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homeostasis Flashcards

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1
Q

what is adrenaline:

A

prod by adrenal glands
located above kidney
in response to stress or scary situations, brain triggers release of adrenaline

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2
Q

what does adrenaline do:

A

-increases heart rate
-boosts delivery of oxygen and glucose to brain and muscles, preparing for fight or flight
-Increases blood pressure
-causes conversion of glycogen to glucose

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3
Q

what is thyroxine:
-location
-stimulates ____

A

-released from thyroid gland
-incr. basal metabolic rate; (speed at which chemical reactions occur when body at rest)
-stimulates protein synthesis in cells,
-important for growth and development

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4
Q

negative feedback in thyroxine levels
-if levels too high
-if levels too low

A

level of thyroxine too high;
-release of TSH inhibited, less thyroxine released from thyroid gland

level of thyroxine falls below a norm level,
-release of TSH from pituitary increased, stimulates thyroid to release more thyroxine

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5
Q

what happens if homeostasis is not met?

A

-enzymes start to denature (change shape)
-this reduces their ability to catalyse metabolic reactions

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6
Q

what are neurotransmitters?

A

neurotransmitters are chemicals that diffuse across synapses and bind to receptors on the next neurone

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7
Q

describe process of reflex action:

A

-stimulus detected by receptor (ex. sharp object)
-electrical signals sent to sensory neurone
-sensory neurone sends signal to spinal cord -> s.c processes signal
-signal travels as chemical message through neurones via synapse (through diffusion)
-relay neurons send electrical signals from s.c to effector (ex. leg) via motor neuron
-reaction is carried out

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8
Q

describe how body responds when a decrease in core body temp detected:

A

-blood vessels that supply skin constrict, less blood flow to skin (vasoconstriction)
-less energy lost to surroundings
-(shivering) muscle contraction generates heat by releasing more energy; respiring more

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9
Q

why protein is not found in the urine of a healthy person:

A

-protein molecules too large to pass kidney filters
-body needs proteins
-kidneys developed to ensure that

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10
Q

why is glucose not found in the urine of a healthy person:

A

-they only appear if blood sugar levels too high
-body needs to make use of glu for respiration therefore it is completely reabsorbed into blood

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11
Q

explain
-why urea and sodi ions found in urine
-why their concen is higher on a hot day than a cold day

A

-urea made in liver when excess amino acids broken down, main waste product, not reabsorbed into kidney
-sodi and urea both small enough to pass filters
-con is higher as more water lost through sweat, so less water passed out as urine

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12
Q

pathway of a reflex arc

A

-stimulus
-receptor
-sensory neurone
-relay neurone
-motor neurone
-effector
-response

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13
Q

name the two types of effectors and state what they do

A

muscles contracts
glands release hormones

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14
Q

features of a nervous system

A

-very fast/precise
elec impulses thru nerves
-respond quickly

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15
Q

features of endocrine system

A

-release hormones (bloodstream)
-across entire body, but only affect certain cells with right receptors
-more generalised, slower,, longer lasting

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16
Q

response to stimuli that involve directional (towards grav) growth:

A

geotropism

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17
Q

what is ethene

A

a gas that controls cell division and the ripening of fruits

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18
Q

what is giberellins

A

are important in starting off the seed germination (sprouting) process

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19
Q

response to stimuli that involve directional (towards light) growth:

A

phototropism

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20
Q

In ……., auxins promote the elongation of cells.
However, in ……., auxins ……. the elongation of cells.

A

-shoots
-roots, prevent

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21
Q

Tropisms are controlled by …….. They are groups of responses that can be split into …..tropisms and …..tropisms.

A

-auxins
-photo, geo

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22
Q

how does hypothalamus send signals across body

A

neurones

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23
Q

advantages of kidney transplant

A
  • no need for regular / long hospital visits or is a long-term
    solution
  • flexible lifestyle, such as can go on holidays
  • may not live near a hospital or reference to transport costs
  • no risk of infection from frequent needles / treatment
  • less / no need to control diet
  • maintains correct concentration of substances in blood / body
  • cheaper long term for hospital
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24
Q

disadvantages of kidney transplant

A

😭 may be rejected
* have to keep taking anti-rejection drugs or
immunosuppressants
* (suitable) donor may not be available or need for tissue
matching
* risk from surgery (e.g. anaesthesia or infection)
* recovery from surgery will take a long time
* does not last forever (therefore further surgery needed)

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25
Q

Marathon runners often drink sports drinks during a race.
Explain why.

