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Biology > B5: Homeostasis and response > Flashcards

B5: Homeostasis and response Flashcards

1
Q

What is the purpose of the nervous system?

A

Enable humans to react to their surroundings

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2
Q

Adaptations of nervous system? (1)

A

Neurones have a cell body

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3
Q

What is a reflex reaction?

A

A rapid reaction - involuntary automatic response that doesn’t involve the conscious parts of your brain as the ‘coordinator’ of the reaction.

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4
Q

What are the 3 types of neurones involved in reflex function?

A

sensory neurones : carry impulse from dense organs to CNS
motor neurones : carry impulse from CNS to effector
relay neurones : connect sensory/motor neurones in CNS

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5
Q

Sensory neurones structure?

A

Long
Cell body branches off middle of axon

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6
Q

Motor neurones structure?

A

Long
Have large cell body at one end with dendrites branching off it

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7
Q

Relay neurones structure?

A

Short
Small body cell at one end with many dendrites branching off it

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8
Q

Reflex function/arc order?

A

Stimulus —> receptor —> sensory neurones —> relay neurones —> motor neurones —> effector —> response

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9
Q

Explain reflex arc when you touch a hot object?

A

When you touch a hot object, RECEPTOR is stimulated
- electrical impulse from receptor to sensory neurones
- at end of sensory neurones there is a SYNAPSE
- synapse relaxes a chemical which DIFFUSES to relay neurone
-this triggers electrical impulse on relay neurone and passed along to another synapse
-another chemical released/ triggers impulse in MOTOR NEURONES
- electrical impulse passes from motor neurones to effector
- muscle contracts pulling hand away

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10
Q

REQUIRED PRACTICAL: REACTION TIME?

A
  1. PERSON 1 sit on chair with arm on table, with dominant hand on edge
  2. PERSON 2 hold ruler so 0cm is level with top thumb
  3. PERSON 2 drops ruler, person 1 catches it as quick as possible
  4. Record number on the ruler
  5. Repeat 2-3 times
  6. After PERSON 1 and PERSON 2 have completed it , change a factor (caffein,alcohol)
  7. Record results
  8. Use conversion table to convert ruler measurements to reaction time.
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11
Q

List 3 control variables of reaction time practical

A

• person catching ruler uses DOMINANT hand
• drop same ruler from same height
• if investigating effect of caffeine, make sure there’s no alcohol consumption before

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12
Q

What is the eye function?

A

Sense organ containing receptors sensitive to light/ colour

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13
Q

structure of eye and function? (6)

A

CORNEA: transparent lens that refract light as it enter eye
IRIS: control how much light enter pupil
LENS: transparent disc that can change shape to focus light on retina
RETINA: contains LIGHT RECPETORS/COLOR RECPETORS
OPTIC NERVE : sensory neurone that carry impuses between eye to brain
PUPIL : hole that allows light to enter eye

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14
Q

in dim light what happen to eye?(3)

A

-pupil DILATES (WIDENS)
-radial muscle CONTRACT
-circular muscle RELAX

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15
Q

BRIGHT LIGHT what happens to eye?(3)

A

-pupil constricts
-radial muscles RELAX
-circular muscle CONTRACTS

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16
Q

what is accommodation?

A

process of changing shape of lens to focus on near/far objects

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17
Q

what happens to eye when focusing on near objects?(3)

A

-ciliary muscles CONTRACT
-suspensory ligaments LOOSEN
-lens is thicker/refracts light more

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18
Q

what happens to eye when focusing on far objects ? (3)

A

-ciliary muscles relax
-suspensory ligaments TIGHTEN
-Lens is THINNER/slightly refracts light

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19
Q

cause and solution of MYOPIA?

A

CAUSE -lens is too curved/thick
-image is in focus IN FRONT of retina

SOLUTION : CONCAVE LENS corrects rays so they focus on the retina

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20
Q

cause and solution of HYPEROPIA?

