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Biology > B5 - the living body > Flashcards

B5 - the living body Flashcards

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0
Q

What are the features of a long bone?

A

A long bone consists of a long shaft containing bone marrow with blood vessels. At each end there is a head covered with cartilage.

Long bones are hollow, so they are stronger and lighter than solid bones

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1
Q

What advantages does an internal skeleton have over an external skeleton?

A
  • it provides an internal framework for the body
  • it grows with the rest of the body
  • it is flexible, due to many joints
  • it allows easy attachment of muscles
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2
Q

Why can cartilage and bone be infected by bacteria and viruses?

A

Because they are living tissues. However, thy are able to grow and repair themselves.

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3
Q

What is the process of ossification and how does it relate to someone’s growth?

A

In very early stages, the human skeleton is made of cartilage. By the process of ossification (the deposition of calcium and phosphorus) the cartilage is slowly replaced by bone. If some cartilage remains between the head and shaft, the bone and person is still growing.

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4
Q

The bones of elderly people lack calcium and phosphorus, what can this lead to?

A

Osteoporosis, making them prone to fractures.

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5
Q

Why can it be dangerous to move someone with a suspected bone fracture?

A

Broken vertebrae in the backbone can damage the spinal cord, resulting in paralysis or death.

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6
Q

What are synovial joints?

A

Synovial joints, such as ball and socket joints and hinge joints, contain synovial fluid, a synovial membrane, ligaments and cartilage.

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7
Q

The forearm is raised and lowered bb antagonistic muscles, the biceps and triceps:

A
  • to raise the forearm, the biceps contracts an the triceps relaxes
  • to lower the forearm, the biceps relaxes and the triceps contracts
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8
Q

Each part of a synovial joint has a special function. What are these functions?

A
  • the synovial fluid acts as a cushion against shock and a lubricant for easy movement
  • a synovial membrane holds in the synovial fluid
  • cartilage protects the bone head
  • the ligaments hold the bone in place
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9
Q

What is raising and lowering the forearm an example of?

A

Raising and lowering the forearm is an example of a lever, with the elbow acting as a fulcrum (pivot). The effort is multiplied resulting in a greater force.

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10
Q

Why do many animals need a blood circulatory system?

A

Many animals need a blood circulatory system to ensure all their cells receive enough food and oxygen to remove waste products, such as carbon dioxide.

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11
Q

What happens to blood pressure as blood flows through arteries, veins and capillaries?

A

The blood pressure decreases. Veins have valves to ensure there is no backward blood flow. High blood pressure would damage the fragile walls of the capillaries.

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12
Q

Describe a double circulatory system.

A

A double circulatory system requires a four chambered heart: two atria to receive blood (from the lungs and body) and two ventricles to distribute blood (to lungs and body). It ensures high blood pressure for efficient and fast circulation of food and oxygen.

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13
Q

Describe a single circulatory system.

A

A single circulatory system needs only two chambers in the heart, one to receive and one to distribute blood.

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14
Q

What is the cardiac cycle?

A

The cardiac cycle is the sequence of events as blood enters and leaves the heart.

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15
Q

What happens during the cardiac cycle?

A

The muscles of the two atria contract together as the two ventricles relax to receive blood through the atrio-ventricular valves, which prevent backward flow into the atria. Muscles of the two ventricles then contract together to force blood to the lungs or around the body. Semi-lunar valves preventer backward flow into the ventricles.

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16
Q

What do pacemaker cells do?

A

Groups of cells in the heart form pacemakers, which control the rate of heart beat by producing a small electric current to stimulate muscle contraction.

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17
Q

What can an artificial pacemaker do?

A

An artificial pacemaker can be placed near the heart to send an electrical signal to the heart muscle.

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18
Q

When can heart rate be increased?

A
  • increasing muscular activity

- the presence of the hormone adrenaline to prepare the body for ‘fight or flight’

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19
Q

What can an electrocardiogram and an echocardiogram do?

A

An ECG shows changes in electrical impulses in the heart muscle

An echocardiogram displays a video of the heart in action

Both can be used to investigate irregular heart actions

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20
Q

What do these two pacemakers do; the sino-atrial node (SAN) and the atrio-ventricular node (AVN)?

A

The SAN and the AVN generate electrical impulses to coordinate heart muscle contraction.

