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Biology > Topic 7- Homeostasis > Flashcards

Topic 7- Homeostasis Flashcards

1
Q

What is the hormonal system?

A

The Collections of glands in the body that release hormones.

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2
Q

What is homeostasis?

A

The constant maintenance of internal conditions to maintain optimal conditions for cellular reactions. E.g core temperature, pH.

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3
Q

What are hormones?

A

They are chemical messengers, they take more time to get around the body than electrical messengers. They are transported by the blood and carried to their target organs.

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4
Q

Define metabolic rate?

A

The rate at which the energy stirred in your food is transferred by all the reactions that take place in your body to keep you alive.

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5
Q

Why do chemical messengers, such as hormones take more time to travel around the body and work than electrical messengers, such as neurones?

A

Hormones travel in the blood which therefore takes longer. Neurones travel using impulses.

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6
Q

Give some examples of endocrine glands:

A
  • Pituitary gland
  • adrenals
  • ovaries
  • tested
  • pancreas.
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7
Q

What is an endocrine gland?

A

An organ that makes and released hormones into the blood.

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8
Q

Where is the pituitary gland located and what hormones does it create and release?

A

Located in brain underneath lymphocytes. Releases many hormones:

  • FSH (Follicle Stimulating Hormone)
  • LH (Luteinising Hormone)
  • ACTH
  • Growth hormones
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9
Q

Where is the thyroid gland located, what does it do and what hormones does it release?

A

It releases the hormone thyroxine and is responsible for controlling metabolism. It is located just below the throat.

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10
Q

What hormones do ovaries release?

A

They release the sex hormone oestrogen and progesterone. It is responsible for growth characteristics (puberty).

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11
Q

Where is the adrenalin gland located and what hormone does it release?

A

Located in top of the kidneys. Releases the hormone adrenalin. Responsible for the ‘flight or fight’ mechanism associated with danger.

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12
Q

What hormone does the tested release?

A

Releases the sex hormone testosterone. Responsible fo growth characteristics in makes e.g puberty.

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13
Q

What hormone does the pancreas release and where is it located?

A

Located behind the stomach. Contains cells that release insulin and glucagon. Helps keep blood sugar levels safe.

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14
Q

What is meant by target organ?

A

An organ affected by a specific hormone.

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15
Q

How will a hormone affect its target organ?

A

It will affect the organ by changing what the organ is doing. E.g growth hormones stimulate cells in muscles and bones to divide.l it also stimulates the digestive system to absorb more calcium ions, used to make bones strong.

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16
Q

How is the resting metabolic rate measured?

A

Measured with the body at rest, in a warm room longer after the person has had their last meal.

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17
Q

What hormone affects metabolic rate?

A

Thyroxin, released by the thyroid gland.

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18
Q

What does the hormone thyroxine do?

A
  • it is taken into and affects many different types of cells.
  • it causes heart cells to contract more quickly and strongly.
  • increases rate at which proteins and carbohydrates are broken down inside cells.
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19
Q

Define the term negative feedback.

A

A control mechanism that reacts to a change in condition, such as temperature, by trying to bring the condition back to a normal level.

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20
Q

Give an example of endocrine gland which is a target organ for another hormone:

A

The sex hormone oestrogen and testosterone are released in the reproductive system, they stimulate the release of growth hormones. The release of sex hormones increases during puberty and this why there is an increase in growth rate at this time.

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21
Q

What is the amount of they rosins produced controlled by?

A

Hormones released by 2 other glands:

  • hypothalamus (which releases TRH)
  • pituitary (which releases TSH)

The levels of each of these hormones stimulates the amount of other hormones in this chain being produced. It is also an ex plane of negative feed back.

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22
Q

In what situations are a lot of adrenalin released and how?

A

Normal levels of adrenalin are quite low. However, in a frightening or exciting situation an increase in impulses from neurones reaching the adrenal glands from the spinal chord triggers the release of large amounts of adrenalin in the blood.

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23
Q

What is one of the target organs of adrenalin and what does it do at this target organ?

A

The liver is one of the target organs of adrenalin. Here it causes the breakdown of storage substances called glycogen. Glycogen is a polymer made from glucose molecules. When glycogen is broken down glucose molecules can be released into the blood providing additional glucose for respiration. (This gives energy for ‘fight or flight’)

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24
Q

What is glucagon?

A

A polymer made of glucose molecules.

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25
Q

What are the target organs of adrenalin?

A
  • liver
  • heart
  • blood vessels
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26
Q

How does adrenalin affect the heart?

