 4. increase in pressure closes the AV valves 5. Short period where all valves are shut
28
What happens in ventricular systole? (brief)
1. pressure rises 2. SL valves open 3. blood is pushed through into arteries 4. V walls relax 5. arterial pressure closes SL valves shut
29
What happens in diastole? (brief)
1. Both atria and ventricles are relaxed 2. Blood flows into atria 3. blood continues through open AV valves and into ventricles
30
How is the 'lub' sound made?
- AV valves closing as the ventricles start to contract
31
How is the 'dub' sound made?
- SL valves closing as the ventricles start to relax
32
Why is coordinated contraction of the chambers important?
- allows maximum flow of blood to meet demands
33
What does the sino-atrial node do?
- Sends out a wave of excitation through the walls of both atria and causes atrial systole - blood is forced into ventricles
34
What does the atrioventricular node do?
- Delay wave until atria are finished contracting and ventricles are full - impulse cannot pass directly into ventricles due to a band of non-conducting tissue that separates atria, passage is slowed - Sends wave down septum via purkyne fibres to apex
35
What do purkyne fibres do?
- Carry the wave of excitation down the septum to the apex - wave spreads up from apex through ventircle walls, causing ventricular systole - blood pushed into arteries - diastole
36
What is the purpose of an ECG?
- measures electrical excitation through the heart - measures electircal differences in the skin caused by the electrical activity of the heart
37
What does the P wave represent?
- excitation of the atria
38
Describe what the QRS wave represents
- excitation of ventricles
39
What is the T wave?
- diastole, ventricles relax
40
What is Tachycardia and Bradycardia?
Tachycardia= heart beats too fast, normal during exercise, may need medication or surgery if abnormal Bradycardia= Slow heart beat, normal in fit people (athletes), may need pacemaker in severe cases
41
What is an Ectopic heartbeat and fibrillation?
Ectopic= extra heart beat, common, one a day, could be serious if more frequent Fibrillation= rapid contraction, impulses not always passed on
42
Define myogenic
Heart will beat without any external stimulus
43
Describe the structure of haemoglobin
- 4 subunits, each subunit has a polypeptide chain and a haem group - haem group contains a single iron atom Fe2+
44
What is affinity?
- Attraction
45
Why is oxygen measured as a partial pressure?
- Pressure exerted by a given gas in a mixture - better than using concentration and concentration wont change but pressure will
46
What happens at low PO2 (brief)?
- Haemoglobin doesn't take up oxygen due to haem groups being in the centre of the hb molecule - Difficult for O2 to reach haem group and associate - difficulty combining= low saturation level of haemoglobin
47
What happens when PO2 begins to rise?
- Diffusion gradient into Hb molecules increase - One O2 molecule diffuses into haem and associates - causes slight change in conformational shape of Hb molecule
48
What does conformation change of shape cause?
- O2 molecules to diffuse into the Hb molecule and associate with the other haem groups easily - accounts for steepness of curve
49
How is foetal haemoglobin different to adult haemoglobin?
- Foetal Hb has a greater affinity for oxygen, the placenta has low oxygen so the foetal Hb is able to load more oxygen - low PO2 mothers blood is only slightly higher, low concentration gradient across placenta - picks up oxygen and holds on to it, oxygen diffuses out of mother's blood
50
How much CO2 is dissolved directly in the plasma?
5%
51
How much Co2 combines with haemoglobin to form carbaminohaemoglobin?
10%
52
How much CO2 is converted to HCO3- ions in the cytoplasm?
75-85%
53
Explain the fate of CO2 in RBC's briefly (6)
1. CO2 diffuses in, reacts with water and forms carbonic acid 2. Catalysed by carbonic anhydrase 3. Carbonic acid dissociates to form H+ ions and HCO3- ions 4. HCO3- ions diffuse out into blood plasma, to counter the loss of negative ions chloride moves into the RBC cytoplasm (chloride shift) 5. H+ ions formed are taken up by Hb----> haemoglobinic acid, prevents drop of ph, acts as buffer 6. when combined with H+ ions it causes oxyhaemoglobin to release its oxygen ---> respiring tissues
54
What is a chloride shift?
Were chloride ions diffuse into the RBC's cytoplasm to counter the loss of negative ions.
55
What is the Bohr effect?
Results in oxygen being readily released when more CO2 is produced from respiration
56
What is the Bohr shift?
1. the movement of the oxygen dissociation curve to the right of normal due to increased levels of carbon dioxide
57
How does increased PCO2 affect haemoglobin?
When the partial pressure of carbon dioxide in the blood is high, haemoglobin's affinity for oxygen is reduced.

Biology (13 decks)

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