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Homeostasis Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

what is homeostasis?

A

Homeostasis is the regulation of the body’s internal conditions to maintain the optimal conditions for enzyme action and cell function.

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2
Q

What is a stimulus?

A

A change in the environment (triggers receptors)

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3
Q

What are the 3 main components of an automatic control system?

A

Receptors
Cns( control centres)
Effectors

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4
Q

What are the five independent components of control mechanisms that respond to change and how do they do it.

A

-reference point-the desired level (“norms”)at which the system
operates
- receptor-monitors + responds to changes in the environment (the stimulus)
control centre (coordination)-analyses information from receptor.;determines
appropriate response.
Effector-supplies means to respond to stimulus (i.e. generates a response
to the change in the internal environment)
Feed back loop-informs receptors of the changes to the system brought about
by the effector.

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5
Q

WHAT ARE RECEPTORS?

A

cells that detect change in the enviroment

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6
Q

What are effectors?

A

Muscles or glands that carry out a response

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7
Q

What are coordination centres?

A

Areas that receive and process info. They coordinate a response

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8
Q

what is a concious action?

A

an action that is thought about

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9
Q

what is an unconscious action?

A

an action that is not thought about it is a reflex action which involved brain or nerves.

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10
Q

what are nerve fibres

A

bundles of nerve cells(neurones) that pas on electrical signals (impulses) to the brain. From the brain , nerve fibres send impulses to the effectors

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11
Q

what does motor neurone do?

A

carries electrical impulses from the cns/ brain to the effector

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12
Q

What does the sensory neurone do?

A

Carry impulses from the sense organ to the central nervous system

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13
Q

how do the sensory neurojne motor neurone and cns work together?

A

Neurones carry electrical impulses are carried from the sense organ to the cns where information is processed, and impulses are sent along the motor nerves to produce an action in the effectors.

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14
Q

CNS vertabraes v mamals

A

Central nervous system
. In vertebrates(animals with backbones) this consists of the brain and sppinal cord only . In mamals(humans etc#), the cns is connected to the body by sensory neurones and motor neurones.

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15
Q

What is the CNS(Cebtal Nervous System)?

A

the coordination centre, it receives info from the receptors and then coordinates a response (decides what to do about it. The response is carried out by the effectors.

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16
Q

what are reflex actions?

A

Automatic responses to stimuli

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17
Q

sequence in a reflex arc

A

stimulus
stimulaytes receptor
impulses travel along sensory neurone
then a synapse to a relay neurone
then a synapse to the motor neurone then motor neurone is connected to effector so impulses got to effector causing a reflex action.

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18
Q

how do synapses work?

A

Synapses are connections between two neurones that have a gap in between. Impulses arrive at the neurone and are transferred into sacs of chemicals which are then released into the gap between the neurones and diffuse (these chemicals are called neurotransmitters). The neurotransmitters attach to the surface of the next neurone at the receptor site. and set up a new electrical impulse

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19
Q

Reaction time method (Required Practical)

A

Work with a partner.
Person A holds out their hand with a gap between their thumb and first finger.
Person B holds the ruler with the zero at the top of person A’s thumb.
Person B drops the ruler without telling Person A and Person A must catch it.
The distance on the ruler level with the top of person A’s thumb is recorded in a suitable table.
Repeat this ten times.
Swap places, and record another ten attempts.
You can use the conversion table to help convert your ruler measurements into reaction time or just record the catch distance in cm.

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20
Q

What are the methods scientists use to study the brain?

A

-studying Patients with Brain damage-If small
part of the brain has been damaged.the effect
this has on the patient can tell what the damaged
part of the brain does(function)

-electrically stimulating the brain-the Brain can
be stimulated by pushing a tiny electrode into th
tissue and zapping it with electricity. by observing
what stimulating different parts of the Brain does its
possible to get an idea of what those parts do.
E.g. motor neurone stimulated-it causes muscle contraction
and movement.

MRI Scans-Magnetic resonance imaging (MRI)
scanner is a big fancy tube-like machine
that can produce a
detailed picture of the
brain’s structures, scientists
use it to find out what
areas of the brain are active
when people are doing things such as
listening to music or
trying to recall a memory

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21
Q

How did Phinneas Gage help with the discovery of the brains functions?

A

Phineas Gage
-railway worker who was injured by
an iron spike
It destroyed most of his frontal lobe
He survived but his personality was very
different from before
conclusion
Frontal lobes of the brain are important for
controlling personality.

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22
Q

What does the Cerbral Cortex do?

A

The outer wrinkly bit which is responsible for things like intelligence, consciousness, memory and language

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23
Q

What does the medulla do ?

A

Controls unconscious activities such as heart beat and breathing

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24
Q

What does the cerebellum do ?

A

Responsible for muscle coordination + movement +balance

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25
Q

What does the hypothalamus do?

A

The hypothalamus regulates the bodies temperature as well as sending signals to the pituitary gland

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26
Q

What does the pituitary gland do?

A

The pituitary gland produces and secretes hormones e.g sex hormones, growth hormones, ADH

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27
Q

what do the ciliary muscles do ?

