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All Topics GCSE Biology Triple > Topic 7- Homeostasis > Flashcards

Topic 7- Homeostasis Flashcards

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1
Q

What is the the purpose of the endocrine system ?

A

The endocrine system coordinates the body’s response to changes in the environment using chemical messengers (hormones).

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2
Q

How are hormones released into the bloodstream ?

A

Glands

Hormones are released by glands into the bloodstream, where they travel to target organs

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3
Q

What are the glands in the human body ?

A 
Pituitary gland 
Pancreas 
Testes
Thyroid gland 
Ovaries 
Adrenal gland
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4
Q

Where is the pituitary gland ?

A

This is the main endocrine gland or “master gland”.

It is found in the brain and is linked to the hypothalamus (part of the brain that receives signals from receptors).

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5
Q

What is the role of the pituitary gland ?

A

The pituitary gland releases hormones in response to changes detected by the hypothalamus.
Lots of these hormones trigger other glands to release more hormones.

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6
Q

What is the role of the pancreas ?

A

The pancreas produces insulin and glucagon, both of which are involved in regulating blood glucose levels

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7
Q

What is the role of the testes ?

A

The testes produce testosterone, which controls puberty and sperm production.

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8
Q

Where is the thyroid gland found ?

A

This gland is in our neck

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9
Q

What is the role of the thyroid gland ?

A

releases thyroxine

Thyroxine regulates our metabolism, heart rate and temperature

It increases the basal (resting) metabolic rate.

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10
Q

What are the roles of the ovaries ?

A

The ovaries produce oestrogen, which controls puberty and is one of the main hormones in the regulation of the menstrual cycle.

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11
Q

Where are the adrenal glands found ?

A

The two adrenal glands are situated above each kidney.

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12
Q

What is the role of the adrenal glands ?

A

They produce adrenaline, which triggers the ‘fight or flight’ response when an organism is presented with a dangerous situation.

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13
Q

Why is the pituitary gland often called the “master gland” ?

A

The pituitary gland releases hormones in response to changes detected by the hypothalamus.
Lots of these hormones trigger other glands to release more hormones.

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14
Q

How is the endocrine system different from the central nervous system?

A

The endocrine system coordinates the body’s response to environmental changes using chemical messengers (hormones).
The central nervous system uses electrical impulses.

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15
Q

In both the nervous and endocrine system what is the basic response order ?

A

Both systems follow the same basic response order:
Receptor cells (detect changes in the environment)
Coordination centres (process information)
Effectors (muscles or glands that bring about a response).

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16
Q

How does the nervous system trigger a response compared to the endocrine system?

A

Triggers rapid response.
Uses electrical signals that are carried by neurones.
Response is very short.
Acts on a very precise part of the body.

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17
Q

How does the endocrine system trigger a response compared to the nervous system?

A

Triggers a slower response.
Uses chemical messengers that are carried by blood.
Response can be long-lasting.
Can act on large areas of the body

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18
Q

What are hormones ?

A

Chemical messages

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19
Q

What is the main hormone released by the thyroid gland ?

A

Thyroxine

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20
Q

How is thyroxine regulated ?

A

A Negative feedback loop

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21
Q

When the concentration of thyroid hormones, such as thyroxine, in the blood is low, the hypothalamus (in the brain) produces what ?

A

TRH (thyrotropin-releasing hormone).

This causes the pituitary to release thyroid-stimulating hormone (TSH), which stimulates the secretion of thyroxine by the thyroid gland.

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22
Q

Once thyroxine levels have returned to ‘normal’ or above normal what happens to TRH ?

A

TRH secretion is reduced. This reduces TSH and thyroxin levels.

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23
Q

What is a hormone secreted (discharged) by the adrenal glands ?

A

Adrenaline is a hormone secreted (discharged) by the adrenal glands.

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24
Q

In times of fear or stress, what does adrenaline do ?

A

the so-called ‘fight or flight’ response is activated, preparing the body to move and think quickly in response to danger

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25
Q

What converts stored glycogen back into glucose, raising the blood sugar levels ?

A

The liver

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26
Q

Why does adrenaline enlarge (make bigger) the air passages of the lungs and alter (changes) metabolism ?

A

to boost the delivery of oxygen and glucose to the brain and the muscles.

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27
Q

How does Adrenaline increases heart rate and blood pressure ?

