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B4 Flashcards

1
Q

What are the main components of the blood?

A

plasma
platelets
red blood cells
white blood cells

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2
Q

What is the function of the plasma?

A

Transporting carbon dioxide, digested food molecules, urea and hormones; distributing heat

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3
Q

What percentage of the blood does the plasma consist of?

A

55%

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4
Q

What is the role of platelets?

A

involved in blood clotting

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5
Q

How do they help the blood to clot?

A

Platelets release chemicals that cause soluble fibrinogen proteins to convert into insoluble fibrin

This forms an insoluble mesh across the wound

Red blood cells become trapped, forming a clot

The clot eventually dries and develops into a scab

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6
Q

What percentage of the blood do platelets and white blood cells make up?

A

1%

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7
Q

What is the role of white blood cells?

A

White blood cells are part of the body’s immune system. These specialised cells defend against pathogenic microorganisms.

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8
Q

What are the two types of white blood cell?

A

lymphocytes
phagocytes

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9
Q

What are the two types of lymphocytes?

A

T lymphocytes and B lymphocytes

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10
Q

what do b lymphocytes do?

A

recognise specific antigens on invading pathogens and if they detect that they are foreign, produce antibodies

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11
Q

what are antigens?

A

surface proteins

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12
Q

what is the role of antibodies?

A

Antibodies are Y-shaped protein molecules which have binding sites (receptors) specific to particular antigens. When antibodies bind to antigens, the pathogen is inactivated.

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13
Q

What are T lymphocytes?

A

induce apoptosis (programmed cell death) which destroys cells that have been infected by a pathogen
.

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14
Q

How do they carry trigger apoptosis?

A

T lymphocytes attach onto infected cells and release proteins. These proteins diffuse into the infected cells. This causes production of self-destructive enzymes, which cause cell death. The remains of the cell are then removed by
phagocytosis.

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15
Q

What is the role of phagocytes?

A

they engulf pathogens

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16
Q

How do they engulf pathogens?

A

The phagocytes membrane surrounds the pathogen and enzymes found inside the cell break down the pathogen in order to destroy it. As phagocytes do this to all pathogens that they encounter, they are called ‘non-specific’.

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17
Q

What is the role of red blood cells?

A

The red blood cell’s main function is to carry oxygen from the lungs and deliver it throughout our body. Red blood cells also transport waste such as carbon dioxide back to our lungs to be exhaled.

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18
Q

What are the adaptations of red blood cells?

A

They are small and flexible so they can fit through narrow vessels, have a bi-concave shape which maximises their surface area to absorb oxygen, have a thin membrane so gases easily diffuse through, contain haemoglobin which binds to oxygen and don’t have a nucleus to ensure they can carry lots of oxygen

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19
Q

What percentage of the blood do red blood cells make up?

A

44%

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20
Q

What are the adaptations of white blood cells?

A

-can change shape which allows them to squeeze through the walls of blood vessels into body tissues and to engulf harmful microorganisms
-phagocytes contain lysozyme enzymes which break down and digest foreign pathogens
-some lymphocytes stay in the immune system after infection and become memory cells which remember the specific antigen on a pathogen and provide immunity upon re-exposure as they can mount a defence quickly before a person starts to exhibit symptoms

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21
Q

what are the three types of blood vessel?

A

arteries
veins
capillaries

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22
Q

what is the function of arteries?

A

to carry (generally oxygenated) blood (apart from pulmonary arteries) away from the heart

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23
Q

How does the structure of arteries relate to their function?

A

-they have thick muscular walls which are able to withstand the high pressure of blood exerted by heart’s contractions
-walls contain elastic fibres allowing the arteries to stretch and recoil maintaining blood pressure between heartbeats
-small lumen to ensure this pressure is maintained as the blood is transported around the body

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24
Q

What is the function of veins?

