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Biology > Topic 5 - Homeostasis and response > Flashcards

Topic 5 - Homeostasis and response Flashcards

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1
Q

Why do plants produce hormones?

A

To control and coordinate growth and responses to light (phototropism) and gravity (geotropism)

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2
Q

What is auxin?

A

It is the hormone that control growth near tips of roots and shoots.

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3
Q

What does unequal distribution in auxins in roots and shoots cause.

A

Causes unequal growth

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4
Q

What is positive phototropism and where does it take place and is there more auxin on the bright or shaded side and what does this cause?

A

Phototropism is a positive response in shoots so the shoot bends towards the light. There is more auxin on the shaded side this causes increased cell growth.

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5
Q

What is negative phototropism and where does it take place and is there more auxin on the bright or shaded side and what does it cause?

A

Negative phototropism takes place in the roots and it bends away from the light. More auxin is on the shaded side but inhibits growth or cell elongation.

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6
Q

Define homeostasis.

A

Homeostasis is the regulation of internal conditions to maintain optimum internal environment in response to internal or external change

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7
Q

What are the three main thing homeostasis controls?

A

Body temperature - 37°C
Blood Glucose Concentration
Water levels

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8
Q

What is homeostasis controlled by?

A

Nervous system and the hormonal system (endocrine system)

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9
Q

What is the cyclical process where the nervous system and the endocrine controls homeostasis.

A

1) Receptors in organs detect changes in internal or external environments (stimuli)
2) Information is sent via hormones or nervous impulses.
3) Coordinators such as the brian, spinal cord and pancreas process information and sends information via hormones or nervous impulses.
4) The information is sent to the effectors which respond to the stimulus. Effectors are either muscles or glands.

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10
Q

What is the nervous system made of?

A

The CNS = brain + nervous system
The nerves - bundles of nerve cells.

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11
Q

What is the nervous system used for?

A

Allows humans to react to their surrounding and coordinate their response.

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12
Q

What do nerves transmit to send information?

A

Electrical impulses.

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13
Q

What are reflexes?

A

Reflexes are unconscious and do not involve the brain. They only use three neurones. Reflexes are designed to keep the body safe from harm.

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14
Q

What happens in the reflex arc when you move your hand away from a pin?

A

Receptors in the skin detect the stimuli (sharp pin).

Then an electrical impulse is sent along a sensory neuron to the spinal cord.

Then an impulse passes through a relay neurone in the spinal cord (coordinator).

Then the relay neurone sends an impulse along a motor neurone to the muscles.

The muscles (effector) contract, pulling your hand away quickly.

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15
Q

What is a synapse?

A

A gap between two neurones.
Chemical released diffuses across the gap and binds to receptors on next neurone to trigger the electrical impulse.

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16
Q

What is the name of the chemical released at the synapse?

A

Neurotransmitters

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17
Q

What is the brain made of?

A

Billions of interconnected neurones.

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18
Q

Where is the cerebral cortex and what is the role of it.

A

It controls conscious thought, language, memory and intelligence. (Higher brain functions)

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19
Q

Where is the cerebellum and what does it do?

A

Coordinates muscle contractions and helps with balance and control of the body.

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20
Q

Where is medulla and what does it do.

A

Controls unconscious behaviours like heart and breathing rate.

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21
Q

Where is the pituitary gland and what does it do?

A
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22
Q

How is the brain studied?

A

Studying people with brain damage/injury.
Electrically stimulating the brain or measuring electrical activity.
MRI scans to visualize the brain structure.

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23
Q

What are the ethical issues with studying people with brain damage?

A

Need Consent for this.

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24
Q

Why is the brain so difficult to understand and treat.

A

Inside a skull so hard to access to see how it works and treat it. It is complex (not fully understood) and is delicate (easily damaged in surgery). Nervous tissue is difficult to repair/replace. Not all drugs can reach the brain due to membranes.