A

(by vasoconstriction, which is when blood vessels constrict).

This means that there is an increase in blood flow around the body, specifically to the muscle cells.

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28
Q

What are Features that appear during puberty called ?

A

secondary sex characteristics

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29
Q

Once a female reaches puberty what changes occur ?

A

The amount of the hormone oestrogen rises and triggers the menstrual cycle.

Underarm and pubic hair grow.

Breasts enlarge.

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30
Q

Once males reach puberty what changes occur ?

A

The amount of the hormone testosterone rises. This stimulates sperm production.

Underarm, facial and pubic hair grow.

Voice deepens.

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31
Q

Name three regions of the male body that experience hair growth after puberty:

A

Underarm, facial and pubic hair grow.

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32
Q

In males, puberty increases the amount of what hormone ?

A

the hormone testosterone

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33
Q

At puberty for men the hormone testosterone increases, what does this do ?

A

stimulating the production of sperm.

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34
Q

In females, at puberty the amount of what hormone increases ?

A

oestrogen.

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35
Q

In puberty the female hormone oestrogen increases, what does this do ?

A

triggers the menstrual cycle

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36
Q

What is the time period between each menstral cycle ?

A

monthly cycle

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37
Q

What happens during the menstral cycle ?

A

the maturation (process of maturing) and release of an egg.

If sexual intercourse has occurred, this can result in pregnancy

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38
Q

The menstrual cycle can be divided into four stages depending on what ?

A

the levels of the hormones

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39
Q

The menstrual cycle is controlled by what four hormones from the endocrine system ?

A

Follicle Stimulating Hormone (FSH)
Oestrogen
Luteinising Hormone (LH)
Progesterone

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40
Q

A female is born with all of her eggs ready, but how many eggs will mature each month once the female reaches puberty ?

A

only one egg will mature each month once the female reaches puberty.

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41
Q

What is the order of the hormones being released of the menstral cycle ?

A
  1. FSH - FSH stands for Follicle Stimulating Hormone
  2. Oestrogen
  3. LH - LH stands for Luteinising Hormone
  4. Progesterone
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42
Q

In the menstral cycle what is the role of FSH ?

A

FSH stands for Follicle Stimulating Hormone.

It is released by the pituitary gland and causes an egg in the ovary to mature.

FSH also stimulates (encourages) the production of oestrogen

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43
Q

In the menstral cycle what is the role of oestrogen ?

A

Oestrogen is produced in the ovaries and causes the development of the thick, spongy uterus lining.

Oestrogen also stimulates the production of Luteinising Hormone (LH) and inhibits (stops) the production of FSH.

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44
Q

In the menstral cycle what is the role of LH (Luteinising Hormone) ?

A

LH is produced by the pituitary gland and stimulates the release of a mature egg on Day 14 of the menstrual cycle.

This release is called ovulation.

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45
Q

In the menstral cycle what is the role of progesterone ?

A

Progesterone is produced in the ovaries after ovulation.

It is responsible for maintaining the lining of the uterus during days 14-28.

When progesterone levels drop, this triggers the breakdown of the lining. This marks day 1 of the next menstrual cycle. Progesterone also inhibits (stops) the release of LH and FSH.

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46
Q

What are the stages of the menstral cycle ?

A

Stage 1 (days 1-4): The uterus lining breaks down, resulting in a ‘period’.

Stage 2 (days 4-14): The uterus lining starts to build up again into a thick, spongy layer full of blood vessels.

Stage 3 (day 14): Ovulation happens. This is when an egg is released from one of the ovaries.

Stage 4 (day 15-28): The uterus lining is maintained, which means that it is now ready for the arrival of a fertilised egg (which will eventually grow into a baby). If no fertilised egg is attached to the uterus lining, the lining breaks down and the cycle begins again.

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47
Q

On what day of the menstrual cycle does ovulation occur?

A

14

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48
Q

What is role of contraceptive pills ?

A

They reduce a woman’s fertility to reduce the likelihood of pregnancy

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49
Q

What are the two main types of contraceptive pill ?

A

Combined pill

Progesterone-only pill

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50
Q

What is the does the Combined pill do ?

A

Contains both oestrogen and progesterone.

By taking it every day, enough oestrogen builds up in the female body to inhibit the production of FSH so that no eggs mature.

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51
Q

What is the does the Progesterone-only pill do ?