A

Involved in changing the shape of the lens

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28
Q

what does the iris do?

A

regulates the amount of light entering the pupil

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29
Q

What does the Cornea do?

A

Refracts light rays into the eye(as well as protecting the eyes surafce

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30
Q

what does the pupil do ?

A

a hole allowing light to enter the eye

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31
Q

ewhat does the lens do?

A

Focuses light on to the retina

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32
Q

What is the scelera( in terms of eyes)?

A

A though supporting wall of the eye

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33
Q

what doeds the optic nerve do ?

A

carries impulses from the receptors of the retina to the brain

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34
Q

What does the retina do ?

A

contains light receptors that sense light

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35
Q

What is the fovea?

A

area of the retina that provides the clearest vision

36
Q

How do eyes focus on near objects?

A

Looking at near objects
Ciliary muscles tighten
- suspensory ligaments relax
. The ciliary muscles contract which slackens
the suspensory ligaments.
-the lens becomes fat (more curved)
. this increases the amount by which it retracts light.

37
Q

What happens to the lens when focusing on distant object?

A

To look at distant objects
-ciliary muscles relax
-suspensory ligaments tighten
- the ciliary muscles relax which allows
the suspensory ligaments to pull tight.
-this makes the lens go thin(less curved)
-So it refracts light by a smaller amount.

38
Q

Describe and explain how the image is formed on the retina?

A

AThe light reaches your eyes from distant objects, travelling in almost parcelled rays. The cornea refracts the light entering the eyes towards the retina, but it is the lens that

39
Q

What are the two types of receptor cells in the retina and what do they do ?

A

cone cells-sensitive to colour
so allow us to see in colour.
( don’t work very well in low
light conditions)
rod cells-which are (more) sensitive
to light which allows us to see in
black and white. (thats why we can’t
see colours when its dark)

40
Q

The iris are made from two muscles what are they and what do they do

A

Radial muscles -They stretch from inside to outside like a radius.
Circular muscles . circular muscles that stretch round the pupil like circles

41
Q

How does iris reflex work(include radial and circular muscles in your explanation)?

A

very bright iight can damage retina
when light receptors in the eye detect very bright light,
a reflex is triggered. that makes the pupil smaller. the circular
muscles in the iris contract and the radial muscles relax.
This makes the pupal smaller and reduces the ammouny of
light that can enter the eye.
The opposite happens in dim light. The radial
muscles contract the circular muse us relax. therefore
making the pupils wider allowing more light into the eye

42
Q

what is hyperopia?

A

can focus clearly on distant objects but not near objects tjis is dueto the lens not being the rigjht shape or the eye being too short therefore the rays are refracted behind the retina

43
Q

What are contact lenses?

A

Thin lenses that you put on surface of eye to improve eyesight by compensating for fault focusing

44
Q

Pros of contact lenses

A

More convenient than glasses
Unnoticeable(relatively invisible)
Able to see better
Fairly cheap

45
Q

Cons of contact lenses

A

Higher risk of infection
May be uncomfortable especially if a hard lens

46
Q

What is laser eye surgery?

A

A laser vapouriest tissue changing the shape of the cornea by slimming it down or changing shape to focus light perfectly on the retina

47
Q

Pros of laser eye treatment

A

Better eyesight
Don’t need to wear glasses

48
Q

Cons of laser eye treatment

A

Expensive
Risk of complications
Higher risks of infections

49
Q

What is replacement eye surgery

A

The lens from the eye is replaced with an artificial a lens

50
Q

Pros of replacement lens surgery

A

Eye sight is improved
Don’t need to buy or wear glasses or contacts

51
Q

Cons of replacement lens surgery

A

Higher risk of damage to eye than laser eye surgery
Risk of losing sight
Risk of infections
Risk of damaging retina

52
Q

what do hormones control?

A

growth
sexual development
sugar level
mood
metabolism

Side note: they stabilise the bodies internal environment

53
Q

similarities between the ns and es

A

both monitor stimul98i and rect so as to maintain homeostasis

54
Q

differences between the ns and es

A

the ns is rapid fast-acting system whose effect does not always preserve
Ns is precise to an are Ed is more general

the es acts slower(via blood bone chemical signals called hormones0 anbd its actions are usually longer lasting
]

55
Q

What are hormones?

A

A chemical messenger that travels in the blood to activate target cells

56
Q

What do sex hormones do in boys?

A

Puberty
become muscular
- Grow facial + pubic hair
-voice breaks + becomes deeper
- testes produce sperm + genitals develop

57
Q

What doe sex hormones do in girls?

A

Puberty
Breast develop
Hips become wider
Pubic hair
Periods start

58
Q

What does the ovaries do as an endocrine gland?

A

ovaries -Females
-produce several hormones
↳ oestrogen
↳ controls development of female second,
sexual characteristics
‘regulates menstrual cycle
progesterone
↳ thickens uterine wall
-prevents contractions until the baby is being born

59
Q

What does the thyroid produce and do (endocrine gland/es)?

A

Thyroid
-produces hormone called thyroxine
↳ regulates rate of metabolism (main one)
- Heart rate
- deficiency causes overweight or sluggishness
-excess can cause hyperactivity.

