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Biology > 5-Homeostasis and response (2) > Flashcards

5-Homeostasis and response (2) Flashcards

1
Q

What is the role of the cereba cortex?

A

Controls intelligence, consciousness, memory and language.

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2
Q

What is the role of the cerebellum?

A

Controls muscular activity and balance.

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3
Q

What is the role of the medulla?

A

Controls unconscious activity e.g such as heart beat, breathing, digestion.

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4
Q

What is the role of the Lens?

A

Focuses the light rays by refraction onto the retina.

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5
Q

What is the role of the Cornea?

A

Protects the front of the eye and helps to focus the light.

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6
Q

What is the role of the Iris?

A

Made of muscle that can increase or decrease pupil size.

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7
Q

What is the role of the Pupil?

A

Gap between iris that allows light to reach the retina.

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8
Q

What is the role of the Retina?

A

Contains light-sensitive cells that receive an image and pass it to the brain.

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9
Q

What is the role of the Suspensory ligaments?

A

Hold the lens in position.

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10
Q

What is the role of the Ciliary muscles?

A

Contract to stretch the lens and relax to make the lens rounder.

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11
Q

What is the role of the Sclera?

A

Tough outer coating of the eye.

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12
Q

What is Myopia?

A

*Short-sightedness
*Caused by lens too round or long eyeball
*treated by concave lens glasses

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13
Q

What is hyperopia?

A

*Long-sightedness
*Cause by lens to flat or eyeball too short
*Fixed by convex lens glasses

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14
Q

How do the eyes adjust to bright light?

A

*Circular muscles contract
*Radial muscles relax
*Pupil constricts

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15
Q

How do eyes adjust to dim light?

A

*Circular muscles relax
*Radial muscles contract
*Pupil dilates

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16
Q

How do the eyes focus on near objects?

A

*Ciliary muscles contract
*Suspensory ligaments loosen
*Lens is then thicker and refract
*Light rays strongly

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17
Q

How do the eyes focus on distant objects?

A

*Ciliiary muscles relax
*Suspensory ligaments pulled tight
*Lens pulled thin and only slightly refracts light

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18
Q

How are lenses when they are relaxed?

A

*Lens spring, unless pulled will be fat
*Fat lenses refract more light

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19
Q

Describe the reflex arc?

A

Stimulus–> Receptor –> Coordinator –> Effector–> Response

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20
Q

What is the reflex arc?

A

Transmission of a nerve impulse from a receptor to the central nervous system and effector, to bring about a response to a stimulus.

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21
Q

How do scientists use patients with brain damage to study the brain?

A

*Study patients with brain damage-you can tell what area is damaged by the affect it has.

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22
Q

How do scientists use electronic stimulation of the brain to study it.

A

Pushing a tiny electrode into the tissue and giving it a small zap of electricity and observing the effects of different areas being stimulated.

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23
Q

How do scientists use MRI scans to study the brain?

A

It produces a very detailed picture of the brain’s structure to find out what areas are active during certain activities.

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24
Q

What are the problems with studying the brain?

A

*Incredibly complex and delicate
*Risks physical damage to the brain or problems with brain fuction.

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25
Q

How is body temperature controlled when body is too hot?

A

*Temperature receptors detects that the body is too hot
*Thermoregulatory centre acts as coordination centre, receiving information from the temperature receptors and triggers effectors automatically
*Effectors produce a response to counteract change

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26
Q

How is body temperature controlled when the body is too cold?

A

*Temperature receptors detect temperatures are too low
*Thermoregulatory centre acts as a coordination centre, receiving information from temp receptors and triggers effectors automatically
*Effectors produce a response and counteract change

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27
Q

How does the body cool itself down?

A

*Sweat produced by sweat glands and evaporates from skin, transferring energy to the environment
*Blood vessels supplying the skin dilate so more blood flows close to the surface to transfer energy from skin to environment (vasodilation)
*Hairs lie flat to allow heat to transfer to surroundings

28
Q

How does the body warm itself up?

A

*No sweat produced
*Blood vessels constrict to prevent transfer of heat to the surroundings (vasocontriction)
*Hairs erect to trap an insulating layer of air
*Shiver to produce thermal energy from respiration of muscles

29
Q

What is the endocrine system?

A

Sending chemical messengers known as hormones around the body via the bloodstream

30
Q

What is the role of the pituitary gland?

A
  • Produces many hormones that regulate body conditions
  • sometimes called the ‘master gland’
  • stimulates other glands
31
Q

What is the role of the thyroid gland?

A
  • Produced thyroxine
  • regulating rate of metabolism, heart rate and temperature
32
Q

What is the role of the adrenal gland?

A
  • produces adrenaline
  • prepares for ‘fight or flight’ responses
33
Q

What is the role of the pancreas?

A
  • produces insulin
  • used to regulate blood glucose levels
34
Q

What is the role of the ovaries?

A
  • produce oestrogen
  • involved in menstrual cycle
35
Q

What is the role of the testes?

A
  • produces testosterone
  • controls puberty and sperm production
36
Q

What is the difference between hormones and nerves?

A
  • nerves very fast - hormones much slower
  • nerves act for short tie - hormones act for long time
  • nerves act on a very precise area - hormones act in a more general way
  • nerves are electrical impulses - hormones diffuse through blood
37
Q

How does the body respond when blood glucose is too high?

A
  • insulin secreted by pancreas
  • glucose moves from blood into liver and muscle cells
  • insulin makes liver turn glucose into glycogen
38
Q

How does the body respond when blood glucose is too low?

A
  • glucagon secreted by pancreas
  • but glucagon as well
  • glucose released into blood by liver
  • glucagon makes liver turn glycogen into gluucose
39
Q

How are water levels maintained in the body?