A

Stimulates the production of thick, sticky mucus, which is very difficult for any sperm to penetrate.

Inhibits the release of FSH, so that eggs don’t mature.

Just as effective as the combined pill but with fewer side effects.

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52
Q

What contraceptives dont have to be taken daily ?

A

Contraceptive implant

Contraceptive injection

Contraceptive patch

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53
Q

What does the contraceptive implant do ?

A

The contraceptive implant, which can last for 3 years, is inserted under the skin (normally in an arm) and continuously releases a small amount of progesterone.

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54
Q

What does the Contraceptive injection do ?

A

The contraceptive injection contains progesterone and can last up to three months.

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55
Q

What does the contraceptive patch do ?

A

The woman places the small contraceptive patch onto the skin, which only has to be changed once a week.

This steadily releases progesterone.

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56
Q

Which hormone is released by the contraceptive patch, injection and implant?

A

Progesterone

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57
Q

What two contraceptives work by being insterted into a females body ?

A

Intrauterine devices (IUDs)

Diaphragms

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58
Q

What do Intrauterine devices (IUDs) do ?

A

This is also known as the coil.
They are small t-shaped devices that are inserted into the uterus.
They work by preventing implantation of an embryo (fertilised egg).
Some intrauterine devices also release progesterone.

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59
Q

What do diaphragms do ?

A

A diaphragm is a shallow plastic cup, which is inserted into the vagina prior to sexual intercourse and sits at the entrance to the uterus.
It is designed to prevent the sperm from reaching the egg.
It can also be covered in a spermicide to kill the sperm.

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60
Q

Condoms are effective in protecting against sexually transmitted infections (STIs), like what ?

A

such as chlamydia, gonorrhoea and HIV.

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61
Q

When are condoms used ?

A

Condoms can be worn by the male on his penis during sexual intercourse.

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62
Q

What do Condoms often contain ?

A

Condoms often contain a spermicide, which kills the sperm on release.

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63
Q

What is the role of condoms ?

A

Condoms prevent the sperm from entering the female during ejaculation

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64
Q

Some women prefer to use ‘natural methods’ of contraception.

What are these ?

A

Timing (monotring body temperature)

Abstinence

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65
Q

How does the ‘natural’ contraception method timing work ?

A

Since a female’s body temperature usually rises during ovulation, some women choose to avoid sexual intercourse on days when they know (or feel) that they are ovulating.

However, sperm can last up to six days inside the woman’s body, so this is not a very reliable or effective method of contraception.

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66
Q

How does the ‘natural’ contraception method Abstinence work ?

A

The only truly effective way (apart from sterilisation) to avoid pregnancy is abstinence.

This simply means that a couple chooses to not have sexual intercourse unless they are ready for a baby.

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67
Q

What is the only truly effective method of avoiding pregnancy?

A

Abstinence

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68
Q

How does a male undergo sterilisation ?

A

For a male, this involves having the sperm ducts (the tubes between the testes and the penis) cut so that the sperm are not released on ejaculation.

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69
Q

How does a female undergo sterilisation ?

A

For a female, this involves having the fallopian tubes (ducts which connect the ovaries to the uterus) cut so that an egg cannot reach the uterus.

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70
Q

What is Sterilisation ?

A

Sterilisation is a permanent procedure to remove any chance of getting pregnant

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71
Q

Some women do not have high enough levels of FSH to stimulate (lead to) the maturation of their eggs, what does this mean .

A

They are infertile

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72
Q

What two Modern reproductive technologies can help women that are infertile to give birth ?

A

Clomifene

In vitro fertilisation (IVF)

73
Q

What does In vitro fertilisation (IVF) do ?

A

FSH & LH are given to stimulate the growth of lots of eggs.

Eggs are collected before being fertilised in a dish in a laboratory. They are fertilised using sperm from the father.

These fertilised eggs grow into embryos and are implanted into the woman’s uterus.

Sometimes, two embryos are implanted to try to increase the chance of pregnancy.

74
Q

What does Clomifene do ?

A

Clomifene is a fertility drug that triggers ovulation by causing an increase in the release of FSH. This helps the follicle mature into an egg cell and increases the concentration of LH to cause ovulation.

75
Q

What does IVF stand for?

A

In vitro fertilisation

76
Q

How many hormones are given to the woman in an IVF treatment

A

2

FSH
LH

77
Q

What is the advantage of fertility treatments ?