A

Heart muscle cells contract:

  • more rapidly, which increases the heart rate.
  • more strongly, which increases blood pressure.
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27
Q

How does adrenalin affect blood vessels?

A

It has 2 affects depending on the type of blood vessel:

  • diameter blood vessels leading to muscles widens, which increases blood flow to muscles.
  • diameter of blood vessels leading to other organs narrows, which reduced blood flow to those organs and increases blood pressure.
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28
Q

How does adrenalin affect the liver?

A

Liver cells turn glycogen into glucose and release into the blood which increases blood sugar concentration.

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29
Q

What is the menstrual cycle?

A

A cycle of changes in a women’s reproductive system and takes about 28 days. The cycle continues from puberty (around 12 years old) to menopause (around 50 years old) and prepares a woman’s body for the fertilisation if an egg cell, leading to pregnancy.

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30
Q

What is menstruation?

A

This occurs in day 1 of the menstruated cycle. It is the break down and loss of lining of the uterus along Sotheby’s the unfertilised egg. This causes a period.

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31
Q

What is ovulation and when does it occur?

A

Ovulation occurs when the ovaries release an egg?

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32
Q

What happens in days 1-5 of the menstrual cycle?

A

Menstruation happens during this time. The uterus lining breaks down and is lost with unfertilised egg.

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33
Q

What happens during days 6-12 of the menstrual cycle?

A

When menstruation ends the uterus lining starts to thicken again.

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34
Q

What happens during days 13-15 of the menstrual cycle?

A

Ovulation- when the ovaries release an egg cell.

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35
Q

What happens during days 16-28 of the menstrual cycle?

A

Fertilisation leading to pregnancy is most likely at this stage. The uterus lining continues to thicken. The egg cell travels along the oviduct to the uterus. The cycle then starts again.

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36
Q

What is the menstrual cycle controlled by?

A

The cycle is controlled by the sex hormones oestrogen and progesterone.

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37
Q

What is contraception?

A

The prevention of fertilisation.

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38
Q

Give 3 types of contraception methods, how they work and how effective they are:

A

Condom: placed over penis and prevents sperm enter in vagina. It has a 98% success rate in preventing fertilisation.

Diaphragm/cap: placed over the cervix (entrance to the uterus) prevents speed in the vagina entering the uterus. It has a 92%-96% success rate in preventing fertilisation.

Hormone pill or implant placed under skin: release hormones to prevent ovulation and thicken mucus at the cervix, making it difficult for sperm cells to pass through.

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39
Q

What controls the release of the hormones FSH and LH from the pituitary gland?

A

The release of these hormones is controlled by the concentration of oestrogen (which increases as the egg follicle matures) and progesterone (which is released after ovulation when the egg follicle becomes a structure called the corpus luteum).

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40
Q

What is Assisted Reproductive Technology (ART)?

A

This uses hormones and other techniques to increase the chance if pregnancy. It is used to help some couples who struggle to have a child become pregnant.

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41
Q

What is Clomifene therapy and how is it used?

A

This is useful for women who rarely or never release and egg cell during the menstrual cycles. Clomifene is a drug that helps to increase the concentration of FSH AND LH in the blood.

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42
Q

What is IVF?

A

In Vitro Fertilisation. This is another ART technique. This can overcome problems such as blocked oviducts in the woman, or of the man produced very few healthy sperm cells. Any healthy embryos not used in the first attempt at pregnancy may be frozen and stored for use of another time.

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43
Q

What are the steps in carrying out IVF?

A

1) Egg follicle maturation is stimulated by hormones.
2) Egg cells released by many follicles and taken from ovary.
3) sperm cells taken from man.
4) eggs and sperm combined to allow fertilisation.
5) one or two healthy embryos placed in uterus.

44
Q

What can urine tests be used to test for?

A

This a simple of way of testing for pregnancy or for diseases, such as diabetes.

45
Q

How is glucose formed in the gut during digestion?

A

During digestion in the gut, glucose is released from carbohydrates in our food. Glucose is easily absorbed from the small intestine into the blood and then into cells, where it is broken down during respiration.

46
Q

Why might glucose reach a high concentration in the blood and how is this dangerous?

A

It takes times for cells to take in glucose released by digestion, so there is a risk that glucose may reach a very high level in the blood. This can be dangerous because it can damage organs. However, in most people this does not happen, because blood glucose concentration is carefully controlled.

47
Q

What is the role of insulin?

A

As blood glucose rises, it stimulates certain cells in the pancreas to release the hormone insulin. Insulin causes cells in the liver and other organs to take in glucose, which causes a fall in blood glucose concentrations.

