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Transport in Animals Flashcards

1
Q

What are the features of a good transport system, and why does it have them?

A

A fluid or medium, to carry nutrients, oxygen and waste around the body
A pump to create pressure that will push the fluid around
Exchange surfaces to enable substances to enter and leave the blood where necessary
Tubes or vessels to carry blood via mass flow

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2
Q

What is an open circulatory system?

A

Not contained in vessels, open into body cavity, where fluid bathes the cells directly)

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3
Q

What is a closed circulatory system?

A

Fluid contained within vessels

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4
Q

What is a single circulatory system?

A

Blood passes through the heart once in each circuit

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5
Q

What is a double circulatory system?

A

Blood passes through the heart twice in each circuit

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6
Q

What circulatory system does a human have?

A

Double, closed.

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7
Q

What circulatory system do most insects have?

A

Single, open

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8
Q

What are the advantages and disadvantages of a single circulatory system?

A

-Blood pressure drops as passes through capillaries in gills
-Low blood pressure as flows to body, means its slow
-Rate of oxygen delivery/CO2 delivery is minimal
-Sufficient for organisms that have it as generally smaller

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9
Q

What circulatory system do fish have?

A

Single, closed

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10
Q

What are the advantages and disadvantages of a double circulatory system?

A

-Blood pressure must be controlled so no damage made to capillaries
-Heart pumps blood again after lungs under higher pressure and flows faster for faster delivery
-Systematic circulation at higher pressure than pulmonary, so lung capillaries undamaged but faster tissue delivery
-Mammals have more demand for oxygen as larger and need energy and are more active, need to distribute heat to maintain temperature

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11
Q

What are the features of an artery?

A

Relative size of lumen: Small
Relative thickness of wall: thickest
Tunica Interna: Smooth endothelium to aid flow
Tunica Media: Thick, smooth muscle and elastic fibres
Tunica Externa: Thick, collagen with some elastic fibres
Pressure: Highest

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12
Q

What are the features of a vein?

A

Relative size of lumen: Large
Relative thickness of wall: Thin
Tunica Interna: Smooth endothelium to aid flow
Tunica Media: Thinner, less smooth, elastic fibres
Tunica Externa: Can be thick, mostly collagen
Pressure: Low

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13
Q

What are the features of a capillary?

A

Relative size of lumen: Smallest, width of red blood cell
Relative thickness of wall: Very thin, one cell thick, flattened endothelial cells
Tunica Interna: Smooth endothelium to aid flow
Tunica Media: None
Tunica Externa: None
Pressure: Lowest

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14
Q

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

A

Pressure drops as moving away from heart
Cross sectional area increases from artery to capillary, lower pressure and slower rate
Cross sectional area decreases, move from capillaries to vein, increase flow rate and pressure, not same extent as arterial vessels

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15
Q

How are veins adapted to having low pressure?

A

Valves to prevent backflow, blood can only flow in One Direction (hahah) and so the low pressure flow doesn’t affect it.

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16
Q

What is plasma?

A

Yellow liquid part of blood, carries dissolved substances such as glucose, amino acids, hormones, ions, large plasma proteins

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17
Q

What is tissue fluid?

A

Similar to plasma, but bathes the cells and tissues and does not contain plasma proteins

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18
Q

What is lymph?

A

Similar to tissue fluid, composition varies, found in lymph vessels. Contains more fat and white blood cells

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19
Q

What is oncotic pressure?

A

Pressure exterted by larger proteins in plasma, ‘pulls’ water into vessel

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20
Q

What is hydrostatic pressure?

A

Pressure due to fluid, higher at arterial and in vessel, higher at venous end in tissues

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21
Q

What is the composition of blood?

A

Plasma takes up 55%, cellular components of buffy coat (WBC + platelets) and red blood cells make up 45%

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22
Q

What are some of the functions of blood?

A

-Transport oxygen, CO2, cells, hormones, ions, platelets, clotting factors, antibodies, nitrogenous waste, products of digestion (glucose, amino acids), storage components of cells
-Regulate internal body temperatures

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23
Q

How is tissue fluid formed?

A

Hydrostatic pressure at arterial end is higher in the blood than in tissue fluid, higher than oncotic pressure
Plasma (w/o proteins) pushed out through fenestrations in capillary, now tissue fluid
As blood flows through capillary, HSP in blood decreases, fluid lost
Reaches point where oncotic pressure and hydrostatic pressure in tissues combined in higher than HSP in blood, fluid moves back into capillary by osmosis

24
Q

What is the purpose of tissue fluid?

