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Homeostasis 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
What does the hypothalamus do?
The hypothalamus regulates the bodies temperature as well as sending signals to the pituitary gland
26
What does the pituitary gland do?
The pituitary gland produces and secretes hormones e.g sex hormones, growth hormones, ADH
27
what do the ciliary muscles do ?
Involved in changing the shape of the lens
28
what does the iris do?
regulates the amount of light entering the pupil
29
What does the Cornea do?
Refracts light rays into the eye(as well as protecting the eyes surafce
30
what does the pupil do ?
a hole allowing light to enter the eye
31
ewhat does the lens do?
Focuses light on to the retina
32
What is the scelera( in terms of eyes)?
A though supporting wall of the eye
33
what doeds the optic nerve do ?
carries impulses from the receptors of the retina to the brain
34
What does the retina do ?
contains light receptors that sense light
35
What is the fovea?
area of the retina that provides the clearest vision
36
How do eyes focus on near objects?
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
What happens to the lens when focusing on distant object?
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
Describe and explain how the image is formed on the retina?
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
What are the two types of receptor cells in the retina and what do they do ?
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
The iris are made from two muscles what are they and what do they do
Radial muscles -They stretch from inside to outside like a radius. Circular muscles . circular muscles that stretch round the pupil like circles
41
How does iris reflex work(include radial and circular muscles in your explanation)?
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
what is hyperopia?
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
What are contact lenses?
Thin lenses that you put on surface of eye to improve eyesight by compensating for fault focusing
44
Pros of contact lenses
More convenient than glasses Unnoticeable(relatively invisible) Able to see better Fairly cheap
45
Cons of contact lenses
Higher risk of infection May be uncomfortable especially if a hard lens
46
What is laser eye surgery?
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
Pros of laser eye treatment
Better eyesight Don’t need to wear glasses
48
Cons of laser eye treatment
Expensive Risk of complications Higher risks of infections
49
What is replacement eye surgery
The lens from the eye is replaced with an artificial a lens
50
Pros of replacement lens surgery
Eye sight is improved Don’t need to buy or wear glasses or contacts
51
Cons of replacement lens surgery
Higher risk of damage to eye than laser eye surgery Risk of losing sight Risk of infections Risk of damaging retina
52
what do hormones control?
growth sexual development sugar level mood metabolism Side note: they stabilise the bodies internal environment
53
similarities between the ns and es
both monitor stimul98i and rect so as to maintain homeostasis
54
differences between the ns and es
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
What are hormones?
A chemical messenger that travels in the blood to activate target cells
56
What do sex hormones do in boys?
Puberty become muscular - Grow facial + pubic hair -voice breaks + becomes deeper - testes produce sperm + genitals develop
57
What doe sex hormones do in girls?
Puberty Breast develop Hips become wider Pubic hair Periods start
58
What does the ovaries do as an endocrine gland?
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
What does the thyroid produce and do (endocrine gland/es)?
Thyroid -produces hormone called thyroxine ↳ regulates rate of metabolism (main one) - Heart rate - deficiency causes overweight or sluggishness -excess can cause hyperactivity.
60
What does the adrenal glands produce and do?
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
What do the testes do and produce?
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
What does the pancreas do and produce? In terms of endocrine system
Pancreas produce hormone insulin ↳ insulin controls blood glucose conc Deficiency causes the condition’sugar diabetes' where the blood sugar is unregulated.
63
What does the pituitary gland produce and do?
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
What is glucose?
Glucose-a sugar used in respiration to make energy
65
What is glycogen?
Glycogen-a storage(storage form of glucose)substance made of glucose, it is stored in the liver and muscles(muscle cells)
66
What is insulin?
Insulin-a hormone that tells your body to change glucose into glycogen. It is made by the pancreas.
67
What is glucagon?
Glucagon-a hormone that tells the liver to change glycogen back into glucose. also made by the pancreas
68
What is type 1 diabetes?
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
What is ty
70
What is type 2 diabetes?
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
Why does insulin need to be injected rather than digested?
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
What is negative feedback?
Negative feedback-bodies response (corrective system) which restores a level back to its optimum in a system
73
Function of testosterone
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
What is tropism?
Tropism-a plants response to its environment
75
What does the body do to become cold when it’s too hot
Thermoregulation centre coordinates response sweat-evaporates-takes thermal energy with it -vasodilation (blood flows close to surface of the skin, - Hairs sie stat
76
What is normals body temp?
37 degrees celcius
77
What does the body do when it’s too cold and needs to warm
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
Danger of body temp too high
Enzymes denature
79
Danger of body temp too low
Reactions are slower
80
Advantages of barrier methods
no side as sects offee some protection
81
Disadvantage of condoms/ barrier methods
Canbe damaged and let sperm in through work better combined with spermicide
82
Kidney transplant advantages
kidneys work cheaper - people don't need to go on dialysis.
83
Disadvatages of kidney transplant
-rejection not enough available organs
84
Disadvantages of dialysis
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
Advantages of dialysis
Can function without a kidney/ can live
86
Which hormones do the ovaries produce
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
Whoch hormones does the pituatry gland produce?
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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