A

to replace water / ions / salt
(that is) lost in sweat

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26
Q

describe retina

A

-Layer of light sensitive cells found at the back of the eye.
-When light hits this, the cells are stimulated. Impulses are sent to the brain, which interprets the information to create an image.

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26
Q

describe cornea

A

-The see-through layer at the front of the eye.
-It allows light through and the curved surface refracts and focuses light onto the retina.

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27
Q

describe sclera

A

White outer layer which supports the structures inside the eye.
It is strong to prevent some damage to the eye.

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28
Q

describe optic nerve

A

-A nerve that leaves the eye and leads to the brain.
-It carries the impulses from the retina to the brain to create an image

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29
Q

what is a cone cell

A

-a receptor cell
-detects color
-doesn’t work well in low light

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30
Q

what is a rod cell

A

-a receptor cell
-more sensitive to light
-can only see in black and white

31
Q

what is iris

A

-Muscles that surround the pupil
-They contract or relax to alter the size of the pupil.

32
Q

what is the fovea

A

a region on the retina where there’s only cone cells
-this region that we try to focus light on (+ clear)

33
Q

what is the cerebral cortex responsible for

A

-consciousness
-intelligence
-memory
-language
-senses

split into two hemispheres, left side cont. right side of body, vice versa

34
Q

what is the cerebellum responsible for

A

-balance
-muscle coordination

35
Q

what is the hypothlamus responsible for

A

-regulating body temp
-sends signals to pituitary gland

36
Q

what is the medulla responsible for

A

-found in brain stem
controls unconscious activities, ie breathing, beating of our hearts

37
Q

how scientists study brains

A

-study peeps w/ brain damage
-elect stimulate diff parts of the brain w/ electrode
-scanning brain (MRI, CT)

38
Q

in shoots, auxins …… growth, in roots, it …….. growth

A

-stimulate
-inhibit

39
Q

auxin accumulates on the ……. side (shoot) and the …….. side (root)

A

-shaded
-lower

40
Q

auxin stimulates….. inhibits…..

A

-growth in shoots
-growth in roots

41
Q

thyroxine is released in response to ……… which is released from …….. …..

A

-thyroid stimulating hormone (TSH)
-pituitary gland

42
Q

Describe what will happen when thyroxine levels are too high.

A

If thyroxine levels too high, thyroxine will inhibit the pituitary gland from prod. TSH.

TSH stimulates thyroid gland to prod. thyroxine, so less TSH means the thyroid gland won’t release as much thyroxine, and so over time thyroxine levels in the blood fall back to normal. (negative feedback.)

43
Q

Iris muscles during bright and dim light

A

In bright light,
circular muscles contract, radial muscles relax
:pupil smaller

In dim light,
circular muscles relax, radial muscles contract
:pupil larger

44
Q

mnemonic for iris in bright/ dim light

A

bright:
BLCCRR

dim:
DLCRRC

45
Q

when looking at close object lens needs to be….

A

short and fat (+curved)

46
Q

when looking at far object lens needs to be….

A

long and thin

47
Q

mnemonic for close object on lens

A

COSFCCSS

close object short fat ciliary contract suspensory slacken

48
Q

mnemonic for far object on lens

A

FOLTCRST

far object long thin ciliary relax suspensory taut

49
Q

long sighted (hyperopia) , lens ….. ….. enough.
fixed using …. lenses

A

-can’t refract
-convex

50
Q

short sighted (myopia) , lens refracts ….. … ……. .
fixed using …. lenses

A

-light too much
-concave

51
Q

can suspensory ligaments contract & relax

A

-no
-they are ligaments not muscles

52
Q

what is homeostasis

A

It is the maintenance of a constant internal environment despite changes in internal and external conditions.

53
Q

What is the role of receptors in the body?

A

To detect changes in conditions

54
Q

Temperature receptors are found throughout the body.
Where are the two main places they’re found?