A

is that they offer fresh hope to couples who are unable to conceive naturally

78
Q

What are the disadvantages of fertility treatments ?

A

Stress - It can place high levels of emotional and physical stress on patients and their families.

Multiple pregnancies - The treatments can result in multiple pregnancies (twins or triplets if more embryos are implanted).
This can put both the mother and the children at risk.

Expensive - Fertility treatments are not guaranteed to work and can be very expensive.
Their success rates are not that high and many attempts may be needed.

79
Q

An infertile woman has insufficient levels (doesn’t have enough) of which hormone?

A

FSH

80
Q

GnRH is a hormone released from the hypothalamus that controls the release of FSH and LH from the anterior pituitary gland.

High levels of oestrogen inhibit the release of GnRH. What is this an example of?

A

This is an example of a homeostatic negative feedback mechanism.
GnRH controls the release of FSH. FSH then controls then stimulates the release of oestrogen from the ovaries.
GnRH → FSH → oestrogen
As oestogen levels rise, oestrogen inhibits the release of GnRH.
Lower levels of GnRH mean less FSH is released.
Consequently, less oestrogen is released.
This is an example of a negative feedback mechanism.

81
Q

Oestrogen inhibits the release of FSH and GnRH. What is the benefit of this?

A

The benefit of oestrogen inhibiting both FSH and GnRH is that it allows very fine control of blood hormone levels and acts as a safety mechanism.
Fine control of oestrogen blood levels:
GnRH and FSH both cause oestrogen levels to rise.
High oestrogen levels can be dangerous.
For example, high oestrogen levels can promote blood clot formation.
As oestrogen inhibits both FSH and GnRH, it means blood oestrogen levels are tightly regulated.
There are two levels of control.
Safety Mechanism:
Oestrogen inhibiting the release of GnRH and FSH also acts as a safety mechanism. If the anterior pituitary gland stops responding to oestrogen (e.g. due to injury), oestrogen can still inhibit the release of GnRH from the hypothalamus

82
Q

Gonadotroph adenomas are a rare type of pituitary gland tumor. What are symptoms of an individual with a gonadotroph adenoma?

A

Weight loss
Headaches
Menstrual irregularity

83
Q

How do oestrogen and progesterone affect the female menstrual cycle?

A

Effect of oestrogen
Oestrogen inhibits the release of FSH.

Effect of progesterone
Progesterone inhibits the release of FSH and LH.

Effect of both oestrogen and progesterone
Both cause the lining of the uterus to increase in thickness.

84
Q

What does homeostasis describe

A

Homeostasis describes all of the processes that happen in a cell or organism to maintain (keep) conditions optimal.

85
Q

What does homeostatis need to respond too ?

A

This is needed to respond to changes in the internal and external environment

86
Q

Why must humans regulate our body’s internal conditions ?

A

Because humans are organisms that live in a changing environment

to make sure our enzymes and cells function well

87
Q

If conditions are not optimal what happens to our enzymes ?

A

If conditions are not optimal, then our enzymes can denature (change shape).

This reduces their ability to catalyse (speed-up) metabolic reactions (chemical reactions in organisms).

88
Q

If our internal conditions are not regulated, which of the following substances could denature?

A

Enzymes

89
Q

What internal conditions are regulated to make sure that enzymes and cells function well ?

A 
Water levels 
Urea concentration (in urine)
Internal body temperature
Carbon dioxide levels
Blood sugar levels
90
Q

What can happen if the body stops operating in optimal internal conditions?

A

Slower metabolic reactions

Enzymes denature

91
Q

What two responses do control systems ?

A

Control systems use both nervous and chemical responses

92
Q

What three parts are the control systems made up of ?

A

Receptors
Effectors
Coordination centres

93
Q

What is the role of receptors ?

A

Receptor cells detect changes in the environment

94
Q

What is the role of effectors ?

A

Effectors (muscles or glands) carry out responses to stimuli (events or things) that help to restore optimum levels.

95
Q

What is the role of coordination centres ?

A

Coordination centres receive and process information arriving from receptor cells.

96
Q

Negative feedback loop

A

J

97
Q

What is the optimum human body temperature?

A

37 degrees

98
Q

What do Receptors in the thermoregulatory centre of our brain (called the hypothalamus) monitor ?