Impulses from the SAN cause the atria to contract and stimulate the AVN. Impulses from the AVN cause the ventricles to contract.

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21
Q

What does a ‘hole in the heart’ cause?

A

A hole in the heart causes the mixing of oxygenated and deoxygenated blood, resulting in the arterial blood carrying less oxygen.

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22
Q

How is the circulation in an unborn baby different from its circulation after it is born?

A

The circulation in an unborn baby is different from its circulation after it is born since the lungs do not function until it is born. An unborn baby therefore does not need a double circulatory system. Before birth, a hole exists between two sides of the heart which closes at birth.

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23
Q

How can damaged or weak valves be fixed?

A

They can be repaired or replaced by surgery.

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24
Q

How can a blocked coronary artery be fixed?

A

A blocked coronary artery reduces the blood flow to the heart muscles. It can be by-passed by transplanting a blood vessel from another part of the body.

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25
Q

How can major heart problems be corrected?

A

By transplanting donor hearts. Small electrical pumps (heart assist devices) can also be used to provide extra pressure to blood leaving the heart, so allowing time for damaged muscle to recover.

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26
Q

What are the advantages and disadvantages of artificial pacemaker and artificial valves?

A

They keep patients alive and improve their quality of life. There are also no problems of donor shortage and finding tissues matches.

Surgery carries a risk, especially the major surgery of a heart transplant. Preventing rejection of a transplant also involves lifetime use of immuno-suppressive drugs.

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27
Q

What is a blood transfusion?

A

A blood transfusion puts the correct blood type into the patient’s blood system, replacing blood lost after an accident or operation.

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28
Q

What drugs can doctors use in blood transfusions?

A

Warfarin, heparin and aspirin to prevent clotting, which can block blood vessels in some medical conditions.

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29
Q

What are people who suffer from the condition haemophilia at risk of?

A

Internal bleeding from the slightest knock, as the blood does not clot.

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30
Q

What happens during the process of blood clotting?

A

The process of blood clotting is called a cascade process as it involves many steps. When blood platelets are exposed to the air at a wound site, it triggers a complex sequence of chemical reactions, eventually leading to the formation of a mesh work of fibrin fibres (clot).

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31
Q

When does agglutination occur?

A

A reaction called agglutination (blood clumping) takes place when different blood groups are incompatible. When agglutinins in red blood cells and plasma react, the blood transfusion endangers the patient’s life.

32
Q

Which antigens will react to cause agglutination?

A

Antigen A will react with anti-A,

antigen B will react with anti-B

33
Q

How does an amphibian take in oxygen and what is a problem of this?

A

Amphibians have simple lungs, but use their moist, permeable skin to obtain oxygen. The permeable skin makes them susceptible to excessive water loss, which can result in death. Fish gills obtain oxygen from water being forced over filaments, so do not work in air.

34
Q

How do humans breathe in?

A

The ribs are moved up and out and the diaphragm is moved downwards, causing the chest volume to increase and the pressure to decrease. The higher outside pressure causes air to enter the lungs.

35
Q

How do humans breathe out?

A

The intercostal muscles and diaphragm relax, causing the ribs to move down and inwards and the diaphragm to curve upwards. The chest volume therefore decreases, which increases the pressure, forcing the air out of the lungs.

36
Q

The total lung capacity consists of:

A
  • tidal air, which is the amount of air normally breathed in and out while at rest
  • vital capacity, which is the maximum amount of air which can be exchanged
  • residual air, which is the amount of air which cannot be forced out of the lungs
37
Q

Where does diffusion of gases take place in the lungs and why?

A

Exchange of gases takes place by diffusion between the alveoli (bulges of air sacs) and the air in the air sacs. Diffusion occurs because the oxygen concentration in the air is higher than in the deoxygenated blood capillaries around the alveoli.

38
Q

How are exchange surfaces in the lungs adapted for efficient gas exchange?

A

They have a large surface area and a good blood supply. They are permeable, moist and only one cell thick.

39
Q

What can readings from a spirometer do?

A

Readings from a spirometer are a measure of different lung capacities and the rate of air flow. They can be used to help diagnose lung diseases.

40
Q

What is asbestosis?

A

An industrial disease resulting from breathing in asbestos fibres. The fibres cause inflammation and scarring of lung tissue, reducing gaseous exchange.