A

Blood vessels
Skin

55
Q

desc protein synthesis

A

-proteins made on ribosomes in cytoplasm
-ribosomes use code from DNA, but DNA too big to fit through the nucleus so
-mRNA copies the DNA code and transfers it to the ribosomes (only a single gene and single strand so small enough to pass through)
-correct amino acids brought by carrier molecules (tRNA) in correct order to the ribosomes

56
Q

what happens if blood glucose levels are too low

A

if too low:
-pancreas releases hormone glucagon
-this travels up to the liver in the blood and causes breakdown of glycogen into glucose
-glucose enters b.stream, levels back to normal again

57
Q

What happens if glucose levels are too high?

A

● If the glucose levels are too high, the pancreas produces the hormone insulin
● Insulin binds to cells in target organs (muscles and liver) causing:
○ 1) Glucose to move from the blood into muscle cells for respiration
○ 2) Excess glucose to be converted into glycogen which is stored in the liver
● The blood glucose concentration is reduced

58
Q

liver and muscle cells take up glucose and combine them together to form

A

glycogen, a long term storage for glucose

59
Q

What happens if blood glucose concentrations fall too low?

A

There won’t be enough glucose for tissue cells to respire

60
Q

type 1 diabetes:
occurs…
lasts..
because of…

A

childhood and teenage
lifelong
pancreas stops prod insulin / tiny amounts
glucose level can rise rlly high
main treatment injections of insulin into abdomen or thigh
after meal

61
Q

type 2 diabetes
occurs…
how…
because of…

A

generally happens to older people w unhealthy diets for long time
persons cells resistant, don’t respond to insulin anymore
cells wont take glucose from bloodstream
treatment: healthy low sugar diet, exercise

62
Q

How can oestrogen act as a contraceptive?

A

Inhibit FSH production, so that eggs can’t mature

63
Q

How can progesterone act as a contraceptive?

A

Stimulate the production of mucus in the cervix, so sperm can’t enter the uterus

64
Q

Describe how the brain receives information about light entering the eye.
You should include the names of structures in your answer

A

-retina sensitive to light
-impulse passes along (sensory) neurone
-(along) optic nerve

65
Q

describe the process of filtration in the kidneys

A

-as the blood passes through the kidneys in the tubules, the blood in the capillaries absorbs anything small:
water, glucose, amino acids, urea
-as it passes through, the useful stuff is reabsorbed back into the blood such as
-all glucose, some water (selective reabsorbtion)

66
Q

where is urea made
..process..

A

in the liver during the process of ‘deamination’, which is when excess amino acids are converted to fats and carbohydrates for storage

67
Q

what happens when water levels are too low

A

-hypothalamus to detects the concentration of water in the bloodstream too low
- signals sent to the pituitary gland
- stimulates release of ADH
- kidney reabsorb more water, so less urine prod.

68
Q

how does dialysis work

A

-blood goes through dialysis machine, through partially permeable membrane so small molecules can diffuse across to dialysis fluid (same conc. of water and other molecules as healthy blood)
-blood goes back to patient, no urea
-as equilibrium reached, new fluid pumped in, old out
-so there’s always a conc. gradient

69
Q

problems w/ dialysis

A

-time consuming
-can cause blood clots, infection
-expensive to run
-needed for rest of life

70
Q

stages of menstrual cycle

A

-stage 1, till day 4: period of bleeding; breakdown of uterus lining
-stage 2 till day 14: uterus lining starts to build up again, to prepare uterus lining for fertilised egg
-stage 3: ovulation at day 14: egg being released
-stage 4: till day 28; maintains lining of uterus
no fertilised egg means cycle happens again

if fertilised egg, lining keeps on building, no more cycle

71
Q

if progesterone levels drop…

A

uterus lining breaks down, cycle restarts

72
Q

what does oestrogen do ?

A

stimulates uterus lining to grow, increases in stage 2

73
Q

which reproductive hormones are produced in the ovaries and pituitary gland

A

ovaries:
oestrogen, progesterone

pituitary:
LH, FSH

74
Q

interaction of hormones in menstrual cycle

A

FSH stimulates maturation of egg and release of oestrogen from ovaries

oestrogen inhibits FSH production, stimulates LH production

LH stimulates ovulation

progesterone inhibits FSH and LH production

oestrogen and progesterone maintain the uterus lining

biology: paper 2 (3 decks)

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