A

Fluctuates substance exchange between cells, removes waste products

25
What is the role of lymph and lymph nodes?
Some tissue fluid drains into the lymphatic system through one way valves, preventing fluid building up. The lymphatic system plays a major role in the immune system. Along the lymph vessels there are lymph nodes where lymphocytes accumulates, and these produce antibodies which pass into the blood during infection. Phagocytes engulf and digest pathogens in the lymph, and to prevent a drop in blood pressure, the lymph eventually returns to the blood via the subclavian vein.
26
What causes blood to flow through the heart?
Pressure from atria and ventricles, difference in pressure, fluids move via mass flow, contraction and relaxation
27
What is diastole?
Relaxed
28
What is sistole?
Contracting
29
What is the role of valves in the heart, and how are they adapted to the role?
Valves prevent backflow of blood, meaning that enough blood is able to be transported around the body, and the shape means that pressure on one side opens them, and pressure on the other closes them.
30
Explain the cardiac cycle
-Both atria and ventricles are relaxed -Blood flows into atria -Blood continues through open atrioventricular valves into ventricles -Atrial systole -Both the left and right atria contract together -Increases pressure, pushes blood into ventricles -Once ventricles are full, begin to contract -Increase in pressure closes atrioventricular valves -Prevents backflow -Short period, all closed -Ventricular systole -Pressure rises rapidly -Semi-lunar valves open -Blood pushed into arteries, out of heart -Walls relax -Pressure in arteries forces semilunar valve closed -Cycle repeats
31
Why is it important that the chambers contracting is coordinated?
-Not maximum oxygen/glucose delivery if heart is uncoordinated as heart would beat out of sync, and so not all the blood would exit the heart -Atria may contract too fast/more often than ventricles
32
How does the heart beat?
SAN sends out waves of excitation through walls of both atria, causes atrial systole Blood is forced from atria into ventricles AVN delays wave of excitation until atria have finished contracting, and ventricles are full of blood. The impulse cannot pass directly into ventricles due to a band of nonconducting tissue separates atria from ventricles, slowing down the excitation wave AVN sends a wave down the septum via Purkyne fibres to heart apex. A wave of excitation spreads from apex through ventricle walls, leading to ventricular systole Blood is pushed up through arteries Heart goes into diastole Blood passes from veins into atria and ventricles
33
What does the P wave represent on an ECG?
-Excitation of the atria -Impulse moving on to AVN, where impulse is delayed
34
What does QRS wave represent on an ECG?
-Excitation of ventricles -Impulse moving up through the ventricle
35
What does the T wave represent on an ECG?
-Diastole -Ventricles relax
36
What is bradycardia?
When the heart beats too slowly, below 60bpm
37
What is an ectopic heartbeat?
Extra or skipped heartbeat, normal unless occurring frequently
38
What is an electrocardiogram?
Can be used to monitor and investigate electrical activity within the heart by placing electrodes on skin
39
What is fibrillation?
When the atria/ventricles contract rapidly and disrupt the regular heartbeat
40
What does myogenic mean?
Muscle that can initiate own contraction without need for nervous stimulation
41
What is Purkyne tissue?
Specialised fibres that compose the bundle of His, carry wave of excitation through septum to apex and into ventricle walls
42
What is the sinoatrial node?
Located in upper right atrium, pacemaker, generates wave of excitation
43
What is tachycardia?
A faster heart rate than 100bpm
44
How is oxygen transported in the body
Carried by haemoglobin in RBC
45
Describe the structure of haemoglobin
Complex protein with 4 subunits, each subunit contains a polypeptide chain and haem group, haem group contains a single iron atom in Fe2+ form
46
What is affinity and how does it relate to haemoglobin?
Affinity is attraction, and haemoglobin has an affinity for oxygen, iron molecule can attract and hold an oxygen molecule. Each haemoglobin has four polypeptide chains so four Fe+2 can carry 4 O2
47
Why is oxygen measured in partial pressure?
Partial pressure is pressure exerted by a given gas in a mixture. pO2 is pressure exerted only by oxygen, it is better than using concentration but can be thought of in the same way.
48
How and why is foetal haemoglobin different to adult haemoglobin?
Foetal blood has low pO2 as foetus is respiring, mothers blood only slightly higher pO2 for similar reasons. Greater affinity for oxygen than that of haemoglobin, allowing it to pick up oxygen at partial pressure where adult haemoglobin releases oxygen. Foetal Hb picks up oxygen and holds onto it. Oxygen diffuses out of mothers blood, causing maternal Hb to dissociate more oxygen
49
What are the three ways that CO2 is transported around the body?
Around 5% dissolved in the plasma Around 10% combines with haemoglobin to form carbaminohaemoglobin Around 75-85% is converted to hydrogen carbonate ions in the cytoplasm of RBC
50
Explain how CO2 is transported in RBC
-CO2 diffuse into RBC. React with water, forms carbonic acid, H2CO3 -Catalysed by carbonic anhydrase -Carbonic acid dissociates to form H+ and HCO3- ions -Hydrogen carbonate ions diffuse out of RBC down conc. grad., into blood plasma. Countering this loss of -ve charged ions, chloride ions move into RBC cytoplasm: chloride shift -H+ ions that were formed are taken up by Hb to form haemoglobinic acid, preventing a drop in pH and so Hb acts as a buffer. -When Hb combines with H+ ions, causes oxyHb to release oxygen, diffuses out into plasma and to respiring tissues
51
Explain the Bohr Effect
The Bohr Effect results in oxygen being more readily released when more CO2 is produced from respiration.
52
Explain the Bohr Shift
The Bohr Shift is the shift of the dissociation curve downwards and to the right of the graph
53
Explain the lower section oxygen haemoglobin dissociation curve
At a low pH, the haemoglobin does not readily take up oxygen molecules, as the haem groups that attract the oxygen are in the centre of the haemoglobin molecule, making it difficult for the oxygen molecule to reach the haem group to associate with it. This accounts for the low saturation level of haemoglobin at a low pO2. As pO2 rises, the diffusion gradient into haemoglobin molecules increases, and eventually an oxygen molecule diffuses into the haemoglobin molecule and associates with one of the haem groups, causing a conformational change in the shape of the haemoglobin molecule
54
Explain the middle section of the oxygen haemoglobin dissociation curve
This conformational change allows more oxygen molecules to diffuse into the haemoglobin molecule and associate with the other haem groups relatively easily. This accounts for the steepness of the curve as oxygen partial pressure rises
55
Explain the upper section of the oxygen haemoglobin dissociation curve
Once the haemoglobin molecule contains three oxygen molecules, it becomes more difficult for the fourth molecule to diffuse in and associate with the last available haem group. This means it is more difficult to achieve 100% saturation of all the haemoglobin molecules, and so the curve levels off as saturation approaches 100%

Biology (13 decks)

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