48
Q

What are the steps involving glucose to be absorbed by cells?

A

1-glucose is absorbed from the small intestine after the digestion of food.
2-blood glucose concentration rises.
3-pancreas responds to high blood glucose levels by releasing insulin.
4-insulin causes the liver, muscles and other cells to take in glucose and change it to glycogen for storage.
5-blood concentration falls to normals levels.

49
Q

How does the blood glucose concentration link to the amount insulin releasing cells in the pancreas release insulin?

A

As blood glucose concentration falls, the insulin releasing cells in the pancreas release less and less insulin. If the blood glucose levels falls below a certain level, the cell stops releasing insulin altogether.

50
Q

What is the role of the hormone glycogen and where is it located?

A

Glucagon hormones are released by the pancreas. Their target organ is the liver. If blood glucose concentration falls too low pancreatic cells release glucagon, which causes the liver to convert glycogen back to glucose, which is released into the blood. As blood glucose concentrations increases, the amount of glucagon released from the pancreas falls.

51
Q

Why is homeostasis important?

A 
All the processes involved in homeostasis help to prevent damage to the body as internal and external conditions change.
Examples of homeostasis include:
-blood glucose concentration control
-temperature control
-control of water content
52
Q

When a person has type 1 diabetes what is different to how their body produces insulin to a normal person?

A

Pancreatic cells that should produce insulin do not. This is because the cells have been destroyed by the bodies immune system these people have type 1 diabetes and it means they cannot control rising blood glucose concentration.

53
Q

Why is a urine test the first test to test for type 1 diabetes?

A

When blood glucose concentration is too high and some glucose can be detected in the urine. This is why it is often the first test for type 1 diabetes.

54
Q

What happens when people with type 1 diabetes inject themselves with insulin?

A

They injected themselves with insulin into a fat layer below the skin, where it can enter the blood causing blood glucose concentrations to fall.

55
Q

What causes type 2 diabetes?

A

This is caused by insulin releasing cells not pricing enough insulin, or by target organs not responding properly to the hormone.

56
Q

How can type to diabetes be treated?

A
  • for some, just eating healthily and keeping the amount of sugar in their diet low can control their diabetes.
  • being physically active can also help because it takes glucose out of the blood.
  • people with severe type 2 may be given medicines to reduce the amount of glucose that the liver releases into the blood, or to increase the sensitivity of the cells in target organs that respond to insulin.
57
Q

Why are people with type 1 diabetes and type 2 diabetes treated differently?

A

People with type to may still have some response to insulin. People with type 1 mostly have no response.

58
Q

can you explain the correlation between an increase in type 2 diabetes and an increase in the average body mass?

A

The two factors have a strong positive correlation. As the average body mass increases so does the amount of people being diagnosed with type 2 diabetes.

The more fat someone had in their body the more likely they are to get type 2 diabetes. This is because they have a higher blood glucose concentration consistently.

59
Q

Why do scientists use BMI?

A

Taller people have a larger mass that shorter people, so scientists need to take height into account and work out weather a person has the right mass for their height.

60
Q

What is the equation to work out BMI?

A

BMI = mass (kg)/height(m)sq

61
Q

What BMI is considered overweight and underweight?

A

Underweight: below 18.5
Normal: 18.5-24.9
Overweight: 25.0-29.9
Obese= >30.0

62
Q

What is the waist:hip ratio and how does it work?

A

This is calculated by the waist measurement divided by the hip measurement. As people increase in mass they tend to develop more fat in their waist compared to their hips. This increases their waist to hip ratio and also correlates with the risk of developing type 2 diabetes.

63
Q

What are the disadvantages of using BMI to calculate weather someone is overweight?

A

BMI does not take into account body muscle. Someone may be very muscly but this many not mean they are fat or over weight.
It also doesn’t take into account where body fat is distributed.

64
Q

What is the normal temperature of major organs (e.g heart, liver, brain) of the human body?

A

37°c although this varies slightly between people. A temperature above 38°c is a fever and below 36°c causes hypothermia.

65
Q

What is the target organ of insulin?

A

Liver

66
Q

What is the treatment of type 1 diabetes?

A

Insulin injections.

67
Q

Why are both fevers and hypothermia dangerous to the human body?

A

Because they affect how well enzymes work in the body.

68
Q

What is thermoregulation?

A

The control body temperature, which keeps the temperature of major organs close to 37°c most of the time.

69
Q

What is the difference between causes of type 1 and type 2 diabetes?