41
Q

What happens in the inherited condition cystic fibrosis?

A

Too much mucus is produced in the bronchioles causing breathing difficulties.

42
Q

What are the symptoms of asthma?

A

Wheezing, a right chest and difficulty in breathing. Inhalers can be used to relieve the symptoms

43
Q

In humans, air must go in and out of the same structures. What does this mean?

A

This means that chemical particles such as tars (from cigarettes) and asbestos fibres can become trapped in air sacs.

44
Q

What happens during an asthma attack?

A

The lining of airways becomes inflamed, mucus and fluid build up in airways and the muscles around the bronchioles contract, narrowing the airways.

45
Q

Why is physical digestion important?

A
  • it allows the food to pass more easily through the digestive system
  • it prepares the food for chemical digestion by giving it a larger surface area
46
Q

Where is starch broken down?

A

In the mouth, where carbohydrase breaks down starch to sugar

47
Q

Where is protein broken down?

A

In the stomach, where protease breaks down protein to amino acids

48
Q

Where is fat broken down?

A

In the small intestine, where lipase breaks down fat into fatty acids and glycerol

49
Q

What are the two steps in the chemical breakdown of starch?

A
  • breakdown of starch (many linked units) to maltose (two linked units)
  • breakdown of maltose to glucose (one unit)
50
Q

What different pH’s do different digestive enzymes require?

A

Protease enzymes, such as pepsin the stomach, require a low pH (acidic) while other protease enzymes in the mouth and small intestine require a high pH (alkaline). Those in the mouth require a slightly acid/neutral pH.

51
Q

What does bile do and where is it stored?

A

The gall bladder stores bike. Bile is released into the small intestine to emulsify fats, increasing their surface area for efficient digestion.

52
Q

Why do food molecules have to be small and soluble?

A

Food molecules need to be able to pass through the walls of the small intestine and dissolve in the blood or lymph. This means that have to be small and soluble.

53
Q

How does glucose and amino acids get into the blood stream?

A

The digested carbohydrates and protein molecules (glucose and amino acids) are soluble. They diffuse through the walls of the small intestine and into the blood.

54
Q

What do digested fat molecules (fatty acid) do as they are not soluble in water?

A

The digested fat molecules (fatty acids) are not soluble in water or plasma, so would block up blood vessels. They diffuse through the walls of the small intestine and into the lymph.

55
Q

The small intestine is adapted for efficient absorption of food by having an extensive system of blood capillaries and an extensive lymphatic system of lacteals, which contain lymph. The small intestine also has a large surface area, created by:

A
  • many villi in the walls of the small intestine

- many microvilli (projections) from the walls of the villi

56
Q

Excess and unwanted amino acids are broken down in the liver, forming urea. Which is taken…?

A

In the blood to the kidneys

57
Q

What happens to blood containing waste once it has entered the kidney?

A

Blood containing waste such as urea enters each kidney by the renal artery. Blood without waste leaves by the renal vein. Each kidney has an outer cortex and an inner medulla. Waste removed from the kidney leaves through the uterus as urine.

58
Q

The blood flows through the kidneys under high pressure, what does this mean?

A

The blood flows through the kidneys under high pressure so filtration to remove washes also takes place under high pressure. Useful materials such as water, glucose and salt are reabsorbed back into the blood.

59
Q

Each kidney has millions of microscopic kidney tubules (nephrons) where filtration takes place to form urine. Each nephron has:

A
  • a network of capillaries (the glomerulus) surrounded by a capsule: this forms a filtration unit
  • a region where some materials such as glucose are selectively reabsorbed
  • a region where reabsorption of some salt and water takes place (the amount depends on body demands)
60
Q

When is a dialysis machine used and how does it work?

A

A dialysis machine is used when someone has kidney failure. The machine has many tubes containing blood, surrounded by a liquid. The machine acts as an artificial kidney an removes urea from the blood. As urea molecules are small they diffuse though the membrane. A dialysis machine also uses different sizes of tubes, so it slightly increases pressure during diffusion.

61
Q

What does the dialysis fluid contain and why?

A

The dialysis fluid contains sodium salts, so it is the same or slightly lower than the desired blood concentration. This maintains the sodium levels in the blood.

