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AS Biology F211 Spec > Transport in animals > Flashcards

Transport in animals Flashcards

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1
Q

Why do multicellular animals need a transport system?

A
  • size: diffusion alone will not allow oxygen and nutrients to reach cells deep in body - will be used up at surface
  • SA:Vol: Surface area isn’t large enough to supply everything needed by internal cells (as animals grow, they need more structural support tissue, increasing their volume)
  • Level of activity: active animals (including staying warm) need to respire more, so their cells need a good supply of oxygen and nutrients
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2
Q

Single circulatory system

A

In fish. Blood flows: heart -> gills -> body -> heart.

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3
Q

Double circulatory system

A

In mammals. 2 circuits: pulmonary circulation and systemic circulation. Pulmonary oxygenates blood; systemic carries oxygen and nutrients to tissues. Blood flows: heart -> lungs -> heart -> body -> heart. Blood flows through heart twice for each circulation of the body

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4
Q

Open circulatory system

A

In insects. Blood is not always contained in vessels - bathes cells directly. Blood only transports nutrients as gases have a separate transport system. Muscular bag keeps blood circulating - pumps by peristalsis, enters through pores called ostia. Movement of muscles may help circulate blood

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5
Q

Closed circulatory system

A

In larger animals, e.g. fish. Blood stays in vessels all the time, never in direct contact with tissues. Tissue fluid bathes tissues. Allows blood to be pumped at a higher pressure so nutrients and gases can be delivered more quickly, and wastes removed. Must be exchange surfaces at gills/lungs.

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6
Q

Structure of heart (external)

A
  • Aorta in an arch
  • Pulmonary artery goes through aortic arch
  • Vena cava
  • Atria at top (right on the left - usually)
  • Ventricles at bottom (right on the left - usually)
  • Coronary arteries over surface
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7
Q

Structure of heart (internal)

A
  • Right atrium leads to right ventricle through right atrioventricular (tricuspid) valve
  • Right ventricle leads to pulmonary artery through semilunar valve
  • Left atrium leads to left ventricle through left atrioventricular (bicuspid) valve
  • Left ventricle leads to aorta through semilunar valve.
  • Septum divides ventricles
  • Tendons stop valves from turning inside out
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8
Q

Thickness of atria walls

A

Very thin muscular wall. Only moving blood from one chamber to the next, so don’t need to create much pressure.

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9
Q

Thickness of ventricle walls

A

Thicker than atria walls, as pumping blood to body, so need to create more pressure. Right ventricle has thinner walls than left ventricle, as blood only going to lungs (not far and don’t want to damage capillaries). Left ventricle has very thick walls, as is pumping blood around the body. Must create enough pressure to overcome resistance of systemic circulation.

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10
Q

Cardiac cycle: sequence of events in one heart beat

A
  • Filling phase: diastole. Atria and ventricles are relaxing, blood flows into the heart
  • Atrial contraction: atrial systole. Atria contract together, helping to push blood into the ventricles, ensuring they are full of blood.
  • Ventricular contraction: ventricular systole. Ventricle walls contract from apex upwards. Increases pressure, pushing blood out of the heart.
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11
Q

Cardiac cycle: the valves

A
  • Filling phase: atrioventricular valves open, allowing blood to flow into ventricles
  • Atrial contraction: atrioventricular valves are open, so blood can flow into ventricles
  • Ventricle contraction: at start, atrioventricular valves snap closed (‘lub’ sound in heart beat), so blood can’t pass back into atria. Semilunar valves open at beginning, so blood can flow into the arteries. Close at end as pressure in ventricles fall (‘dub’ sound in heart beat).
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12
Q

Heart muscle

A

Cardiac muscle. Myogenic - can initiate own contraction. Never tires

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13
Q

Sinoatrial node

A

Heart’s pacemaker. Small patch of tissue that sends out waves of electrical excitation at regular intervals

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14
Q

Purkyne tissue

A

Specially adapted muscle fibres that conduct the wave of excitation from the AVN down the septum to the ventricles

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15
Q

Co-ordination of the cardiac cycle

A
  • Sinoatrial node (SAN) initiates a wave of excitation
  • Wave spreads across atria, causing them to contract
  • Band of tissue stops wave spreading to ventricles
  • Wave slowed down by atrioventricular node (AVN, at top of inter-ventricular septum) so ventricles can fill properly
  • Wave carried down septum through purkyne tissue
  • Wave spreads out over ventricle walls, causing them to contract from apex
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16
Q

Shape of electrocardiograms (ECG)

A
  • Starts with a small bump, wave P - atrial contraction
  • Then a dip, Q
  • Then a big bump, R, of ventricles contracting
  • Then a smaller bump, T, of ventricles repolarising
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17
Q

ECG heart attack

A

Elevated ST section (part after ventricle contraction)

18
Q

ECG atrial fibrillation

A

Small, unclear P wave (start bit)

19
Q

ECG ventricular hypertrophy

A

Deep S wave (just after ventricle contraction). Increased muscle thickness

20
Q

Increase of muscle thickness in heart is called…

A

Ventricular hypertrophy

21
Q

Structure of arteries

A

Carrying blood at high pressure - must withstand

  • Lumen small to maintain pressure
  • Wall is thick, contains collagen to withstand pressure
  • Elastic tissue in wall to allow artery to stretch and recoil (maintains high pressure when heart relaxes)
  • Smooth muscle in wall that can constrict the arteries (used to limit blood flow in arterioles)
  • Endothelium is folded, unfolds when artery stretches
22
Q