A

Cause of type 1: this is when the pancreas is not able to produce enough insulin. It is a gene mutation that can be passes on.

Cause of type 2 diabetes: this is when cells become resistant to insulin. However, insulin is still being produced.

70
Q

What is the hypothalamus and how does it detect a temperature change?

A

A small part of the brain that constantly monitors temperature. It receives information from temperature receptors in the dermis of the skin. Receptors inside the hypothalamus detect temperature changes in the brain and in the blood.

71
Q

What changes does the hypothalamus cause when it detects blood or brain temperatures falling below 37°c?

A
  • shivering, when muscles start to contract and relax rapidly. Some of the energy released from the cell respiration for shivering warms you up.
  • contraction of erector muscles in the dermis of the skin causes body hairs to stand upright. In humans this has little effect, but in other animals it traps air next to the skin for insulation.
  • reduction of blood flow near the skin keeps warm blood deeper inside the body. This reduces the rate of transfer of energy to the air by heating.
72
Q

What is the dermis?

A

This is a layer below the epidermis of the skin, which contains temperature receptors, sweat glands and erector muscles.

73
Q

What is vasoconstriction and how does it help to keep the body warm?

A

This is when it is cold, the hypothalamus sends nerve impulses to small arteries deep in the skin, causing them to narrow. This reduces blood flow in the capillaries near the surface of the skin and helps to reduce energy transfer to the surroundings.

74
Q

What is vasodilation and how does it help control body temperature?

A

When the body is hot, the hypothalamus causes the small arteries to wide-vasodilation. This increases blood flow through skin capillaries, bringing warm blood near to the surface of the skin and increasing energy transfer to the surroundings.

75
Q

What is the control of temperature in the body and example of and why is this important?

A

This is an example of negative feedback. This helps keeps conditions in the body under control and at the right level.

76
Q

What is osmoregulation?

A

Is the control of the balance of water and mineral salts.

77
Q

Why is osmoregulation important?

A

If the balance of water and mineral salts is wrong, then cells may take in or lose too much water by osmosis. This can damage cells because water in the cells allows all the molecules in the cells reaction to move around. Water is also needed to maintain the shape of the cell.

78
Q

What is the function of the urinary system?

A

To remove excess amounts of some products from the blood, including water and mineral salts as well as waste products like urea.

79
Q

What is urea?

A

This is a waste product. It is produced in liver cells from the breakdown of amino acids that are in greater amounts than needed. The urea passes into the blood and is carried into the kidneys.

80
Q

How is the structure from the urinary system adapted?

A
  • the renal arteries carries blood from the body to the kidneys.
  • the kidneys remove substances from the blood and make urine.
  • the renal veins carry blood with wastes removed back to the body.
  • the uterus carry urine from the kidneys to the bladder.
  • the bladder stores urine.
  • a muscle keeps the exit from the bladder closed until a person decides to urinate.
81
Q

What is kidney failure?

A

When both kidneys stop working properly. The human body can manage with only one healthy kidney.

82
Q

Why would a persons life be in danger if they had kidney failure?

A

Because waste substances increase in concentration in the blood.

83
Q

What are the two treatments to kidney failure?

A

Dialysis- process used to clean blood and remove urea for people with kidney failure. It involves the exchange if substances between blood and dialysis fluid across a partially permeable membrane.

Transplant- when a matching kidney donor is found and the kidney is transplanted into the body of someone suffering from kidney failure and attached to their blood system.

84
Q

What is the kidney?

A

The organ that removes urea, excess water and other substances from the blood to form urine.

85
Q

What are the advantages and disadvantages of a transplant?

A

Advantages:

  • patients can lead a normal life without having to watch what they eat and drink.
  • overall it’s cheaper for the NHS.

Disadvantages:

  • kidney only lasts 8-9 years on average.
  • must take immune suppressant drugs to reduce chance if body rejecting kidney. This increases the risk of infection.
  • operations carry risks. Especially for weak patients.
  • shortage of organ donors.
86
Q

What are the advantages and disadvantages of dialysis?

A

Advantages:

  • available to all kidney patients (no shortage)
  • no need for immune suppressant drugs.

Disadvantages:

  • patients must limit their salt and protein intake between dialysis sessions.
  • regular dialysis sessions-impacts on patients life.
  • expensive for the NHS.
87
Q

What is renal damage failure?

A
  • kidneys not being able to filter the blood effectively.
  • plasma not properly reabsorbed.
  • proteins and cells as a result pass through bowman’s capsule so may be present in urine.
88
Q

How many times does dialysis need to be done a week and how long does each round of treatment take?