A

carry (generally deoxygenated) blood (apart from pulmonary veins) towards the heart

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25
What are the functions of capillaries?
Capillaries are small blood vessels that facilitate the exchange of substances between the blood and body cells. Their one-cell-thick walls allow for diffusion of oxygen, nutrients, and waste products.
26
How are they adapted to their function?
Lumen is very narrow - This small size slows down blood flow, increasing the time for substances to diffuse across the thin capillary walls Walls are thin - Substances can be exchanged across a short distance by diffusion. Highly branched - This provides a large surface area for diffusion.
27
How are veins adapted to their function?
-thinner walls: less strong due to lower pressure + allows for easier compression from nearby tissues aiding in blood flow - large lumen: reduces resistance to blood flow at low pressure -valves: veins contain valves that prevent blood from flowing backward due to low pressure
28
What is a double circulatory system?
In a double circulatory system, the blood passes through the heart twice during one complete circuit of the body
29
Why is this important?
Double circulatory systems allow for higher metabolic rates to be maintained as there is no mixing of oxygenated and deoxygenated blood. This means that blood leaving the heart to travel to the body is rich in oxygen. This is essential for the high-energy demands of birds and mammals.
30
What is the function of the heart?
The functions of the heart are to pump blood and oxygen around the body and deliver waste products (carbon dioxide) back to the lungs to be removed
31
What are the main structures of the human heart?
the heart has 4 chambers: two atria (upper chambers of the heart which receive blood from veins) and two ventricles (the lower chamber of the heart that receives blood from the atrium and pumps it into arteries).
32
What are the two parts of a double circulatory system?
the pulmonary circulation carries deoxygenated blood from the heart to the lungs for oxygenation, while the systemic circulation carries oxygenated blood from the heart to the rest of the body.
33
What route does blood take through the heart?
deoxygenated blood enters the right atrium through the vena cava and moves through the right ventricle. Deoxygenated blood then exits the right ventricle through the pulmonary arteries where it is then pumped to be oxygenated by the lungs. Oxygenated blood is pumped back to the heart from the lungs through the pulmonary veins entering the left atrium and moves through the left ventricle. Blood is then carried away from the heart through the aorta.
34
What issues can develop from blood vessels in the heart?
cardiovascular disease such as coronary heart disease is caused by cholesterol which contributes to the build-up of fatty plaques inside the coronary arteries. Fatty plaques reduce the flow of blood through the coronary arteries This is a problem because the cardiac muscle cells of the heart are supplied with blood by the coronary arteries that branch off directly from the aorta It is vital that this blood reaches these cells in order to supply oxygen for constant respiration
35
What are the treatments for cardiovascular disease?
Stents: used to keep coronary arteries open to aid blood flow Statins: drugs that are widely used to reduce the levels of fatty deposits (cholesterol) in the blood. They block an enzyme in the liver which is needed to make cholesterol. This slows down the rate of fatty material building up in the blood, reducing the risk of CHD occurring.
36
How are stents installed?
A narrow tube is threaded up through the groin up to the blocked vessel A tiny balloon is then inflated The balloon pushes the metal or plastic stent against the wall of the artery, increasing the width of the lumen The balloon and tube are then removed
37
What are the advantages of stents?
- immediate solution - widen lumen - short recovery time -don't lead to an immune response
38
what are their disadvantages?
bleeding or bruising at the catheter insertion site, blood clots forming within the stent, and restenosis (re-narrowing of the artery)
39
What are the advantages of statins?
-lower cholesterol production in the liver -decrease risk of heart attack and stroke -reduce fatty build up -don't remove plaque that has already accumulated in the coronary artery
40
what are the disadvantages of statins
-need to be taken long term - don't remove plaque that has already accumulated in the coronary artery -they aren't suitable for everyone -can have side effects: headaches, diarrhoea, sickness
41
How is the heartbeat maintained?
it is maintained by the sinoatrial (SA) node, a group of specialized cells located in the right atrium
42
Why is it referred to as the heart's natural pacemaker?
This node is also referred to as the heart's natural pacemaker because it generates electrical impulses that trigger the heart to contract and beat.
43
Why might a person need an artificial pacemaker?
Pacemakers are implanted to regulate heartbeats and restore normal rhythm when the heart beats too slowly or irregularly, or if the electrical signals controlling the heartbeat are not transmitted properly.
44
Why might a person object to a heart transplant?
