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Biology > Topic 7 - Animal Coordination, Control And homeostasis > Flashcards

Topic 7 - Animal Coordination, Control And homeostasis Flashcards

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1
Q

What is the endocrine system?

A

A network of glands that produce and secrete hormones into the bloodstream

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2
Q

What is a hormone?

A

A cell signalling molecule produced by endocrine glands and released into the blood
Travels to a target organ and bi do to receptors on effectors initiating a response

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3
Q

Compare the endocrine and nervous systems

A

Endocrine uses hormones, nervous uses nerve impulses
Hormones travel in the blood stream to target organ
Nerve impulse travel via neurones to the effectors
Endocrine is a slower response
Endocrine lasts until all hormones have broken down which takes a long amount of time whereas nerve lasts until the nerve impulse stops which takes a short amount of time

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4
Q

What is the pituitary gland?

A

Described as the ‘master gland’

It is an Ed doctrine gland that produces hormones which control other glands

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5
Q

What are the adrenal glands?

A

Endocrine glands that produce adrenaline

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6
Q

Where are the adrenal glands located?

A

Above the kidneys

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7
Q

What is adrenaline?

A

A hormone produced by the adrenal glands that is involved in the ‘fight or flight’ response

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8
Q

State the effects of adrenaline on the body

A

Increases heart rate
Increases blood pressure
Increases blood flow to muscles
Increases blood glucose levels

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9
Q

Describe how adrenaline increases heart rate and blood pressure

A

Segregated by the adrenal glands, travels in the blood to the heart
Binds to specific receptors on cells in the heart
Causes heart muscle to contract more forcefully and frequently
Heart rate increases, blood pressure increases

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10
Q

Describe how adrenaline increases respiration at muscle tissues

A

Adrenaline binds to specific receptors on cells in the liver
Triggers breakdown of glycogen stores and release of glucose so blood glucose levels increase
Increased heart rate causes greater blood flow to muscles
So muscle cells receive more oxygen and glucose for respiration

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11
Q

What is negative feedback?

A

A corrective mechanism that allows only small shifts from a set point
It reverses a change in conditions e.g if the concentration of a hormone increases, negative feedback systems work to reduce the concentration back to normal level

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12
Q

What is the thyroid gland?

A

Endocrine gland that produces thyroxine

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13
Q

Where is the thyroid gland located?

A

In the neck

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14
Q

What is thyroxine?

A

A hormone secreted by the thyroid gland that controls metabolic rate, heart rate and temperature

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15
Q

What is metabolic rate?

A

The rate at which biochemical redactions occur in cells

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16
Q

Describe how thyroxine is released

A

Hypothalamus secretes TRH
TRH stimulates secretion of TSH from pituitary gland
TSH stimulates the release of thyroxine from the thyroid gland

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17
Q

What does TRH stand for?

A

Thyrotropin releasing hormone

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18
Q

What does TSH stand for?

A

Thyroid-stimulating hormone

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19
Q

Describe how a negative feedback system controls blood thyroxine levels

A

If blood thyroxine levels increase above a set point, TRH and TSH secretion is inhibited. Less thyroxine is produced by the thyroid gland. Thyroxine levels return to normal
If blood thyroxine levels decrease below a certain point, TRH and TSH secretion is increased. More thyroxine is produced by the thyroid gland. Thyroxine levels return to normal

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20
Q

How do the ovaries act as an endocrine gland?

A

They secrete oestrogen into the bloodstream

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21
Q

How do the testes act as an endocrine gland?

A

They secrete testosterone into the bloodstream

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22
Q

What is the menstrual cycle?

A

The cycle in women (typically lasting 28 days) that involves:
Shedding of uterus lining (menstruation)
Repair of uterus lining
Release of egg (ovulation)
Maintenance of uterus lining

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23
Q

Describe the stages of the menstrual cycle

A

Days 1-4: if fertilisation and implantation do not occur the uterus lining sheds and the egg is expelled with it (menstruation)
Days 4-14: uterus lining thickens and blood vessels grow in preparation for the implantation of an egg
Day 14: egg released from a follicle into the oviduct (ovulation)
Days 14-28: uterus lining maintained so implants can occur

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24
Q

Name the hormones that control the menstrual cycle

A

Follicle stimulating hormone (FSH)
Oestrogen
Luteinising hormone (LH)
Progesterone

