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Biology > Paper 2 Topic 5 > Flashcards

Paper 2 Topic 5 Flashcards

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1
Q

Define Homeostasis

A

The regulation of the internal conditions of a cell or organism to maintain optimum conditions for function, in response to internal and external changes.
Maintaining a stable internal environment despite changing conditions

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1
Q

What is the role of a receptor?

A

Detects changes in the internal or external environment
To detect a stimulus

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2
Q

What is the role of an effector?

A

Brings about a response in the body

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3
Q

What is the role of the coordination centre?

A

Interprets changes and organises a response

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4
Q

Your automatic control systems keep your internal environment stable using a mechanism called ________ ________.

A

Negative feedback

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5
Q

Why does the body need to maintain optimal conditions?

A

For optimal enzyme action and cell function.

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6
Q

What does homeostasis maintain? 3 types

A

Body temperature
Water levels
Blood glucose concentration

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7
Q

In what order are signals passed along the control system?

A

receptor ➔ coordination centre ➔ effector

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8
Q

Where are the coordination centres located in the body? give the 2

A

Brain
Spinal cord

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9
Q

Name the two types of effectors and state what they do.

A

Muscles contract and relax to bring about movement.
Glands release hormones.

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10
Q

What is the nervous system?

A

Relies on electrical impulses that can travel very quickly.

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11
Q

What is the endocrine syststem?

A

Releasing hormones into the blood stream, which means they spread throughout the entire body.

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12
Q

What happens in the negative feedback system?

A

Any change in a system causes an action that reverses the change.

Example
Whenever the levels of something get too high, they’re brought back down.
Whenever the levels of something get too low, they’re brought back up.

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13
Q

What passes along nerve cells?

A

Electrical impulses

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14
Q

What is the gap between two neurones called?

A

Synapse

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15
Q

What is released across a synapse?

A

Chemicals

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16
Q

What is the role of a sensory neurone?

A

To transfer a signal from a receptor to the CNS

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17
Q

What is the role of a motor neurone?

A

To transfer a signal from the CNS to an effector

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18
Q

What does CNS stand for?

A

Central Nervous System

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19
Q

What is the role of a relay neurone?

A

To transfer a signal from a sensory neurone to a motor neurone

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20
Q

What is a reflex?

A

An automatic response to a stimulus

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21
Q

What is the pathway of a reflex arc/ reflex pathway?

A

Stimulus ➔ receptor ➔ sensory neurone ➔ relay neurone ➔ motor neurone ➔ effector ➔ response

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22
Q

What are the two main types of effectors?

A

Muscles and glands

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23
Q

Give an example of a reflex:

