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Animal Transport Flashcards

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1
Q

What is the need for animal transport?

A

Size:

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2
Q

What are the features of an effective transport system?

A
  • A fluid to carry oxygen, glucose , amino acids , fatty acids and glycerol around the blood using blood for example
  • Exchange surfaces that oxygen , glucose etc to enter and leave the blood
  • A pump to create pressure that will push the fluid around the body
  • An effective transport system will include : tubes and vessels to carry the blood and two circuits - one to pick up oxygen and another to take it to the vessels
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3
Q

What are the different types of transport systems?

A

Closed circulatory systems
- Vertebrates have closed circulatory systems : vertebrates (mammals and fish) have a closed circulatory system, this means that their blood stays entirely inside the vessels
- A separate fluid bathes the cells - tissue fluid
Open circulatory systems
- Blood is not always contained within vessels but circulates the body cavity which is called the haemocoel (blood space)
- Cells are bathed directly in blood
- Insects still have hearts to pump blood around the body
- They squeeze blood towards the head where it flows out of the haemocoel. Some larger insects have open ended arteries to help direct the blood
- Body movements can help move the body

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4
Q

What are single and double circulatory systems?

A
  • Single circulatory systems: Blood only flows through the heart once for each complete circuit of the body
  • Double circulatory systems :Blood flows through the heart twice for each complete circuit of the body
    Advantages:
  • blood pressure can be increased after it has gone to the lungs then back to the heart which will supply more oxygen and glucose to the body tissue
  • systematic circulation can carry blood at a higher pressure then the pulmonary circulation
  • lower pressure of blood in the pulmonary system prevents damage to delicate capillaries in the lungs
  • Blood is pumped from the heart - to the lungs -then back to the heart = pulmonary circulation
  • Blood is pumped from the heart -to the body - then back to the heart = systemic circulation
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5
Q

What are blood vessels?

A

Blood flow through the body
- Blood leaves the heart in arteries
- The largest arteries divide to form much smaller vessels called arterioles
- Arterioles divide into vessels called capillaries
- Capillaries join up together to form venules
- Venules merge to form veins which carry blood back to the heart
- Inner layer (tunica intima) - the endothelium and relatively thin layer of elastic tissue
- Middle layer (tunica media) - thick layer mainly composed of thick muscle
- Outer layer (tunica externa / adventia ) - relatively thick layer of collagen and elastic tissue

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6
Q

What are the features of arteries?

A
  • Carry blood at high pressure away from the heart
  • The artery wall is relatively thick to withstand pressure
  • The lumen is relatively narrow or maintain pressure
  • The inner wall is elastic and folded to allow the lumen to expand
    Structure
  • relatively narrow lumen
  • Collagen and some elastic fibres - provides strength to withstand pressure and recoil to maintain the pressure (tunica externa)
  • Thick layer of smooth muscle and elastic fibres - collagen fibres constrict and dilate the vessels (tunica media)
  • Folded endothelium - made of simple squamous cells , smooth - expand with blood flow and a layer of elastic tissue allows the wall to stretch and recoil
  • Arterioles have similar structure to arteries - more smooth muscle and fewer elastic fibres in their walls
  • Smooth muscle allows vasoconstriction and vasodilation when it relaxes
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7
Q

What are the features of capillaries?

A
  • Allows for exchange of materials between blood and tissue fluid
  • Capillaries often form networks Increasing SA in contact with tissue (exceptions in the cornea and cartilage)
  • The lumen is very narrow which shortens three diffusion path to tissues and reduces the rate of flower dunes th
  • The lumen is very narrow which shortens the diffusion path to tissues and rate of flow
  • Walls are one cell thick - flattened endothelial cells
  • The walls are leaky - allowing plasma and dissolved substances to leave the blood
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8
Q

What are the features of the vein?

A
  • Venules and veins carry low pressure blood to the heart
  • They have thinner walls then arteries as they do not need to withstand pressure
  • The lumen is relatively large to reduce resistance to the flow
  • little smooth muscle as it doesn’t benefit the veins at all
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9
Q

What are the features of valves?

A
  • Too return the blood at low pressure veins are squeezed by surrounding muslces .
  • Valves prevent back flow
  • These are flaps of infolded endothelium
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10
Q

What are the features of the heart ?

A
  • Consists of two muscular pumps. The right hand side pumps deoxygenated blood to the lungs.The left hand side pumps oxygenated blood around the rest of the body.
  • The heart lies slightly towards the left of the chest cavity.It consists mainly of firm, dark cardiac muscle
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11
Q

What is the role of the coronary arteries?

A
  • Supply the heart muscle with oxygen and nutrients (glucose) so that that the muscle can respire aerobically.
  • Cardiac veins remove waste carbon dioxide
  • Restricted flow in these vessels can cause angina and a blockage of these arteries leads to myocardial infarction ( heart attack) because the heart muscle is deprived of oxygen then dies.
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12
Q

What some key internal features of the human heart?