A

3 times a week. Each treatment is 3 hours.

89
Q

Why are organ donors not suitable for all people?

A

Some people may reject their organ donor. It also involves servers hours of surgery and someones body who is very old may not be able to handle this.

90
Q

How can your body reject a transplanted kidney?

A

Kidney cells, like all cells, have antigens on them. Cells in the immune system recognise and attack antigens they don’t recognise. This can cause rejection of the donated kidney. This why the antigens in the donated organ must therefore be matched to those of the patients cell.

91
Q

What does the quantity and colour of your urine relate to?

A

The colour of your urine varies at different types of the day and the quantity of the urine you produce relates to how much you have drunk or how active you have been. These variations are due to the way your kidney works.

92
Q

Where is urine made?

A

In the nephron, located in the kidney.

93
Q

What is the nephron?

A

Each kidney contain thousands of tiny microscopic tubes called nephrons. This is where the urine is made in a series of stages.

94
Q

How are the glomerulus and bowman’s capsule adapted for their function?

A

Each bowman’s capsule cell forms a vast series of ‘fingers’ with spaces between them. Small molecules can filter through these spaces from the leaky capillaries below.

The capillary cell’s in the glomerulus and the cells that form that forms the bowman’s capsule have spaces between them. This makes both the glomerulus and the capsule leaky.

95
Q

What are the stages that create urine in the kidney?

A

1-blood flows through a network of capillaries called a glomerulus, which runs inside the Bowman’s capsule of each nephron.

2-the Bowman’s capsule and glomerulus are adapted to let very small molecules, such as water, glucose and urea through into the nephron. Large molecules such as proteins and blood cells stay in the blood. This process is called filtration.

3-the filtration fluid flows along inside the nephron. Selective reabsorption of useful substances that the body need occur here. This includes glucose and some mineral ions. These substances are pumped through proteins in cell membranes in the first convoluted tubule of the nephron by active transport. Normally no glucose is left in the urine.

4-water is reabsorbed by osmosis, depending on how much the body needs. This happens in the loop of Henley and collecting duct.

5-at the end of the nephron the remaining fluids flow into the ureter. The fluid contain excess water that the body does not need, plus urea and other substances which can now be called urine.

96
Q

How is the nephron adapted for reabsorption?

A
  • there is a large surface area of contact between the nephron and capillaries.
  • the cell membrane of the cells lining the first convoluted tubule has tiny folds called microvilli. This increases the surface area:volume ration of the cells.
  • cells that have protein pumps in their membrane have many mitochondria in order to carry out active transport.
97
Q

Apart from getting rid of urea what else to the kidneys do?

A

They help to control the water content of the blood. When the pituitary gland detects there is too little water in the blood it releases the hormone ADH (Antidiuretic hormone).

98
Q

What does the hormone ADH do?

A

It changes the permeability if the collecting duct in nephrons and increases the concentration of urine. When there is plenty of water in the body it stop releasing ADH.

99
Q

Why is osmoregulation important and what would happen if you had too much water in you blood?

A

Osmoregulation is important because if you have too much water your blood, your red blood cells will swell an burst. If you don’t have enough your cells shrink.

100
Q

What is the primary role of your kidney?

A
  • filter the substances out of your blood, such as urea.

- balance the amount of water and salt in your blood.

101
Q

What detects changes in the concentration of water in the blood?

A

The hypothalamus located in the brain detects changes.

102
Q

What is the role of the glomerulus when creating urine?

A
  • blood flows through the capillary network.
  • this runs inside the Bowman’s capsule.
  • blood is squeezed through allowing substances such as glucose, water and urea through.
  • proteins and blood cells are too big to be pushed through. This process is called filtration.
103
Q

What is the role of the first convoluted tubule when creating urine?

A
  • the filtrate moves here.
  • selective reabsorption takes place.
  • Glucose and some mineral ions move through here by active transport.
104
Q

What is the role of the loop of Henle when creating urine?

A
  • water is absorbed here by osmosis

- the amount of water absorbed depends on how much the body needs.

105
Q

What is the role of the collecting duct when creating urine?

A
  • water is also reabsorbed in the collecting duct (tubule).

- this depends on how thirsty or not you are.

106
Q

What causes type 1 diabetes and how is it treated?

A

In type 1 the pancreas does not produce enough insulin. Glucose levels may rise too high.
Type 1 diabetes is usually treated with insulin injections.

Biology (10 decks)

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