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Biology > Module 3- Transport in animals > Flashcards

Module 3- Transport in animals Flashcards

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1
Q

What can the direction of blood flow be controlled by?

A

Contracting the arterioles to restrict blood flow and relaxing to allow blood flow

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2
Q

What are venules?

A

-small blood vessels that collect blood coming out of capillaries
-blood flows from the vast network of capillaries into a network of fewer but larger venules and will eventually flow into veins.

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3
Q

What is the diameter range of a venule?

A

7 micrometers to 1 mm

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4
Q

What is the role of the artery and describe its features

A

-transport blood away from the heart into the organs
-artery walls have thick layers of muscle which maintain a high pressure so blood can be pumped around the body
-elastic fibres in the artery walls allow the arteries to stretch
-the endothelium is folded which also allows the arteries to stretch

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5
Q

What is the role and structure of veins?

A

-veins transport blood back to the heart
-the lumen is wider than the arteries which allows blood to flow at a low pressure
-there is a thin muscle wall and elastic tissue
-valves are located throughout the veins to ensure that blood flows towards the heart

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6
Q

What is the role and structure of capillaries?

A

-capillary walls (endothelium) are only one cell thick, this means that the diffusion distances are very short allowing for efficient gas exchange
-they pass very close to the body cells
-form networks (capillary beds) around body cells which create a large surface area

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7
Q

What is the structure and function of tissue fluids?

A

-transport substances via the tissue fluids
–combination of oxygen, water and nutrients
-surrounds cells in the body
-substances in the tissue fluid can diffuse or be transported into cells

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8
Q

What is pressure filtration?

A

where substances move into the tissue fluid from the capillaries

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9
Q

How is a high pressure gradient maintained in the capillaries?

A

-high volume of blood being forced through narrow capillaries creates high hydrostatic pressure in the capillaries at the entrance of the capillary bed
-this causes a high pressure gradient between inside the capillaries and outside

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10
Q

What causes a decrease in pressure in capillaries?

A

-movement of fluid out of the capillaries causes the hydrostatic pressure inside the capillaries to decrease
-so capillary bed pressure is lower at the entrance than at the exit

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11
Q

What is the water potential gradient in capillaries?

A

-when fluid moves out of the capillaries, plasma proteins remain inside the capillaries
-the plasma protein concentration inside the capillaries increases and the water potential decreases
-a water potential gradient is established and water diffuses via osmosis back into the capillaries from the tissue fluid
-oncotic pressure pulls water back into the capillaries and is created by the increased plasma protein concentration.
-it is the opposite to hydrostatic pressure which forces pressure out of the capillaries.

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12
Q

What is the lymphatic system?

A

-excess tissue fluid flows into the lymphatic system
-it recycles the excess tissue fluid into the blood stream

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13
Q

Describe the flow of blood in the human body starting from deoxygenated blood flowing into the right atrium

A

1)deoxygenated blood flows into the right atrium from the body through the vena cava
2)when the walls of the right atrium contract, deoxygenated blood flows into the right ventricle
3)the atrioventricular valves prevent blood flowing back into the atria from the ventricles
4)the walls of the right ventricle contract and blood is pumped out of the pulmonary artery to the lungs
5)the semi lunar valves prevent blood flowing back into the ventricle from the pulmonary artery
6)oxygenated blood flows into the left atrium from the lungs through the pulmonary vein
7)when the walls of the left atrium contract oxygenated blood flows into the left ventricle (walls are a lot thicker than the right)
8)when the left ventricle contracts blood is pumped out of the heart through the aorta to the rest of the body.

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14
Q

What should you consider before dissecting the heart?

A

-blades must be sharp to allow for clean cuts
-use gloves

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15
Q

How would you open the heart during dissection?

A

slicing carefully from the aorta around the outside edge

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16
Q

Describe the pressure changes in the atria

A

-when the atria contract, pressure in the atria increases
-when the atria relax and the ventricles contract the pressure in the atria decreases
-when both the atria and ventricles are relaxed there is a slight increase in pressure as the atria fill with blood again

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17
Q

Describe the pressure changes in the ventricles

A

-when the ventricles contract, the pressure increases dramatically as they contract significantly more than the atria contract

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18
Q

Where is the sinoatrial node located?

A

-wall of the right atrium

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19
Q

How does the SAN act as a pacemaker?