A
  • The septum prevents the mixing of deoxygenated and oxygenated blood
  • Atria have thin muscular walls as they do not need to create as much pressure as the ventricles
  • Atria and ventricle are separated by atrioventricular valves - tricuspid on the right and bicuspid on the left . They help to prevent back flow of blood and are attached to tendinous cords which prevent the valves from flapping upwards and hold them in place
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13
Q

What is the role of the two main arteries in the heart?

A
  • Aorta artery from the left ventricle to the head and body
  • Pulmonary artery from the right ventricle to the lungs - deoxygenated blood
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14
Q

What is the role of the two major veins in the heart?

A
  • Vena cava from the body and head into the right atrium
  • Left pulmonary vein from the lungs into the left atrium - oxygenated blood
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15
Q

What is the structure of myocardium ( cardiac muscle structure)?

A
  • Cardiac muscle is myogenic – it can generate its own excitory impulse. It contracts and relaxes without any stimulation from nerves.
  • The cells are branched producing cross bridges – these help spread the contraction and allows the heart to produce a squeezing force.
  • The cells are joined by intercalated discs which facilitate synchronised contraction.
  • Like other muscles it contains many mitochondria carry out aerobic respiration to release the energy needed for contraction.
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16
Q

How does the features help cardiac muscle structure?

A
  • Intercalated discs help ensure synchronised contraction
  • Each cell has one nucleus and is divided into contractile units called sarcomeres
  • There are many mitochondria between the muscle fibrils (myofibrils) to supply energy for contraction
  • Branched cardiac muscle fibres - cross bridges help to spread the contraction to produce a squeezing actions
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17
Q

In the cardiac cycle what takes place at atrial systole ?

A
  • Muscle in the walls of both atria contract.
  • There is a small increase in pressure. This is not very great because the walls of the atria are thin .
  • However, it is enough to force blood into the ventricles through the atrioventricular valves (already open)
  • This helps the ventricles to fill with blood and stretches their walls.
  • Blood does not flow back into the pulmonary vein or vena cava as the semi lunar valves are forced closed preventing backflow.
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18
Q

In the cardiac cycle what takes place at ventricular systole?

A
  • About 0.1s after the atria contract the thick muscular walls of the ventricles contract.
  • This increases the pressure.
  • The pressure in the ventricles becomes higher than in the atria and this pushes the atrioventricular valves shut.
  • The high pressure in the ventricles also forces open the semi lunar valves in the aorta and pulmonary artery.
    -Blood is forced into the aorta and artery
  • This ventricular systole lasts about 0.3s.
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19
Q

In the cardiac cycle what takes place at diastole?

A
  • The atria and ventricles both relax .
  • Elastic tissue recoil helps to return the ventricles to their original size.
  • The pressure in the ventricles decreases .
  • The higher pressure in the pulmonary artery and aorta forces the semi-lunar valves to close to prevent backflow.
  • Blood from the veins flows into the two atria .
  • Because the ventricles are relaxed and the atria are filling with blood the pressure in the atria becomes higher the pressure in the ventricles.
  • This opens the atrioventricular valves.
  • Blood begins to flow into the ventricles .
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20
Q

What is the sound that can be head when our hearts beat?

A

The lub-dub sound of the heart is caused by valves closing
- Lub = snapping shut of atrio-ventricular valves
- Dub = shutting of semilunar valves

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21
Q

Control of the cardiac cycle?

A
  • Cardiac muscle is myogenic therefore cells grown in culture will contract and relax rhythmically
  • Cardiac cells joined together contract in unison
  • These contractions need to be coordinated to prevent fibrillation and ensure the efficient pumping of blood.
22
Q

How does atrial contraction aid in the control of the cardiac cycle?

A
  • The cardiac cycle is initiated by the sino-atrial node (SAN)
  • This is a small patch of tissue in the wall of the right atrium
  • This initiates an electrical wave of excitation (depolarisation)
  • This passes over the walls of both atria causing them to contract
  • A band of non-conducting collagen fibres between the atria and ventricles prevent the electrical wave passing through to the ventricles
23
Q

How does ventricular contractions aid in control of the cardiac cycle?

A
  • A small gap in the non-conductive collagen fibres at top of the septum known as the atrio-ventricular node (AVN) allows the wave of depolarisation through with a small delay (0.1s)
  • The electrical wave then travels down conductive Purkyne tissue which run down the septum
  • This transmits the excitation very rapidly to the apex of the ventricles
  • Purkyne tissue then conducts the electrical wave upwards and outwards through the ventricle walls
  • This causes the muscles to contract from the bottom up
24
Q

Why must the wave of excitation not spreads into the ventricles at the same time as it spreads across the atrial walls?