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25
Q

Describe the role of FSHin the mentrual cycle

A

Secreted by the pituitary gland
Transported in the bloodstream to the ovaries
Triggers the development of a follicle in the ovaries which releases oestrogen

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26
Q

Describe the role oestrogen plays in the menstrual cycle

A

Secreted by the ovaries
Repairs and thickens the uterus lining
Inhibits secretion of FSH from the pituitary gland
Stimulates secretion of LH from the pituitary gland

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27
Q

Describe the role of LH in the menstrual cycle

A

Secreted by the pituitary gland
Transported in the bloodstream to the ovaries
Surge in LH triggers ovulation
Stimulated follicle remains to develop into a corpus outermost which secreted progesterone

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28
Q

What is a corpus luteum?

A

Temporary endocrine structure
Mass of cells that releases progesterone
Degenerates after a few days

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29
Q

Describe the role of progesterone in the menstrual cycle

A

Secreted by the corpus luteum
Stimulates the growth of blood cell Eli’s in the uterus lining (in preparation for implantation)
Inhibits the release of FSH and LH
If no implantation occurs, progesterone levels decrease and the uterus lining sheds. FSH increases and the cycle starts again

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30
Q

What happens to protest levels if fertilisation and implantation occur?

A

The placenta produces progesterone so levels remain high

This prevents further ovulation and maintains the uterus lining

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31
Q

What are contraceptives?

A

A method or device utilised to prevent pregnancy

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32
Q

Which hormones can be taken to prevent pregnancy?

A

Progesterone on its own

Progesterone with oestrogen

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33
Q

How does progesterone prevent pregnancy?

A

Sperm find it more difficult to enter the uterus as the cervical mucus is thickened
Thins the uterine lining, reducing the likelihood of egg implantation
Prevents ovulation in some women (but not all)

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34
Q

How does oestrogen prevent pregnancy?

A

It inhibits FSH, preventing ovulation

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35
Q

How can progesterone be administered as a contraceptive?

A

Injection

Mini pill taken daily

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36
Q

How can progesterone and oestrogen be administered as a contraceptive?

A

Skin patch

Combined pill

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37
Q

What are the benefits of hormonal contraceptive methods?

A

99% effective when used properly
Generally longer lasting than non-hormonal methods
Used to treat other conditions

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38
Q

What are the risks of hormonal contraceptive methods?

A

Side effects
Do not protect against STIs
May involve uncomfortable medical procedures
Not effective if used incorrectly

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39
Q

Describe the barrier methods of contraception

A

Prevent the sperm and egg meeting

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40
Q

What are the benefits of barrier methods of contraception?

A

No side effects
Condoms prevent the spread of stis
Condoms are simple and quick to use

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41
Q

What is the main risk of barrier methods of contraception?

A

Less effective than hormonal methods

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42
Q

What two methods are used to treat infertility?

A

IVF

Clomifene therapy

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43
Q

Describe the role of hormones in IVF

A

FSH and LH given to a woman to stimulate egg production and ovulation
Eggs retrieved from the woman’s ovaries and fertilised in vitro
Resultant embryo transferred to the woman’s uterus

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44
Q

Outline clomifene therapy

A

Prescription of drug which stimulates secretion of more FSH and LH which triggers egg production and ovulation

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45
Q

What is homeostasis?

A

The maintenance of a stable internal environment in the body

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46
Q

Why is homeostasis important?

A

To ensure optimum conditions for enzymes and cellular processes in the body

47
Q

State three conditions within the body that must be controlled by homeostasis

A

Temperature
Water levels
Blood glucose concentration

48
Q

What is thermoregulation?

A

The maintenance of core body temperature

49
Q

Why must body temperature be controlled?

A

Enzymes work best at their optimum temperature. Deviations cause a decrease in the rate of enzyme-controlled reactions

50
Q

What is the optimum temperature for enzymes in the human body?

A

37°C

51
Q

What does the maintenance of an ideal body temperature depend on?

A

A negative feedback system involving:
Receptors
Hypothalamus
Effectors

52
Q

Where are the temperature sensitive receptors located?

A

Hypothalamus

Skin

53
Q

What is the function of receptors in the skin and in the hypothalamus?

A

They detect changes in blood temperature and send information to the hypothalamus

54
Q

What is the function of the hypothalamus?