A

By transmitting waves of electrical activity along the walls of the atria at regular intervals this causes the right and left atria to contract together forcing blood from the atria into the ventricles

20
Q

Why can’t the waves of eletrical activity pass from the atria to the ventricles?

A

due to a collection of non conducting tissue creating a delay to ensure the atria are empty before the ventricles contract

21
Q

What happens to the electrical activity after it passes through the AVN?

A

-goes to the bundle of his which is a collection of conducting tissue that transmits the electrical activity to the apex (bottom) of the heart and around the ventricle walls along fibres called purkinje fibres
-as the wave of electrical activity passes along the fibres the ventricles contract together and blood is forced out of the heart

22
Q

Electrocardiograms all have what 3 things?

A

P wave
QRS complex
T wave

23
Q

What is the P wave in ECG traces?

A

represents depolarisation of the atria as the impulse passes from teh SAN to the AVN

24
Q

What is the QRS complex in ECG traces?

A

represents depolarisation of the ventricles as the impulse passes through the bundle of his and purkinje fibres

25
Q

What is the T wave in ECG traces?

A

represent the repolarisation of ventricles

26
Q

What is the pause between the P wave and QRS complex?

A

after depolarisation of the atria the impulse is held at the AVN before moving down the bundle of his to depolarise the ventricles

27
Q

What part of the ECG trace determines the heart rate?

A

the frequency of each PQRST cycle
so if the cycles are very close together this indicates a fast heart rate

28
Q

What is tachycardia?

A

heart condition that involves a resting HR of over 100 bpm

29
Q

What is bradycardia?

A

abnormally slow hr (below 60 bpm)

30
Q

What is arrhythmia?

A

an irregular heart beat

31
Q

What is atrial fibrilation

A

condition involving a lack of coordinated atrial depolarisation
-the ecg trace won’t have a p wave

32
Q

Structure of haemoglobin

A

-globular protein
-4 different polypeptide chains
-haem groups contain an iron ion which is what makes it red

33
Q

Function of haemoglobin

A

-when rbc reaches the tissue in the body oxygen is released from the oxyhaemoglobin in dissociation
-haemoglobin has a high affinity for oxygen
-4 molecules of oxygen bind to one molecule of haemoglobin and oxyhaemoglobin is formed

34
Q

What is oxygen partial pressure?

A

concentration of oxygen in cells and is important in determining whether oxygen binds to haemoglobin

35
Q

What happen is pO2 is too low?

A

haemoglobin has a low affinity for oxygen and will dissociate from haemoglobin

36
Q

What is carbonic anhydrase?

A

enzyme that converts CO2 into a carbonic acid in RBC then back into CO2 when it reaches the lungs

37
Q

What does carbonic acid do?

A

-dissociates into bicarbonate ions and hydrogen ions in the blood

38
Q

How is pH maintained?

A

by buffering agents such as haemoglobin that bind with hydrogen ions to prevent a fall in pH

39
Q

What is the chloride shift?

A

in order to move bicarbonate ions outside RBC they must be swapped with Cl ions from blood plasma which maintains the neutrality of the cell

40
Q

What is a dissociation curve?

A

-relationship between percentage saturation of haemoglobin and oxygen partial pressure of surrounding tissue

41
Q

When is percentage saturation low?

A

is oxygen dissociates from haemoglobin

42
Q

What is conformational change?

A

when the first molecule of O2 binds to haemoglobin the protein undergoes conformational change. This change in shape allows other O2 molecules to bind to haemoglobin more easily so percentage saturation increases quickly

43
Q

Why does percentage saturation begin to plateau?

A

as it begins more difficult for O2 molecules to bind

44
Q

What is the bohr effect?

A

-partial pressure of CO2 also influences the affinity of haemoglobin for oxygen
-respiring cells use O2 and produce CO2 so have low pO2 and high pCO2 which is where the rate of oxygen dissociation increases
-this causes a shift of the curve to the right as the oxygen will dissociate at a lower pO2 than normal

45
Q

What are the differences between adult and fetal haemoglobin?

A

-adult haemoglobin receives oxygen from the air via the lungs whereas fetal haemoglobin binds to oxygen that is already in adult blood
-adults haemoglobin have 2 beta chains but fetal have 2 gamma chains which have a higher affinity for oxygen

46
Q

What is the oxygen saturation curve like for fetal haemoglobin?

A

-it is steeper as it more readily binds to oxygen

Biology (13 decks)

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