A

The ventricles would not have enough time to fill with blood and not enough blood would be pumper around

25
Q

Why should the ventricles contract from the bottom up?

A

To ensure all the blood has left the ventricle and none is left in.

26
Q

The nervous and endocrine (hormonal system) can alter the heart rate by changing the pace of the SAN . What’s could cause these changes to be initiated?

A
  • Two nerves carry impluses from the brain to the SAN:
    • Vagus nerve : releases a transmitter substance called acetylcholine next to the cells in the SAN. Shots into the receptor in the plasma membrane of the cells and makes the ells beat more slowly
    • Sympathetic nerve : causes the cells in the SAN to beat more rapidly . Adrenaline has the same effect
27
Q

What drugs help people with their rate of heartbeat?

A
  • Digoxin : inhibits a Na-K pump in the plasma membrane of the heart muscle cells causes increased sodium so the fore of muscle contraction
  • Propranol : beta blocker decreases the effect of noradrenalin on the SAN reducing the heart rate
28
Q

What are are electrocardiograms (ecg)

A
  • An ECG measures the tiny electrical differences in your skin, which result from the electrical activity of your heart.
  • Electrodes are placed on the skin over opposite sides of the heart, and the electrical potentials generated recorded with time. The result is an ECG.
  • The trace produced can be used to diagnose heart conditions, such as arrhythmias and fibrillation.
29
Q

What is the different compostions of substances within the blood?

A
  • 55% plasma - water, CO2 , mineral ions, hormones, urea, plasma proteins,glucose and amino acids
  • 1% platelets and white blood cells ( leucocytes)
  • 44% red blood cells (erythtrocytes)
30
Q

What is tissue fluid?

A
  • Tissue fluid is the fluid that bathes cells in tissues
  • It is formed from the plasma that leaks out of capillaries
  • It is essential for the exchange of materials between our cells and our blood:
    • cells absorb oxygen and nutrients from the tissue fluid and release carbon dioxide and other metabolic wastes into it.
31
Q

How is tissue fluid formed?

A
  • At the arteriole end of the capillary blood is at relatively high hydrostatic (blood) pressure.
  • This is pushing fluid through the gaps in capillary walls
  • The tissue fluid has a relatively small hydrostatic pressure working in the opposite direction
  • Oncotic pressure will also affect the movement of fluids.
  • This is similar to water potential but is due presence of plasma proteins.
  • Therefore at the arteriole end of the capillary there is a net pressure forcing fluid out of the capillary
32
Q

How is tissue fluid returned back into the blood?

A
  • At the venule end of the capillary the hydrostatic (blood) pressure is much lower due to the loss of fluid .
  • However, the plasma proteins are too large to fit out through the gaps in the capillary walls so there is still oncotic pressure
  • Therefore at the venule end of the capillary there is a net movement of fluid into the capillary due to oncotic pressure
33
Q

What is the definition of hydrostatic pressure and oncotic pressure?

A
  • HYDROSTATIC PRESSURE
    The pressure exerted by a fluid
  • ONCOTIC PRESSURE
    The pressure created by the osmotic effects of the plasma proteins
34
Q

What is lymph ?

A
  • About 90% of the fluid that leaks from capillaries is returned to them
  • The remaining 10% is collected and returned to the blood system via a series of tubes called lymph vessels
  • These are tiny blind – ending vessels found in
    almost all tissues of the body
35
Q

What is the lymphatic system?

A
  • Valves in lymph vessel wall allows tissue fluid to flow in but not out
  • These valves allow proteins through this is important because most proteins are to large to enter the capillaries
  • The fluid inside lymphatics ( lymph ) is similar to tissue fluid but has less oxygen , more carbon dioxide and more lymphocytes.
  • A higher concentration of lipid is found in lymph in the walls of small intestines because lipids are absorbed into lacheals in the villi
36
Q

More information on lymph

A
  • Lymph is eventually transported to the subclavian veins
  • Contraction of muscles surrounding lymph vessels helps move it
  • Valves prevent backflow
  • Lymph flow is slow – 100cm3 per hour through thoracic duct
  • Lymphocytes are produced in the lymph nodes. These are an important part of the immune system
37
Q

What are adaptations of erythrocytes?

A
  1. Very small (approx. 7–8 µm diameter):
    - Short diffusion distance
    - squeeze through capillaries so in close contact with the tissues
  2. Biconcave disc = larger SA:V ratio
  3. No nucleus, no mitochondria and no ER: this leaves more space for haemoglobin:
    - This combines reversibly with oxygen to form oxyhaemoglobin
    - there are about 280 million molecules of haemoglobin in every red blood cell each one can carry 8 oxygen atoms
38
Q

What is haemoglobin?