A

1) Blinking when you get dust in your eye
2) Sneezing

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24
Why are reflexes important?
They protect us from harm
25
What do glands do?
Glands are organs that release small chemicals called hormones.
26
How the endocrine system work? 4 steps
1) Glands release hormones 2) These chemicals travel around the body in the bloodstream 3) They bind to specific cells that have the correct receptors 4) This will bring about some change within the cells.
27
Give 2 facts about the pituitary gland:
1) It's often referred to as the 'master gland' 2) It releases multiple hormones 3) The hormones it releases control what other glands do
28
Which gland releases thyroxine?
Thyroid
29
What is the role of thyroxine?
Regulates metabolism
30
What happens if the level of thyroxine in the blood is too low?
If the level of thyroxine in the blood is too low, the pituitary gland will release more thyroid stimulating hormone (TSH).
31
What is the role of adrenaline?
Stimulates fight or flight response (higher heart rate etc)
32
Which organ is adrenaline released from?
Adrenal glands
33
Which organ is insulin released from?
Pancreas
34
Name 2 sex hormones that stimulate puberty:
Oestrogen Testosterone
35
Which organ is testosterone released from?
Testes
36
Which organ is oestrogen released from?
Ovaries
37
What is a stimuli?
A change in the environment
38
What happens if blood glucose concentrations fall too low?
There won't be enough glucose for tissue cells to respire
39
After eating, how does our blood glucose concentration change and why?
Blood glucose levels will **increase** after a meal as we **absorb glucose** from the food.
40
Which organ detects changes in blood glucose concentration?
Pancreas
41
Which hormone decreases blood glucose levels?
Insulin
42
What are the two main organs that insulin stimulates to absorb glucose from the blood?
Liver and muscles
43
When glucose is absorbed by the liver for long term storage, what molecule is it converted to?
Glycogen
44
1) When blood glucose levels fall too ___, it's detected by the ________. 2) This causes the pancreas to release the hormone ________ into the bloodstream. 3) This hormone then travels around the body, and binds mainly to cells in the _____. 4) This stimulates those liver cells to break down their stored ________ into _______ and release it into the blood. 5) This extra glucose increases blood glucose levels back up to normal.
1) When blood glucose levels fall too **low**, it's detected by the **pancreas**. 2) This causes the pancreas to release the hormone **glucagon** into the bloodstream. 3) This hormone then travels around the body, and binds mainly to cells in the **liver**. 4) This stimulates those liver cells to break down their stored **glycogen** into **glucose** and release it into the blood. 5) This extra glucose increases blood glucose levels back up to normal.
45
What is puberty?
The period in which adolescents start to develop secondary sexual characteristics.
46
Give 2 examples of secondary sexual characteristics
Increase in height Deepening voice More muscle mass
47
How long is the average menstrual cycle?
28 days
48
Stage 1?
Menstruation - Period of bleeding as the uterus lining breaks down
49
Stage 2?
Building up of the uterus lining
50
Stage 3?
Ovulation - Release of the egg from the ovaries
51
Stage 4?
Maintenance of uterus lining
52
What happens after stage four if there is no fertilised egg?
Cycle starts again
53
If a fertilised egg implants into the uterus lining then the menstrual cycle...
... stops and the lining is maintained.
54
Which hormone stimulates the uterus lining to develop?
Oestrogen
55
Which organ are both luteinising hormone (LH) and follicle stimulating hormone (FSH) released from?
Pituitary gland
56
Which hormone stimulates the egg to be released around day 14 (ovulation)?
Luteinising hormone (LH)
57
Which hormone stimulates the egg follicle to mature?
Follicle stimulating hormone (FSH)
58
Which hormone maintains the lining of the uterus?
Progesterone
59
What is contraception?
A method or device used to prevent pregnancy
60
Which hormones can hormonal contraceptives contain?
Oestrogen and Progesterone
61
How can oestrogen act as a contraceptive?
Inhibit FSH production, so that eggs can't mature
62
How can progesterone act as a contraceptive?
Stimulate the production of mucus in the cervix, so sperm can't enter the uterus
63
Does the combined oral contraceptive pill ('the pill') contain oestrogen, progesterone, or both?
Both
64
Which is longest and which is shortest lasting? Intrauterine device Contraceptive implant Contraceptive injection Contraceptive patch
Shortest: Patch Longest: Device
65
How does a spermicide act as a contraceptive?
Destroys sperm cells
66
The diaphragm sits over the ______ to prevent sperm from entering the uterus.
cervix
67
If a women undergoes sterilisation, which structure is cut and tied?
Fallopian tubes / oviducts
68
If a man undergoes sterilisation, which structure is cut and tied?
Sperm duct
69
What does follicle stimulating hormone do?
Stimulate an egg to mature
70
What does luteinising hormone do?
Stimulate an egg to be released (ovulation)
71
If a woman cannot conceive naturally, she can be given ___ and __, which in many cases will restore fertility.
FSH LH
72
IVF stands for:
In Vitro Fertilisation
73
The stages of in vitro fertilisation (5)
1) A woman is **given FSH and LH** to stimulate their eggs to mature. 2) These **eggs can then be collected** from the woman's ovaries. **Sperm is also collected** from the male. 3) The eggs are then **fertilised** by the sperm. 4) These fertilised eggs are then **left to grow into embryos** in a laboratory incubator. 5) Once the embryos are large enough, they are **transferred to the women's uterus**, so that they can develop into a foetus.
74
What is Intra-Cytoplasmic Sperm Injection (ICSI)?
Sperm is injected into an egg cell with a tiny needle
75
Why are embryos kept in an incubator whilst in the laboratory?
To provide the optimum temperature for enzymes and thus cell growth
76
Give 3 cons of IVF:
-> It can be stressful and emotionally upsetting -> Can cause abdominal pain and vomiting -> It doesn't always work -> High chance of multiple births and associated complications
77
Why do some people think IVF is unethical? Give 1
-> It could lead to 'designer babies' if parents can select embryos with certain traits -> Some embryos (which had the potential for human life) are destroyed
78
During IVF, where are the egg and sperm mixed?
In a laboratory
79
Which organ is adrenaline released from?
Adrenal gland
80
When is adrenaline released?
When you're scared
81
Adrenaline causes changes in the body to prepare for a ‘fight or flight’ response. Give 3 of these changes.
Increase heart rate Increase blood pressure Increase blood flow to muscles Increases blood sugar (glucose) levels
82
Adrenaline causes the conversion of which substances?
Glycogen ➔ glucose
83
Where is the thyroid gland located?
In the neck
84
What does thyroxine do?
Increase your metabolic rate (the rate at which chemical reactions are taking place).
85
How is the production of thyroxine regulated?
The pituitary gland *produces* Thyroid Stimulating Hormone (TSH), which *stimulates* the thyroid gland to *produce* thyroxine. Thyroxine then *inhibits* the production of TSH from the pituitary gland.
86
What happens if thyroxine levels are -> too low? -> too high?
1) If thyroxine levels are too low - the pituitary gland will release TSH. This then stimulates the thyroid gland to release more thyroxine. So thyroxine levels in the blood increase back up to normal. 2) If thyroxine levels are too high - the thyroxine will inhibit the pituitary gland from producing TSH. Less TSH means that the thyroid gland won't release as much thyroxine. So thyroxine levels in the blood fall back to normal.
87
Which organ is TSH released from?
Pituitary gland

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