A

monitor the internal body temperature as blood flows through the brain

99
Q

What do Receptors on the surface of the skin monitor ?

A

Receptors on the surface of the skin monitor the temperature at the surface of the body.

100
Q

What happens if our body temperate is too hot ?

A

Sweat is released from sweat glands under the skin.

Hairs lie flat.

Blood vessels dilate to allow more blood to enter capillaries that pass close to the skin surface (vasodilation).

101
Q

What happens if our body temperature is too cold ?

A

Muscle contractions increase, causing shivering.

Hairs stand on end.

Blood vessels constrict to reduce blood flow in capillaries (vasoconstriction).

102
Q

What does thermoregulation control?

A

Body temperature

103
Q

Whats vasoconstriction ?

A

Blood vessels constrict to reduce blood flow in capillaries.

104
Q

What happens in vasodilation ?

A

Blood vessels dilate to allow more blood to enter capillaries.

105
Q

How does sweating work ?

A

Sweat glands (in the middle layer of skin, called the dermis) release sweat, which covers the outer layer of skin (the epidermis).

Heat energy from the body is transferred to the water in this sweat and, when it has enough energy, it evaporates.

As it evaporates, it takes the heat energy with it. This lowers the average temperature of the body.

106
Q

How does shivering work ?

A

When we are too cold, muscles start to contract automatically. This makes us shiver.

This process needs energy, which is generated through respiration.

Respiration produces heat, which warms us up.

107
Q

What are hairs on the body contrilled by ?

A

Each hair on the body is controlled by a hair erector muscle in the dermis (middle layer of skin).

108
Q

What happens to the hair erector muscles when we are too hot ?

A

When we are too hot, the hair erector muscle relaxes. This causes the hair to lie flat.

109
Q

What happens to the hair erector muscles when we are too cold ?

A

When we are too cold, the hair erector muscle contracts. This causes the hair to stand on end (which pull on the skin giving you goosebumps).

When all the hairs are standing on end, they trap an insulating layer of air around the body.

110
Q

Blood vessels deep in the skin have layers of what in their walls?

A

Blood vessels deep in the skin have layers of smooth muscle tissue in their walls

111
Q

What happens to the smooth muscle tissue in walls if we are too cold ?

A

If we are too cold, then the muscular walls contract.

This is called vasoconstriction.

This reduces the blood flow to the skin surface and heat energy is kept inside the body

112
Q

What happens to the smooth muscle tissue in walls if we are too hotb ?

A

If we are too hot, then the muscular walls relax.

This is called vasodilation.

This allows more blood to enter and flow through capillaries close to the skin surface. The excess heat energy is transferred to the surroundings.

113
Q

What happens to our blood vessels when we are too cold?

A

Vasoconstriction

114
Q

How many different ways can a hair erector muscle react in thermoregulation?

A

2 - Relax and Contract

115
Q

If blood glucose levels are too high, what can it have a negative impact on ?

A

If blood glucose levels are too high, this can have a negative impact on osmosis (movement of water between cells) by affecting concentration gradients.

116
Q

What is glucose important for ?

A

Glucose is important for respiration.

Respiration releases the energy needed by every living cell.

If there is not enough glucose, an organism cannot produce enough energy.

117
Q

The optimal glucose level in humans is between 6-8 mmol/dm3. What else is true of glucose?

A

Important for respiration
Levels need to be comtrolled
Too much affects osmosis
Too little affects energy production

118
Q

It is very important that an organism is able to control its blood glucose level within what range ?

A

It is very important that an organism is able to control its blood glucose level within a small range.

119
Q

What is Glycogen ?

A

A form of glucose that is insoluble and can be stored for later use

120
Q

How is glycogen involved in the regulation of glucose?

A

If there is too much glucose, it will be converted into glycogen and stored.

If there is too little glucose, the stored glycogen will be converted back into glucose.

121
Q

What is the optimal blood glucose range for humans?

A

6-8 mmol/dm3

122
Q

What are Diabetes sufferers not able to control?

A

Diabetes sufferers are not able to control their blood glucose levels.

123
Q

What are the two different types of diabetes ?

A

Type 1

Type 2

124
Q

In type 1 diabetes, sufferers are unable to produce what ?

A

In type 1 diabetes, sufferers are unable to produce enough insulin.

125
Q

In type 2 diabetes, sufferers can still produce insulin, but whats the problem ?