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25
Label all the parts of the eye forget the part in the middle.
26
What is the role of the optic nerve?
Transmits electrical impulses to the brain.
27
What is the role of the retina?
Contains light receptors rod and cone cells.
28
What is the role of the sclera?
Support and protection
29
What is the role of the iris?
Muscles that control how much light enters the eye through the pupil.
30
What is the role of the cornea?
Transparent layer that protects pupil and helps focus.
31
What is the role of the ciliary muscles?
Helps control the size and shape of the lens to foucs light onto the retina.
32
In bright light how does the eye adapt?
The circular muscles contract, radial muscles relax. - Smaller pupil
33
In dim light how does the eye adapt?
Circular muscles relax, radial iris muscles contract. - Larger pupil
34
How does the eye accommodate to focus nearby objects?
Ciliary muscles contract, suspensory ligaments loosen. So there is more refraction due to thicker lens.
35
How does the eye accommodate to focus far away objects.
Ciliary muscles relax, suspensory ligaments tighten. So there is less refraction due to thinner lens.
36
What is hyperopia and how is it caused and how can it be fixed?
Hyperopia - Long sightedness, near objects become blurry. The lens is too flat so it cannot refract light enough. Can be fixed by using glasses with convex lens or contact lenses. Diverges light rays.
37
What is myopia and how is it caused and how can it be fixed?
Myopia - Short sightedness, far objects become blurry. The lens is too curved so it refracts light too much. Fixed with concave lens in glasses or contact lenses. Converges light rays.
38
What are other treatment options for hyperopia and myopia?
Laser eye surgery to change cornea shape. Lens replacement surgery for cataracts (cloudy lens)
39
How is temperature control in the body regulated?
By the thermoregulatory centre in the brain. Containing receptors that detect blood temperature. Skin receptors can also detect temperature change and send nervous impulses to the thermoregulatory system.
40
If receptors detect the body is to cold what changes are made to increase body temperature?
Vasoconstriction - narrow lumen in blood vessels to reduce blood flow. Muscle contraction (shivering) - Increase respiration. Hairs stand up (goosebumps) - to try and trap a layer of air and sweat stopping.
41
If receptors detect the body is to hot what changes are made to decrease body temperature?
Vasodilation - Wider lumen in blood vessels to increase blood flow. Hairs lie flat Swearing increases - heat energy is used to evaporate the sweat from skin.
42
What is the endocrine made of and what does it do?
Made up of glands that secrete hormones directly into the bloodstream.
43
What does the blood do in the endocrine system?
Carries hormones to target cells around the body where it has an effect.
44
How is the endocrine system different to the nervous system?
The endocrine system uses chemicals not electrical impulses. Endocrine system uses blood instead of nerves. Endocrine system response is slower to take an effect. Endocrine system has longer lasting effects. Endocrine system can affect multiple organs at once.
45
What does the adrenal gland do and where is it found?
secretes adrenaline found above the kidneys.
46
What does the pancreas do?
Secretes insulin and glucagon.
47
What does the ovary do?
Secretes oestrogen and progesterone in females.
48
What does the testes do?
Secretes testostorone in males.
49
What does the thyroid gland do and where is it found?
Secretes thyroxine found in throat.
50
What hormones does the pituitary gland secrete?
FSH and LH - involved in the menstrual cycle.
51
How is blood glucose controlled?
Blood glucose is monitored and controlled by the pancreas.
52
How does the body respond when blood glucose increases.
Receptors in pancreas detect the increase in blood glucose levels. Pancreas releases insulin. Insulin hormone travels in blood. Insulin binds to liver cells and makes them absorb glucose from blood. Blood glucose levels decreases excess glucose in liver and muscle cells is converted into glycogen for storage.
53
How does the body respond when blood glucose levels drop too low after exercise?
Receptors in pancreas detect decrease in blood glucose levels. Pancreas releases glucagon. Glucagon hormone travels in blood to the liver. Glucagon binds to the liver cells and makes them release glucose into the blood. This is done by breaking down stores of glycogen to release glucose. This causes the blood glucose levels increase
54
How is diabetes caused?
When blood glucose levels are not being controlled properly.
55
What is type 1 diabetes and how do you treat it?
When there is not enough insulin produced by the pancreas. To treat it you have insulin injections to help lower blood glucose.
56
What is type 2 diabetes and how do you treat it?
When insulin receptors on target cells such as liver do not respond to insulin anymore. To treat it low carbohydrate diet and exercise and sometimes glucose lowering medication.W
57
What is a risk factor for type two diabetes?
Obesity.
58
Why is it important to maintain water levels in the body.
Water levels in the body need to be the same as the cell cytoplasm to prevent osmosis. As if water moves out the cell can shrink if water moves in it can burst.
59
What are the ways water ions and urea is removed?
Water ions and urea can be lost from skin in sweat. Water is lost as water vapour when we exhale. Excess water ions and urea removed by kidneys into urine which is then excreted. - controlled by hormones.
60
How can we remove excess nitrogen?
Proteins can be broken down in the body into amino acids which contain nitrogen and cannot be stored in the body. The excess amino acids travel to the liver where they are deaminated which converts them into ammonia then is converted into less toxic called urea.
61
How does the kidneys remove urea from the blood?
The kidneys filter urea from the blood and it is excreted as urine from the bladder.
62