A

It coordinates information from the receptors and sends instructions to the effectors

55
Q

What is the function of the effectors?

A

They produce a response to counteract the change in blood temperature and return it to the set point

56
Q

Outline the responses of the body to an increase in temperature about 37°C

A

Vasodilation
Sweating
Erector muscles relax, hairs lie flat

57
Q

What structure produces sweat?

A

Sweat glands found in the dermis

58
Q

How is sweat released from the skin?

A

Pores in the epidermis release sweat onto the skin’s surface which then evaporates

59
Q

How does sweating help to reduce body temperature?

A

Heat energy is used to evaporate sweat.

Increased heat transfer from The skin to the environment decreases body temperature

60
Q

What is vasodilation?

A

Dilation of blood vessels near the skin surface
Blood flows closer to the skin surface
Greater heat loss to the surroundings

61
Q

Outline the responses of the body to a decrease in temperature below 37°C

A

Vasoconstriction
Shivering
Hair erector muscles contract
Little sweat is produced

62
Q

How does shivering help to increase body temperature?

A

Involuntary contraction of muscles generates heat energy from respiration

63
Q

How does the contraction of hair erector muscles help to increase body temperature?

A

Hairs stand on end creating pockets of air between hairs and a layer of insulation

64
Q

What is vasoconstriction?

A

Construction of blood vessels near skin surface
Less blood flows close to the skin surface
Less heat loss to the surroundings

65
Q

Which organ is responsible for the maintenance of blood glucose concentrations?

A

Pancreas

66
Q

How are blood glucose concentrations controlled?

A

By the hormones insulin and glucagon which are secreted by the pancreas

67
Q

Insulin and glucagon and antagonistic hormones. What does this mean?

A

They have opposite effects which counteract one another

68
Q

Describe the role of insulin in the regulation of blood sugar levels

A

Causes liver and muscle cells to increase their uptake of glucose from the blood
Glucose is converted into glycogen, a storage molecule

69
Q

Describe the role of glucagon in the regulation of blood sugar levels

A

Causes the breakdown of glycogen to glucose in the liver

Glucose is released into the blood

70
Q

What is the control of blood glucose concentration an example of?

A

Negative feedback

71
Q

Describe what happens when blood glucose concentrations become too high?

A

Pancreas secretes insulin and stops producing glucagon
Liver and muscle cells increase uptake of glucose
Glucose is converted to glycogen and stored
Some glucose may be stored as lipid in tissues
Blood glucose concentration decreases, returning to normal level

72
Q

Describe what happens when blood glucose concentrations become too low

A

Pancreas secreted glucagon and stops producing insulin
Liver cells convert glycogen into glucose which is released into blood
Blood glucose concentration increases, returning to normal level

73
Q

What is diabetes?

A

A condition where the homeostatic control of blood glucose levels stop working

74
Q

What is the cause of type 1 diabetes?

A

Pancreas does not produce enough insulin

75
Q

How is type 1 diabetes treated?

A

Daily insulin injections at meal times
Limiting intake of refined sugars
Regular exercise

76
Q

What is the cause of type 2 diabetes?

A

Person develops insulin resistance or doesn’t produce enough insulin (often due to obesity)

77
Q

How is type 2 diabetes treated?

A

Balanced up diet
Exercise
Medication

78
Q

How does exercise help to control diabetes?

A

It increases respiration in muscles cells. Excess glucose is removed from the blood to produce energy in the form of ATP

79
Q

Why are type 2 diabetics advised to replace simple carbohydrates with more complex carbohydrates?

A

Simple carbohydrates are broken down quickly so can raise blood sugar levels rapidly
Complex carbohydrates take longer to break down so have a reduced effect on blood glucose levels

80
Q

What is the body mass index?

A

A value based on height and mass used to categorise an individual as underweight, normal weight, overweight, or obese

81
Q

How is BMI calculated?

A

Mass/height^2

82
Q

What BMI values indicate obesity and an increased risk of type 2 diabetes?

A

A BMI larger than 30

83
Q

How is an individual’s waist to hip ratio calculated?

A

Waist circumference/hip circumference

84
Q

What does a waist to hip ratio higher than 1.0 in males or 0.85 in females indicate?

A

Abdominal obesity

Increased rick of developing type 2 diabetes

85
Q

What is osmoregulation?