A

In type 2 diabetes, sufferers can still produce insulin, but their body no longer responds to it.

126
Q

In type 1 diabetes, what do the pancreas cells in the body do ?

A

either produce little or no insulin

127
Q

When does type 1 diabetes develop ?

A

Type 1 diabetes develops during childhood.

128
Q

What is the guess for type 1 diabetes ?

A

We do not know what causes Type 1 diabetes, but we think that the body’s immune system attacks the pancreas cells.

129
Q

What is the treatment for type 1 diabetes ?

A

The main treatment is to inject insulin when blood glucose levels rise too high.

Sufferers can also manage their diet and exercise regularly to keep blood glucose levels as steady as possible.

130
Q

When does type 2 diabetes usually develop ?

A

Type 2 diabetes usually develops later in life.

Old age and being overweight are recognised as two of the primary risk factors.

131
Q

What is the treatment for type 2 diabetes ?

A

Because the body no longer responds to insulin, injecting insulin will not help.

Instead, sufferers must manage their diet and exercise regularly to keep blood glucose levels steady.

132
Q

Water levels in the body must be kept relatively constant to control the amount of water and ions diffusing in and out of cells

What factors disrupt this balance ?

A

Eating
sweating
Eating too much salt
Exhalation

133
Q

Water levels in the body must be kept relatively constant to control the amount of water and ions diffusing in and out of cells

How does illness disrupt this balance ?

A

Illnesses that cause fever, vomiting or diarrhoea can result in dehydration (the blood’s water concentration is too low).

134
Q

Water levels in the body must be kept relatively constant to control the amount of water and ions diffusing in and out of cells

How does eating too much salt disrupt this balance ?

A

This can make the blood ion concentration too high.

135
Q

Water levels in the body must be kept relatively constant to control the amount of water and ions diffusing in and out of cells

How does sweat disrupt this balance ?

A

Water, ions and urea are all lost in sweat.

136
Q

Water levels in the body must be kept relatively constant to control the amount of water and ions diffusing in and out of cells

How does exhalation disrupt this balance ?

A

Water in the lungs leaves the body in the person’s breath.

137
Q

What are three things lost in sweat ?

A

Ions
Water
Urea

138
Q

Why must Blood must be kept isotonic ?

A

Blood must be kept isotonic so that cells do not burst or shrink.

139
Q

What does an isotonic solution have ?

A

An isotonic solution has the same water and ion concentration as cells.

Homeostasis works to regulate the blood’s water and ion concentrations so that it remains isotonic.

140
Q

What does a hypertonic solution have ?

A

A hypertonic solution has a lower water concentration and a higher ion concentration than cells.

141
Q

If the blood becomes hypertonic, what happens to cells ?

A

If the blood becomes hypertonic, cells lose water by osmosis and shrink

142
Q

What does a hypotonic solution have ?

A

A hypotonic solution has a higher water concentration and a lower ion concentration than cells.

143
Q

If the blood becomes hypotonic, what happens to the cells ?

A

If the blood becomes hypotonic, cells gain water by osmosis and burst.

144
Q

Why are kidneys important for homeostasis ?

A

The kidneys are important for homeostasis.

They control the water and ion levels in the blood.

145
Q

Why must ion levels in the body be kept relatively constant ?

A

The body’s ion levels must be kept relatively constant to control osmosis and diffusion between cells in the body.

146
Q

What is the volume of water in the blood is monitored by ?

A

by the hypothalamus in the brain.

147
Q

What is the main function of the kidney ?

A

The main function of the kidney is to filter the and produce urine in order to remove unwanted substances, such as , along with excess water from the body.

148
Q

Why does urea need to be removed from the body ?

A

Urea needs to be removed from the body because it is toxic.

When there is too much urea in the bloodstream, it can harm cells and tissues

149
Q

How is urea formed ?

A

Urea is formed when the digestion of protein results in an excess of (too many) amino acids, which can’t be stored in the body.

150
Q

In the liver, these amino acids undergo a process known as deamination, what is the waste product ?

A

the waste product is ammonia

151
Q

After deamenation what is the ammonia converted into ?

A

The ammonia is then converted into urea and must be excreted from the body as urine.

152
Q

What is urine made of ?

A

Urea and an excess of water

153
Q

Each kidney contains millions of very small structures called what ?