A
  • Haemoglobin is a globular protein molecule,
    made of 4 polypeptide chains.
  • Each polypeptide has a haem prosthetic group containing a single iron ion (Fe2+)
  • The haem group has an affinity for oxygen: the iron ion can attract and hold one oxygen molecule.
  • In the lungs, oxyhaemoglobin is formed . The reaction is reversible. In the body tissues the oxygen is released. This is dissociation or unloading. Hb + 4O2 = HbO8
39
Q

Describe taking up oxygen

A
  • In the alveoli of the lungs oxygen molecules diffuse into the blood plasma
  • Oxygen molecules bind to the haemoglobin forming oxyhaemoglobin
  • Taking the oxygen out of solution maintains a steep concentration gradient
  • Therefore more oxygen enters the blood and diffuses into the red blood cells
40
Q

Describe releasing oxygen

A
  • Oxygen molecules are needed in the tissues for aerobic respiration.
  • Oxyhaemoglobin dissociates releasing the oxygen.
41
Q

What is partial pressure of oxygen and haemoglobin saturation?

A
  • Haemoglobin’s affinity for oxygen varies depending on the conditions it is in, particularly the partial pressure of oxygen (pO2).
  • pO2 is a measure of oxygen concentration
  • As pO2 increases, so does Hb’s affinity for oxygen:
  • Oxygen loads onto Hb to form oxyhaemoglobin where there’s a high pO2
  • Oxyhaemoglobin unloads its oxygen where there’s a lower pO2
42
Q

Alveoli in lungs

A

Alveoli in lungs
- High pO2 (12 - 14kPa)
- Hb has a high affinity for O2
- Oxygen LOADS
- Hb 96 – 97% saturated

43
Q

Respiring tissue

A

Respiring tissue
- Low pO2 (2 - 5kPa)
- Hb has a low affinity for O2
- Oxygen UNLOADS
- Hb 20 – 70% saturated

44
Q

Why is the dissociation curve S shaped?

A
  1. The first O2 molecule combines relatively slowly with the first haem group. Therefore, the first part of the curve is not very steep. However, the binding of oxygen with the first haem group causes the shape of the whole haemoglobin molecule to change. (Conformational change)
  2. As a result of its altered shape, it is much easier for the second and third O2 molecules to bind to their haem groups. Therefore, the curve becomes much steeper.
  3. The curve flattens off because it then becomes harder for the fourth (i.e. the last) oxygen molecule to combine with the fourth haem group.
  • The same shape changes occur during dissociation.
45
Q

Transport of cardon dioxide

A
  • Carbon dioxide is carried in the blood in three ways:
    1. 5% of CO2 is carried dissolved in the plasma
    2. 10% CO2 combines directly with the haemoglobin forming carbaminohaemoglobin
    3. 85% CO2 diffuses into the erythrocytes where the enzyme carbonic anhydrase catalyses this reaction:
    CO2 + H2O = H2CO3 (carbonic acid)
    This dissociates into:
    H2CO3 = H+ + HCO3-
    (Carbonic acid = hydrogen ions + hydrogen carbonate ions)
    = are meant to be forward arrows
46
Q

What is the chloride shift?

A
  • The hydrogen carbonate ions diffuse out of the erythrocyte into the plasma. This causes chloride ions to enter the erythrocyte to balance the charge.
47
Q

What is Bohr effect ?

A
  • The H+ ions could cause an increase in cell acidity. However, haemoglobin acts as a buffer, taking up the H+ ions to form haemoglobinic acid.
  • This reduces the affinity of haemoglobin for oxygen
  • Oxyhaemoglobin releases its oxygen
  • The faster the rate of respiration the higher the concentration of carbon dioxide so more hydrogen ions are produced therefore more oxyhaemoglobin dissociates
    H+ + HbO8 = HHb + 4O2
    =. Meant to be a forward arrow
48
Q

Further information on the Bohr effect

A
  • The formation of haemoglobinic acid means that when there is a higher pCO2 haemoglobin is less saturated with oxygen.
    The dissociation curve shifts to the right. This is called Bohr shift.
  • This means that oxygen is more readily supplied to respiring tissues.
49
Q

Myoglobin

A
  • Skeletal muscle contains a pigment called myoglobin.
  • This has similar structure and function to haemoglobin and acts as an oxygen store in the muscle.
  • Its oxygen dissociation curve lies to the left of that for haemoglobin so that it can bind to oxygen that haemoglobin is releasing.
  • Myoglobin will only release oxygen at very low partial pressures of oxygen.
50
Q

Feral haemoglobin

A
  • A fetus obtains all its oxygen from its mother’s blood across the placenta.
  • Fetal and mother bloods don’t mix, but vessels pass close enough to allow the diffusion of molecules from one to the other.
  • Fetal haemoglobin has a higher affinity for oxygen than adult haemoglobin. Therefore the oxygen dissociation curve for fetal haemoglobin is to the left of adult haemoglobin

Biology (13 decks)

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