A

The maintenance of constant water levels in the body fluids of an organism

86
Q

Why is osmoregulation important?

A

Prevents cells bursting or shrinking when water enters or leaves by osmosis

87
Q

Describe what happens to an animal cell if it is placed into a solution with a higher water concentration

A

Water molecules move down their water concentration gradient into the cell by osmosis
Pressure inside the cell increases, cell bursts (lysis)

88
Q

Describe what happens to an animal cell if it is placed into a solution with a lower water concentration

A

The water molecules move down their water concentration gradient out of the cell by osmosis
Pressure inside the cell decreases, cell shrinks (crenation)

89
Q

What is the function of the kidneys?

A

Removes toxic waste substances from the body
Alters blood water levels
Alters blood ion levels

90
Q

What is urine?

A

Waste product of the kidney that contains urea, excess water and excess ions

91
Q

How is urea produced?

A

From the breakdown of excess amino acids

92
Q

What are the structures of the urinary system?

A 
Kidney
Renal vein
Renal artery
Ureter
Urethra
Bladder
93
Q

What is the function of the renal artery?

A

Supplies blood to the kidneys

94
Q

What is the function of the renal vein?

A

Drains blood from the kidneys

95
Q

What is the function of the ureter?

A

Takes urine to the bladder from the kidneys

96
Q

What is the function of the urethra?

A

Releases urine from the bladder, out of the body

97
Q

What is a nephron?

A

Functional unit of the kidney where filtration and selective reabsorption takes place

98
Q

Describe filtration in the kidneys

A 
Blood flows through the glomerulis under high pressure
Small molecules(e,g urea, glucose), water and ions are filtered out of the blood and into the Bowman’s capsule of the nephron
99
Q

Why do large molecules (e,g red blood cells, proteins) remain in the blood?

A

They are too big to fit through the pores in the capillary walls

100
Q

Which substances are selectively reabsorbed from the nephron tubule?

A

All sugars
Some water
Some ions

101
Q

What happens to the molecules not selectively reabsorbed?

A

They travel down the kidney tubule as urine and are transported to the bladder via the ureter. Here they are stored and eventually excreted

102
Q

How is the concentration and volume of urine controlled?

A

By the secretion of anti-diuretic hormone (ADH)

103
Q

What produces ADH?

A

Pituitary gland

104
Q

Describe how ADH affects the reabsorbtion of water from the kidney tubules

A

It increases the permeability of the collecting ducts, enabling more water to be reabsorbed into the blood

105
Q

What is required o maintain the ideal water content of blood?

A

A negative feedback system involving:
Receptors I. The hypothalamus
hypothalamus
Effectors

106
Q

Describe the negative feedback loop which occurs when low blood water concentration is detected

A

Receptors detect low blood water content and send information to the hypothalamus. This coordinated the information and sends instructions to the pituitary gland
This increases ADH secretion. ADH increases collecting duct permeability so more water is reabsorbed
Blood water content increases, more concentrated urine is produced

107
Q

Describe the negative feedback loop which occurs when high blood water concentration is detected

A

Receptors detect high blood water content and send information to the hypothalamus. This coordinated the information and sends instructions to the pituitary gland
This secretes less ADH, collecting duct becomes less permeable so less water is reabsorbed
Blood water content decreases. More dilute urine is produced

108
Q

How can kidney failure be treated?

A

Transplant

Dialysis

109
Q

What is kidney dialysis?

A

A machine artificially filters a patient’s blood

110
Q

How does kidney dialysis work?

A

Selectively permeable barrier separates patient’s blood from dialysis fluid
Materials are exchanged across the barrier, e.g urea, excess ions and water move out of the blood and into the dialysis fluid
Large cells and proteins remain in the blood

111
Q

Describe the composition of dialysis fluid

A

No urea

Same concentration of glucose and ions as in normal blood plasma

112
Q

What does a kidney transplant involve?

A

Taking a kidney from a living donor or someone recently deceased and implanting it into the patient

113
Q

What aid the risk associated with kidney transplants?

A

Risk of the body rejecting the transplanted kidney

114
Q

What precautions are takes to minimise the Risk of rejection?

A

Tissue typing ensures that the transplanted organ is ‘compatible’ with the recipient
Immunosuppressant drugs help prevent the immune system from rejecting the organ

Biology (8 decks)

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