A

Nephrons

154
Q

How many stages are there in the process of urine production ?

A

There are two stages in the process of urine production.

155
Q

What happens in the Ultrafiltration stage of urine production ?

A

The blood capillaries form a knotted cluster called a glomerulus in a part of the nephron called the Bowman’s capsule.

The blood is filtered and all water, urea and salts move into the nephron tubule.

Blood cells and proteins remain in the blood as they are too big to move across the capillary walls.

156
Q

What happens in the Selective reabsorption stage in urine production ?

A

Useful substances, including glucose and some water, are reabsorbed from the tubule back into the bloodstream.

This leaves all urea, excess salts and excess water in the nephron tubule.

This mixture forms urine, which is collected by the kidneys and travels to the bladder to be stored and then excreted.

157
Q

Where does urine production take place?

A

In nephrons

158
Q

What are the two main stages of urine production ?

A

Ultrafiltration

Selective reabsorption

159
Q

The volume of urine produced depends on what ?

A

the internal conditions

160
Q

The volume of water in the blood is monitored by what ?

A

hypothalamus in the brain

161
Q

How does the body respond to having too little water in the blood stream ?

A

The hypothalamus triggers the pituitary gland to release anti-diuretic hormone (ADH).

This increases the permeability (ability of things to pass through) of the kidney tubules. This means that more water is reabsorbed back into the bloodstream.

This results in a small volume of concentrated urine.

162
Q

How does the body respond to having too much water in the blood stream ?

A

The hypothalamus triggers the pituitary gland to stop the release of anti-diuretic hormone (ADH).

This reduces the permeability of the kidney tubules. This means that less water is reabsorbed back into the bloodstream.

This results in a large volume of dilute urine.

163
Q

Which hormone helps to control the volume of water in urine?

A

Anti-diuretic

164
Q

Where does deamination take place?

A

Liver

165
Q

What is one possible treatment for kidney failure ?

A

Dialysis

166
Q

Why do people need dialysis ?

A

It is an essential treatment for people whose kidneys cannot keep the concentrations of urea and salt at an optimum level to ensure that tissue damage does not occur.

167
Q

How does a dialysis machine work ?

A

The patient is linked up to the dialysis machine and their blood flows into the machine.

The machine contains a fluid that is designed to have the optimum concentrations of salts (e.g. sodium and potassium ions) and glucose, as would be found in a healthy person’s blood.

The patients blood passes over a partially permeable membrane in the machine that is designed to replicate the kidney tubules.

The dialysis fluid is on the other side of the membrane. A concentration gradient is established, allowing excess ions and urea to diffuse from an area of high concentration in the patient’s blood to an area of low concentration in the dialysis fluid.

168
Q

What are the disadvantages of a dialysis machine ?

A

Lasts 3-4 hours and is needed 3 times a week.
Increases risk of blood clots and infections.
Expensive process.

169
Q

What are the advantages of a dialysis machine ?

A

Dialysis is a life-saving process.

It gives a patient more time to find a donor kidney.

170
Q

What diffuses from the patient’s blood to the dialysis fluid via a concentration gradient?

A

Ions and urea

171
Q

Why do Many patients choose to have a kidney transplant, which often comes from a close relative ?

A

Close relatives have a higher chance of being a tissue match.

172
Q

Patients receiving a donor kidney often have to take what drugs for the rest of their lives ?

A

Patients receiving a donor kidney often have to take immunosuppressant drugs for the rest of their lives.

173
Q

What do immunosuppressant do ?

A

These drugs suppress the immune system to prevent it from attempting to destroy the foreign cells of the transplanted kidney.

174
Q

Where do some other people get kidneys from ?

A

Kidneys can also be transplanted from people who have recently died, provided that they are a tissue match and have registered onto the organ donor register.

175
Q

What are the advantages of kidney transplants ?

A

The patient does not need to have dialysis treatment, which is time-consuming.

Transplants are cheaper than dialysis in the long run.

176
Q

What are the disadvantages of kidney transplants .

A

The kidney may be rejected by the body.

There can be long waiting lists for kidney transplants.

The patient often has to take immunosuppressant drugs. These can make a patient more prone to other infections.

177
Q

If someone wishes to donate an organ to someone else, what must they have ?

A

A tissue match

178
Q

How many kidneys are people typically born with?

A

2

All Topics GCSE Biology Triple (9 decks)

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