A
  • Water leaves body via lungs during exhalation
  • water, ions and urea are lost from the skin in sweat
  • no control over loss by the skins or lungs
  • excess water, ions and urea removed via kidneys in the urine
40
Q

How the kidney’s remove urea?

A
  • proteins and amino acids can’t be stored by the body so any excess amino acids are converted into fats and carbohydrates in the liver, which can be stored
  • ammonia produced as a waste product
  • ammonia is toxic so converted to urea in the liver
  • urea transported to kidneys where filtered out of blood and excreted as urine
41
Q

How do the kidney’s remove ions?

A
  • ions such as sodium taken in by food and absorbed into blood
  • if ion content wrong, could upset balance between ions and water, meaning more or less water drawn in or out of the cell by osmosis
  • some ions lost in sweat which is not regulated so balanced must be maintained by the kidneys
42
Q

Why is kidney failure so dangerous?

A

Kidneys remove waste substances, waste substances build up and lose ability to control water and ion levels

43
Q

How does dialysis work?

A
  • blood flows between partially permeable membrane surrounded by dialysis fluid
  • dialysis fluid contains same concentration of dissolved ions and glucose as healthy blood so no ions or glucose lost
  • only waste substances such as urea and excess ions and water diffuse across
44
Q

What are the disadvantages of dialysis?

A
  • need sessions 3 times a week
  • each session takes 3-4 hours
  • may cause blood clots or infections
  • more expensive in the long run
45
Q

How do kidney transplants work?

A
  • healthy kidneys usually transplanted from someone who has died suddenly
  • kidneys can also be transplanted from people still alive
46
Q

What are the disadvantages of kidney transplants?

A
  • can be rejected by immune system
  • need to take immunosuppressants to minimise risk of rejection which can cause other illnesses
  • long wait
  • risk to person donating
47
Q

What is stage 1 of the menstrual cycle?

A
  • menstruation starts and uterus lining breaks down for about 4 days
48
Q

What is stage 2 of the menstrual cycle?

A

Uterus lining builds up again - from day 4 to 14 into thick spoungy layer of blood vessels to prepare for egg

49
Q

What is stage 3 of the menstrual cycle?

A

An egg develops and is released from ovary at day 14 - ovulation

50
Q

What is stage 4 of the menstrual cycle?

A

Wall is maintained for about 14 days until day 28 - if no fertilised egg received lining breaks down

51
Q

What are the 4 hormones involved in the menstrual cycle?

A
  • FSH
  • Oestrogen
  • LH
  • Progesterone
52
Q

What is the role of FSH in the menstrual cycle?

A
  • produced in pituitary gland
  • causes egg to mature in one of the ovaries as a follicle
  • stimulates ovaries to produce oestrogen
53
Q

What is the role of Oestrogen in the menstrual cycle?

A
  • produced in the ovaries
  • causes lining of the uterus to grow
  • stimulates the release of LH (which causes egg release) and inhibits release of FSH
54
Q

What is the role of LH in the menstrual cycle?

A
  • produced by the pituitary gland
  • stimulates release of egg at day 14
55
Q

What is the role of Progesterone in the menstrual cycle?

A
  • produced in ovaries by the remains of follicule after ovulation
  • maintains lining of the uterus during second half of cycle - when progesterone levels fall, lining breaks down
  • inhibits release of LH and FSH
56
Q

How can hormones be used to reduce fertility?

A
  • Oestrogen used to prevent release of egg as level kept permenantly high and inhibits FSH
  • Progesterone causes thick mucus that prevents sperm reaching egg
  • can be used as pill, patch, implant or IUD
57
Q

How can barriers be used as contraception?

A
  • stop sperm meeting egg
  • condoms prevent sperm meeting egg and are the only contraception that protect against STD’s
58
Q

How is sterilisation used to avoid pregnancy?

A
  • cutting or tying fallopian tubes or sperm ducts - permenant procedure
59
Q

Natural methods of contraception

A
  • only having intercourse in the least fertile sections of cycle
60
Q

What is the role of auxin?

A
  • plant growth hormone
  • controls growth near tips of shoots and roots
  • controls growth in response to light (phototropism) and gravity (gravotropism)
61
Q

How does auxin affect the shoots?

A
  • shoot grows towards light
  • when shoot tip exposed to light more auxin accumulates on the side that’s in the shade so shoot bends towards light - when a shoot growing sideways, gravity produces unequal distribution of auxin in the tip with more auxin on lower side
  • lower side grows faster with more auxin on lower side
62
Q

How does auxin affect roots?

A
  • root growing sideways always has more auxin on lower side
  • in a root extra auxin inhibits growth so cells on top elongate faster and root bends downwards
63
Q

How can auxins kill weeds?

A

disturb normal growth patterns of broad-leaved plants which soon kills them

64
Q

How can auxins cause growth from cuttings with rooting powder?

A
  • add rooting powder and stick in soil - produce roots rapidly that start growing as new plants
  • produce lots of clones very quickly
65
Q

How can auxins be used to grow cells in tissue cultures?

A
  • auxins added to growth medium to stimulate cells to divide
66
Q

How can gibberelins be used?

A
  • Controlling dormancy - make them germinate at different times of the year they normally wouldn’t
  • Inducing flowering - flower without changes in environmental conditions
  • Growing larger fruits
67
Q

How can ethene be used in plants?

A
  • influences growth of plant by controlling cell division and stimulates enzymes that cause fruit to ripen
  • fruit can be picked unripe and ripened using ethene on the way to shops
  • can also be delayed with chemicals that block ethenes effect

Biology (17 decks)

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