Structure of veins

A

Carry blood at low pressure - walls don’t have to be thick

  • Lumen is large to ease flow of blood
  • Only thin layers of collagen, smooth muscle and elastic tissue: don’t need to stretch and recoil or constrict
  • Contain valves to prevent blood flow in opposite direction.
  • Thin walls means veins can be flattened by action of skeletal muscles, creating pressure to move blood along
23
Q

Structure of capillaries

A

Allow exchange of material between blood and cells

  • Walls are a single layer of flattened endothelial cells to reduce diffusion distance
  • Narrow lumen so red blood cells are squeezed as they pass along the capillaries: reduces diffusion distance as pressed up close.
24
Q

Blood, tissue fluid and lymph: cells

A
  • Blood: erythrocytes, leukocytes, platelets
  • Tissue fluid: some phagocytic white blood cells
  • Lymph: lymphocytes
25
Q

Blood, tissue fluid and lymph: proteins

A
  • Blood: hormones and plasma proteins
  • Tissue fluid: some hormones, proteins secreted by body cells
  • Lymph: some proteins
26
Q

Blood, tissue fluid and lymph: fats

A
  • Blood: some transported as lipoproteins
  • Tissue fluid: none
  • Lymph: more than in blood (absorbed from lacteals in intestine)
27
Q

Blood, tissue fluid and lymph: glucose

A
  • Blood: 80-120mg/100cm^3
  • Tissue fluid: Less (absorbed by body cells)
  • Lymph: Less
28
Q

Blood, tissue fluid and lymph: amino acids

A
  • Blood: more
  • Tissue fluid: less (absorbed by body cells)
  • Lymph: less
29
Q

Blood, tissue fluid and lymph: oxygen

A
  • Blood: more
  • Tissue fluid: Less (absorbed by body cells)
  • Lymph: less
30
Q

Blood, tissue fluid and lymph: carbon dioxide

A
  • Blood: little
  • Tissue fluid: more (released by body cells)
  • Lymph: more
31
Q

Formation of tissue fluid

A
  • At arterial end, blood under high hydrostatic pressure (due to heart)
  • Pushes blood into tissues through gaps in capillary wall
  • Only plasma with dissolved nutrients can leave: cells and proteins are too big
  • Fluid that leaves is tissue fluid: bathes cells, exchanging gases and mineral ions
32
Q

Fluid returning to blood

A
  • At venous end, tissue fluid has a less negative water potential than the blood (blood contains proteins and cells)
  • Moves back into the blood under osmotic pressure
  • Blood has lost hydrostatic pressure, so moves back in
  • Tissue fluid has hydrostatic pressure, pushing it back into the capillaries
33
Q

Formation of lymph

A

Tissue fluid is drained by lymphatic system (rejoins blood in chest cavity). Contains same stuff as tissue fluid, but after exchange with cells - so less oxygen and more carbon dioxide. More fat (absorbed from intestine). Contains lymphocytes, produced in lymph nodes to destroy bacteria/foreign material

34
Q

Haemoglobin - carrying oxygen

A
  • In erythrocytes
  • Becomes oxyhaemoglobin
  • Can carry up to 4 oxygen molecules (on haem groups - Fe2+)
35
Q

Haemoglobin - dissociation curve

A

-takes up oxygen in an S-shaped curve
-low affinity at low pO2, as haem group in middle of molecule and hard to reach
-once has one oxygen has diffused in, molecule changes shape, making it easier for the 2nd and 3rd oxygen to get in
-difficult for 4th oxygen to associate, so curve tails off at high pO2.
This means haemoglobin will dissociate with oxygen readily in body tissues, but will associate with oxygen in lungs

36
Q

3 ways of transporting carbon dioxide

A
  • Dissolved in plasma (5%)
  • Combined with haemoglobin - carbaminohaemoglobin (10%)
  • As hydrogencarbonate ions in plasma (85%)
37
Q

Forming hydrogencarbonate ions

A
  • Enzyme CARBONIC ANHYDRASE catalyses formation of carbonic acid: CO2 + H2O -> H2CO3
  • Carbonic acid dissociates to H+ and HCO3-
  • Hydrogencarbonate ions diffuse out of red blood cells
  • Red blood cells have a lot of H+ ions: Cl- ions diffuse in - chloride shift - to maintain charge. Also, some H+ forms haemoglobinic acid by combining with haemoglobin (acting as a buffer)
38
Q

Bohr effect

A
  • when carbon dioxide is present, H+ ions are formed from the dissociation of carbonic acid
  • H+ ions compete for space on haemoglobin molecule, making oxyhaemoglobin release more oxygen.
  • dissociation curve shifts to right and downwards
39
Q

Fetal haemoglobin

A

Higher affinity than adult haemoglobin, takes up oxygen at a lower partial pressure (e.g. in the placenta), as has to pick up oxygen from an environment that makes adult haemoglobin dissociate with oxygen. Fetal haemoglobin absorbs oxygen from fluid in mother’s blood, making maternal haemoglobin release more oxygen.

40
Q

Benefits of Bohr shift

A
  • actively respiring tissue needs more oxygen for aerobic respiration, and produce more CO2
  • haemoglobin involved in transport of CO2, so less haemoglobin available to combine with oxygen
  • more oxygen is released

AS Biology F211 Spec (6 decks)

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