A

CAUSE- lens is too flat /light is focused BEHIND RETINA

SOLUTION: CONVEX LENS refracts light rays to focus on retina

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21
Q

advantages + disadvantages of
TREATMENTS FOR HYPEROPIA/MYOPIA?
Laser eye
Contacts
Lens replacement

A

HARD/SOFT CONTACT LENSES: sit on surface of eye
ad : ideal for sports /comfy
dis: risk of infection

LASER EYE SURGERY: change shape of cornea
dis : risk of unexpected damage

LENS REPLACEMENT SURGERY: replace lens with plastic,artifical one
dis: invasive
-risk of damage occurring to retina (complete sight loss)

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22
Q

functions of regions in brain?

A

CEREBRAL CORTEX: outer layer of brain divided in 2 hemispheres for INTELLIGENCE, MEMORY,CONSCIOUSNESS,
PERSONALITY, LANGUAGE

CEREBELLUM: -under cerebral cortex - BALANCE, MUSCLE COORDINATION,MOVEMENT

MEDULLA: controls unconscious activities like heart rate/breathing

23
Q

why are there difficulties in understanding the brain /treatment options?

A

very complex /delicate organ
any potential treatment could lead to further damage (speech ,personality changes etc)

24
Q

electrical stimulation of brain process?

A

tiny electrodes pushed into different parts of brain
-tiny jolts of electricity stimulate regions /effects can be observed

25
Q

MRI SCAN/functional MRI scans uses?

A

uses magnetic fields to study brain/ the effect these have on protons in water molecules in body
- functional MRI scans produce images of different images of brain that are active during different activities (active region shave increased blood flow)

26
Q

what is homeostasis ?

A

regulation of internal conditions of a cell/organism to maintain optimum conditions for function in response to internal/external changes.

27
Q

How does the pancreas respond when blood glucose levels are too low?

A

The pancreas secretes the hormone glucagon. Glucagon binds to liver cells,stimulating the liver into converting stored glycogen back into glucose. This glucose will be released into the blood, raising the blood glucose level back to normal.

28
Q

Describe the sequence of hormone interactions in the menstrual cycle

A

Fsh is released by the pituitary gland and this will cause the maturation of an egg ( in a structure called a follicle)in the ovary which will stimulate the ovaries to produce oestrogen. This will thicken the lining of the uterus and stimulate the release of LH ( from the pituitary gland) which causes the release of an egg (ovulation) and will inhibit the release of FSH. Once ovulation has occurred, progesterone will be released from the ovaries (by the remains of a follicle). This hormone will maintain the lining of the uterus during the second half of the cycle. If the egg is not fertilised, progesterone levels fall and the lining breaks down (period).

29
Q

How does the contraceptive pill prevent pregnancy?

A

-Inhibits FSH so eggs do not mature
-Prevents the development of the uterus lining so eggs cannot implant
-Increases the thickness of the cervical mucus immobilising sperm cells.

30
Q

How does the contraceptive injection, implant and patch work to prevent pregnancy?

A

It releases a continuos amount of progesterone, which stops the ovaries from releasing eggs, making it hard for sperm to swim to egg and stops any fertilised egg implanting in the uterus. Can last number of months or years.

31
Q

Describe the process of IVF

A

1) mother is given FSH and LH to stimulate the maturation of several eggs
2) eggs are collected from mother and fertilised by sperm in a laboratory
3) fertilised eggs develop into embryos
4) once the embryos are tiny balls of cells, one or two of them are transferred to the women’s uterus

32
Q

What are the roles of adrenaline and thyroxine?

A

1)Adrenaline (FIGHT OR FLIGHT)-
A hormone released by adrenal glands in times of fear or stress. It increases heart rate and boosts the delivery of oxygen and glucose to the brain and muscle preparing body for ‘fight or flight’.

2)Thyroxine (metabolism)-
Hormone released from the thyroid gland stimulating the basic metabolic rate. It plays an important role in growth and development.