62
Q

The pituitary gland produces the anti-diuretic hormone (ADH) which controls the concentration of urea by:

A
  • increasing the permeability of kidney tubules so that more water is reabsorbed
  • using a negative feedback mechanism to control ADH production
63
Q

How would drinking a large quantity of water affect urine concentration?

A

After drinking a large quantity of water, the quantity of urine produced increases and the urine concentration decreases.

64
Q

How would hot conditions or doing strenuous exercise affect the quantity of urine?

A

During strenuous exercise or in hot conditions the body produces more sweat to cool down, so the quantity of urine produced decreases and the urine concentration increases.

65
Q

What does an increase of carbon dioxide in the body trigger?

A

The body is more sensitive to the level of carbon dioxide than to that of oxygen. An increase in carbon dioxide in the blood is detected by receptors in the carotid artery. Nerve impulses inform the brain, which causes the rate of breathing to increase to remove more carbon dioxide via the lungs

66
Q

What are four sex hormones and their role in the menstrual cycle?

A
  • FSH (follicle stimulating hormone) stimulates an egg to develop in an ovary
  • LH (luteinising hormone) controls ovulation (egg release)
  • progesterone maintains the uterus wall
  • oestrogen repairs the uterus wall
67
Q

What controls the level of sex hormones in the menstrual cycle?

A

Negative feedback mechanisms (which restore the situation after change) control the levels of the sex hormones in the menstrual cycle. The cycle is triggered by the receptors in the hypothalamus.

68
Q

What happens during the menstrual cycle to sex hormones?

A

If fertilisation does not occur, the levels of oestrogen and progesterone decrease.

When oestrogen and progesterone levels are low, menstruation occurs

A message is sent to the hypothalamus that hormone levels are again low. This cycle starts to begin again.

If an egg is fertilised, the levels of progesterone remain high and so no FSH is produced, so no more eggs develop and the uterus lining does not break down

69
Q

How do contraceptives control fertilisation?

A

Artificial sex hormones prevent ovulation by making the body think it is pregnant and this inhibits FSH release. Eggs in the ovary are therefore not stimulated to develop.

70
Q

Give six methods of treating infertility.

A

1) artificial insemination, where sperm is inserted into the vagina by syringe
2) using FSH to stimulate egg development
3) egg donation, when an egg is donated from another female, then fertilised and placed inside the uterus
4) surrogacy, where a fertilised egg is placed inside a surrogate mother
5) an ovary transplant from another female
6) IVF, in vitro fertilisation when an egg is fertilised by sperm outside the body

71
Q

A developing foetus can be checked to see if there are any abnormalities. Checking can be done by:

(What issues do these tests raise?)

A
  • amniocentesis (extracting and testing cells in the amniotic fluid)
  • chromosomal analysis (using a blood test to check for any chromosome abnormalities)

Using techniques like this raise ethical issues: whether it is right to interfere with a natural process and whether an unborn foetus has the right to live. The techniques also carry a small risk of causing the expulsion of the foetus.

72
Q

What can increase growth?

A

A balanced diet (containing calcium, phosphorus, vitamin D and proteins) and regular exercise can increase growth.

73
Q

What are extremes of height caused by?

A

Hormone imbalance or by genes.

The human growth hormone is produced by the pituitary gland and it stimulates general growth, especially in long bones.

74
Q

Why has life expectancy increased in recent times?

A
  • fewer deaths from industrial diseases
  • better housing, so there are fewer cases of diseases such as tuberculosis
  • a healthier diet and lifestyle
  • advances in modern medicine, such an antibiotics and transplants
75
Q

What are the consequences of a longer life expectancy?

A

A bigger burden on health services and pension funds.

76
Q

What are the problems involved with organ donation?

A

The supply of donated organs is limited by a shortage of donors and also by restrictions of use due to the necessity of tissue matches as well as those of size and age.

Organ donation raises ethical issues to do with human rights, the acceptance of surgery on a dead body and the fact that a person’s death has been necessary to supply the donor organ.

Transplants are at risk of being rejected by the recipients body and so need life long immuno-suppressive drugs which can lead to the body not being able to protect itself from micro organisms

77
Q

How can some of the problems of organ donation be solved?

A

Using mechanical replacements. However, these have other problems such as dependence on power supply, the properties of materials used, their large size and body reactions to foreign materials.

Some countries have an opt out system which assumes that organs can be donated without asking permission. Some people say this goes against human rights.

Biology (3 decks)

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