How does the kidney keep the useful products?
Useful substances like glucose and some ions and some water are absorbed back into the blood after being filtered by the process called selective reabsorption.
63
What happens if the kidneys do not work properly?
There will be a build up of toxic urea in the body.
64
What are the two ways to treat kidney failure?
Dialysis Kidney transplant
65
How does dialysis work?
A patient is attached to a machine that removes blood from the body and filters it. Urea is removed and blood is returned to the body. Dialysis fluid flows next to blood causing diffusion of urea and excess ions out of the blood into the fluid. Glucose is not removed as the dialysis fluid has the same concentration as it.
66
How does a kidney transplant work?
Kidney is given from a dead or living donor that is a tissue/blood type match to reduce chances of rejection.
67
What are the benefits and the negatives of Dialysis?
Used to keep people alive while they wait for a kidney transplant. It is not a long term solution as it can be inconvenient.
68
What are the benefits and negatives of a kidney transplant?
Long term solution. More convenient. Shortage of donors. Will require immunosuppressants for life to prevent rejection which could have side effects.
69
How is the volume of water lost in urine controlled?
It is controlled by the pituitary gland that secretes the hormone ADH. This is an example of negative feedback.
70
Give the process where the body changes to reduce the amount of water in the blood.
Receptors detect high blood water levels. Pituitary gland releases less ADH into blood. Less water released into blood so more removed in urine. Blood water level decreases.
71
What does testosterone cause?
Sperm production (male gamete)
72
The pituitary gland secretes FSH and LH what does each one do?
FSH - Egg maturing in ovary LH - Egg released from ovary
73
What does the ovary release and what does it do?
Releases oestrogen and progesterone which build and maintains uterus lining.
74
How long is the menstrual cycle and at what day is the egg released?
28 Days on day 14 egg is released from the ovary (ovulation)
75
What effect does an increase in FSH have on the other hormones and why?
Causes an increase in oestrogen production. This is because the uterus lining begins to develop ready for egg release.
76
What effect does an increase in Oestrogen have on the other hormones and why?
Causes LH production. This is because egg is only released when uterus lining is ready to receive it. Inhibits FSH production. This is because only one egg matures in a cycle.
77
What does an increase in progesterone cause?
Inhibits FSH and LH production. To prevent any other eggs maturing or being released during pregnancy.
78
During pregnancy is progesterone level low or high?
High
79
Define contriception .
Any method used to try and prevent pregnancy. It is a form of controlling fertility.
80
What does the contraception method pill do?
Contain progesterone and oestrogen to inhibit FSH and LH so no eggs mature or are released from the ovaries so cant be fertilised.
81
What does spermicide do?
Kills or disables sperm so they can't swim to the egg.
82
What is a IUD?
Placed in uterus to prevent an embryo from implanting in the wall.
83
What is steralisation?
It is a permanent solution to cut tubes that release gametes.
84
What are ways to treat infertility?
Fertility drugs IVF.
85
How do fertility drugs work?
Fertility drugs including FSH and LH injected to increase egg maturation and release.
86
How does IVF work?
1) Eggs are collected - Inject FSH and LH drugs to increase the number of eggs maturing and released at the ovary. 2) Sperm is collected 3) Then the sperm and the egg are encouraged to fertilise in a lab or test tube. 4) Once fertilisation has occured they are left to develop to form an embryo. The embryos can be replaced back in the uterus to create a pregnancy.
87
What are the PROS and CONS of an IVF?
Allows parents to have a biological child. Very physically and emotionally stressful. No higher success rate than normal. Can lead to multiple births and risk health of babies and mother.
88
What does thyroxine do?
Controls the basal metabolic rate which is important for growth and development and other processes such as stimulating protein synthesis.
89
Why is Thyroxine released?
In response to thyroid stimulating hormone TSH which is released in the pituitary gland.
90
What happens to TSH when the level of thyroxine level is higher than normal?
The secretion of TSH from the pituitary gland is inhabited.
91
When is adrenaline released?
In times of fear or stress to prepare the body for 'fight or flight' to respond.
92
What are some effects on the body of adrenaline?
Increases supply of oxygen and glucose to cells in the brain and muscles, for example increases heart rate.
93
Where is negative geotropism found and describe the postition of auxin?
Negative geotropism found in shoots. Grows against the pull of gravity as more chance of finding light. Auxin moves to lower side of the shoot causing more cell elongation so shoot bends upwards.
94
Where is positive geotropism found and describe the position of auxin?
Positive in roots. Grow with the pull of gravity so grows into soil for support and to find water. Auxin moves to lower side inhibiting cell elongation at the lower side so upper side grows more bending root down.
95
What can plant hormones be used for?
To control plant growth in agriculture.
96
What can auxins be used for by humans?
Weed killers - causes plants to grow too fast and collapse. Rooting powders - For cuttings To promote growth in tissue culture.
97
In plants what is ethene used for and how do humans use it?
In plants it controls cell division and fruit ripening. Humans use it in the food industry to control ripening to help with transport and storage.
98
What do gibberellins do in plants and what is the use for humans.
In plants this initiates seed germination. For humans can be used to end seed dormancy, promote flowering, increase fruit size.

Biology (9 decks)

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