33
Q

What are the purposes of:
-Gibberellins
-Ethene

A

Gibberellins are important in stimulating seed germination, stem growth and flowering.
Ethene controls cell division and ripening of fruits.

34
Q

What is phototropism?

A

Phototropism is the response of a plants root or shoot to the light.

35
Q

What is gravitropsim?

A

Gravitropism is the response of a plants root or shoot to gravity.

36
Q

What is auxin?

A

Auxin is a hormone which controls the growth of a plants root or shoots. When auxin is unevenly distributed, the rate of growth will be unequal.

37
Q

How do plants shoots show positive phototropism?

A

One side of the shoot is light, auxin accumulates on the shaded side

At the shaded side, the cells are stimulated to grow faster, causing the shoot to bend towards light

This means photosynthesis can occur at a faster rate

38
Q

How do plant roots show positive gravitropism?

A

In a horizontal root, auxin accumulates in the lower side, causing the cells to grow LESS. The root bends in the direction of gravity. This means more water and nutrients are available for the plant roots.

39
Q

How do plants shoots show negative gravatropism?

A

In a horizontal shoot, auxin accumulates on the lower side due to gravity. Cells on the lower side grow more, causing shoot to bend away from ground. This means more light is available for photosynthesis.

40
Q

Give three uses of auxins:

A

1) weed killers- auxin causes cells to grow at rapid rate causing death
2) rooting powder- auxin causes new plant to grow very quickly
3) tissue culture- auxin promotes growth at roots and shoots.

41
Q

What is type 1 diabetes?

A

A disorder in which the pancreas fails to produce sufficient insulin. Blood gluc levels can quickly rise.
(This is is because the immune system antibodies attacks and destroys these cells)

42
Q

What is type 2 diabetes?

A

A disorder where the body no longer responds to insulin produced by the pancreas.This prevents the conversion of glucose into glycogen and blood gluc levels remain high.

43
Q

Explain the effect on cells of osmotic changes in body fluids

A

Water leaves body via lungs during exhalation.
Water, ions and urea are lost from skin in sweat.
Excess water, ions and urea are removed via kidneys in the urine.

44
Q

Describe how the kidneys maintain the balance of water and other substances in the body?

A

1) FILTRATION- kidneys filter the blood to remove waste products (eg urea)
2) SELECTIVE REABSORPTION- kidneys reabsorb useful substances such as glucose, ions(some) and water
3) EXCRETION- removes all toxic urea and excess water and salts, leaving the correct concentrations in the blood.

45
Q

What is kidney dialysis?

A

A temporary medical treatment for kidney failure patient where blood is removed from the body, filtered and replaced.

46
Q

How are excess amino acids excreted from the body ?

A

Excess amino acids are deaminated in the liver to form ammonia
Ammonia is toxic, therefore it is converted into urea
Urea is excreted from the body via sweat and urine

47
Q

How does ADH affect the re absorption of water in the kidneys?

A

When blood is too concentrated ADH is released by the pituitary gland.
ADH travels in the bloodstream to the kidney and increases the permeability of kidney tubules to water.
More water is re absorbed in kidneys, resulting in a smaller volume of more concentrated urine.

48
Q

What is accommodation?

A

The changing shape of the lens in your eye to focus on a near or far object

49
Q

How does the lens change when focusing on a far object?

A

Ciliary muscles relax
Suspensory ligaments TIGHTEN
Lens becomes thinner

50
Q

How does the lens change when focusing on a close object ?

A

Ciliary muscles contract
Suspensory ligaments LOOSEN
Lens becomes thicker

51
Q

What lens can be used to fix long sightedness and how

A

A convex lens
Light rays bend more inwards

52
Q

What lens can be used to fix short sightedness

A

A concave lens
Light rays bend less

53
Q

How does someone’s eye adjust to form a clear image of a nearer image?6 marks

A

Ciliary muscles CONTRACT meaning diameter decreases and Suspensory ligaments loosen. This means the lens thickens and is more convergent and light rays will focus on retina

54
Q
A

Biology (5 decks)

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