- risk of rejection: T lymphocytes might start to attack the cells of the new heart - immunosuppressants increase risk of infection -scarce availability of heart donors
45
How does an artificial pacemaker regulate an irregular heartbeat?
An artificial pacemaker regulates an irregular heartbeat by delivering electrical impulses to the heart. These impulses stimulate the heart to contract and maintain a regular rhythm, especially when the heart's natural pacemaker (the sinoatrial or SA node) isn't functioning correctly
46
What are the main structures of the gas exchange system?
-bronchus -bronchiole -trachea -intercostal muscles -diaphragm -alveoli
47
where does gas exchange occur?
in the alveoli (tiny air sacs at the end of bronchioles) where oxygen from the air diffuses into the blood and carbon dioxide from the blood diffuses into the alveoli to be exhaled
48
How are the alveoli adapted to increase overall rate of gas exchange?
-millions of alveoli increase surface area which maximises rate of gas exchange -walls are only one cell thick: short diffusion distance -moist surface allowing gases to dissolve into them - rich blood supply maintaining steep concentration gradient-capillaries -bronchioles have good ventilation as oxygen is inhaled and co2 is exhaled maintaining a steep concentration gradient
49
What are the processes of inhaling?
-intercostal muscles contract -diaphragm contracts and moves down -ribcage moves up and out -volume of lungs increases -pressure drops below atmospheric pressure -air rushes in to fill low pressure
50
What processes occur during exhalation?
-diaphragm relaxes and moves up -intercostal muscles relax and move in -ribcage moves down and in - volume of lungs decrease -pressure increases above atmospheric pressure -air rushes out
51
What are the functions of the xylem and phloem?
Xylem transports water and mineral salts from the roots up to other parts of the plant Phloem transports sucrose and amino acids from the leaves and other parts of the plant.
52
what adaptations do the xylem have to aid their function?
-made up of dead cells that have lost their end walls, creating a continuous, hollow tube:
53
adaptations of the phloem?
The cells are elongated and join end to end with sieve plates in between them. Sieve plates have pores that allow cell sap to flow through. The cells are living but have very few subcellular structures so substances can pass through easily. Substances can move both directions in the vessel so they can get to where they are most needed.
53
What are the different tissues in a cross-section of a leaf?
-upper epidermis -palisade mesophyll -spongy mesophyll -lower epidermis
54
54
what are the adaptations of the epidermal layers?
-upper: waxy cuticle to reduce water loss through transpiration transparent to allow light penetration for photosynthesis -lower: lots of guard cells and stomata (more so than on the upper epidermis) as there is less light exposure which reduces water loss through transpiration
55
what are the adaptations of the palisade mesophyll layer?
lots of chloroplasts which absorb light energy from the sun and convert it into usable energy in the form of glucose
56
what are the adaptations of the spongy mesophyll layer?
lots of air spaces which provide space for gases to diffuse in and out of the cell
57
How do guard cells control the opening and closing of the stomata?
. In bright light the guard cells take in water by osmosis and become plump and turgid .In low light the guard cells lose water and become flaccid
58
What is the process of moving food substances in the phloem called?
translocation
59
What process transports water in the xylem?
the transpiration stream
60
How is water pulled up through the xylem?
The transpiration stream is a process where, when water evaporates from the leaves through the stomata, a suction is created pulling water and dissolved minerals up the plant: the more water lost, the more water absorbed by the roots
61
How does temp affect rate of transpiration?
Temperature– The higher the temperature, the more the molecules move. This means more water evaporates from cell surfaces and diffuses out of the leaf which increases the rate of transpiration.
62
What is transpiration?
The loss of water from plant leaves
63
How does humidity affect the rate of transpiration?
Humidity– The lower the humidity, the lower the concentration of water outside of the leaf. This means there is a steeper concentration gradient, water will diffuse out of the leaf faster and therefore the transpiration rate will increase.
64
How does air movement affect the rate of transpiration?
Air movement– Increased air flow around the leaf also decreases the concentration of water outside the leaf, increasing the concentration gradient and rate of transpiration.
65
How does Light intensity affect the rate of transpiration?
Light intensity– In light, the guard cells become turgid and open the stomata. This increases water loss and the transpiration rate
66
How can a potometer be used to estimate the volume of water lost from a plant?
The rate of transpiration can be calculated by measuring the distance travelled by an air bubble in a capillary tube over a given time. The faster the bubble moves, the greater the rate of water uptake – and so the greater the assumed rate of transpiration
67

Biology (4 decks)

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