60
Q

What does the adrenal glands produce and do?

A

Adrenal Glands
-produces hormone adrenaline
-adrenaline cause fight or flight response sresulting in:
Increases heart rate + breathing rate
blood diverted to the muscles
increases respiration to increases amount of guise in the
blood.

61
Q

What do the testes do and produce?

A

Testes-males
produces testosterone
↳ promotes development of male secondary characteristics
ie. controls puberty and sperm production
what do set hormones as in boys?
become muscular
- Grow facial + pubic hair
-voice breaks + becomes deeper
- testes produce sperm + genitals develop

62
Q

What does the pancreas do and produce? In terms of endocrine system

A

Pancreas
produce hormone insulin
↳ insulin controls blood glucose conc
Deficiency causes the condition’sugar diabetes’
where the blood sugar is unregulated.

63
Q

What does the pituitary gland produce and do?

A

Pituatry Gland
produces several hormones:
Growth hormone
promotes bone + muscular growth

Antidiuretic Hormone (ADH)
- controls reabsorption of water in the blood by
the kidneys.

Controls most endocrine glands

It also produces follicle stimulating hormone (FSH) and Luteinising Hormone (LH)

64
Q

What is glucose?

A

Glucose-a sugar used in respiration to make energy

65
Q

What is glycogen?

A

Glycogen-a storage(storage form of glucose)substance made
of glucose, it is stored in the liver and muscles(muscle cells)

66
Q

What is insulin?

A

Insulin-a hormone that tells your body to change glucose
into glycogen. It is made by the pancreas.

67
Q

What is glucagon?

A

Glucagon-a hormone that tells the liver to change glycogen
back into glucose. also made by the pancreas

68
Q

What is type 1 diabetes?

A

type 1(Insulin Dependent)-where pancreas produces little
or no Insulin. this means a persons blood glucose level
can rise to a level where it can kill them. then some
people with type 1 need insulin therapy (usually several
injections of insulin most likely at meal times

Develop very quickly over a few weeks

Managed by insulin and diet control

69
Q

What is ty

A
70
Q

What is type 2 diabetes?

A

Type 2 diabetes. when a person becomes resistant or less responsive to
their own insulin (still produce it)this can also cause a persons blood
sugar levels to rise to a dangerous level. usually develops later in life
and risk is increased through poor diet + obesity.

Managed by excercise and healthy diet

71
Q

Why does insulin need to be injected rather than digested?

A

Insulin is a hormone which is a protein

Digestive system breaks down proteins
Insulin would have little or no effect if digested

Being injected it can go straight into bloodstream and act straight away

72
Q

What is negative feedback?

A

Negative feedback-bodies response (corrective system) which restores a
level back to its optimum in a system

73
Q

Function of testosterone

A

major sex hormone responsible for the development of
male secondary sexual characteristics:
-enlargement of the penis + testes
- enlargement of the larynx or adams apple
-promotes the development of muscle tissue over fat
-stimulates growth of hair on the face,chest, under the
arms + around the genitals.

74
Q

What is tropism?

A

Tropism-a plants response to its environment

75
Q

What does the body do to become cold when it’s too hot

A

Thermoregulation centre coordinates response

sweat-evaporates-takes thermal energy with it
-vasodilation (blood flows close to surface
of the skin,
- Hairs sie stat

76
Q

What is normals body temp?

A

37 degrees celcius

77
Q

What does the body do when it’s too cold and needs to warm

A

Hairs stand up to war an insulating lager stain
-releasing energy from food
-no rattle sweat produced
- mood vessels sapping skin capillaries constrict (close at) to
prevent neat loss this is vasoconstriction
shivering-muscles release energy

78
Q

Danger of body temp too high

A

Enzymes denature

79
Q

Danger of body temp too low

A

Reactions are slower

80
Q

Advantages of barrier methods

A

no side as sects
offee some protection

81
Q

Disadvantage of condoms/ barrier methods

A

Canbe damaged and let

sperm in through
work better combined
with spermicide

82
Q

Kidney transplant advantages

A

kidneys work
cheaper
- people don’t need to go on
dialysis.

83
Q

Disadvatages of kidney transplant

A

-rejection
not enough available organs

84
Q

Disadvantages of dialysis

A

treatment is very time consuming 3-4 days
a week 3-4 hours a day
-expensive to run
- risk of blood clots
- risk of infection
Have to do it for life (unless get a transplant)

85
Q

Advantages of dialysis

A

Can function without a kidney/ can live

86
Q

Which hormones do the ovaries produce

A

Oestrogen- causes lining of uterus ti build up+ stimulates the release of lg and inhibits release of fsh

Progerterone- maintains lining of the itsrus during the second half of the cycle
I hibits the release of fsh and lh
When levels fall the lining of uterus breaks down

87
Q

Whoch hormones does the pituatry gland produce?

A

Fsh- cuasues gee yo mature, stimulates ovaries to produce oestrogen
Lh- stimulates the release if and egg at day 14

Adh-controls reabsortuon if water into hlood from kidneys

Biology (10 decks)

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