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Homeostasis Flashcards

1
Q

Define homeostasis

A

The maintence of keeping a constant stable internal environment for cells and to keep enzymes from being denatured

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2
Q

What condition are maintained by homeostasis?

A

Ph
Amount of water and glucose present in blood
temperature

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3
Q

What two effector systems are there?

A

Nervous and endocrine system

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4
Q

What are the three components of all control systems

A

Receptors - detect the change in environment
coordination systems - process the info from receptors and send out an effector
Effector- reverse the actual change in environment

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5
Q

what are the two main effectors and describe them

A

glands - usually the hormonal or digestive glands send out a slow response
Nerves - electrical impulses through the myelin sheath a fast instant response

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6
Q

what is the function of the nervous system?

A

allows body to react to stimulant and co ordinate a response

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7
Q

Describe from a stimulus to a response the role of the nervous system

A

stimulus is picked up by receptors and turned into an electrical impulse
this moves along sensory neruones to the CNS
The relay neruones in the CNS connect the sensory neruones to the motor neruones
the motor neruones carry the impulse to the effector which carry out the response

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8
Q

describe the sequence of events

A

stimulus - receptor - co -ordinator -effector - response

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9
Q

what is a reflex action?

A

an automatic and rapid response that doesn’t require the concious brain

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10
Q

describe how a reflex action occurs via a reflex arc

A

stimulus is detected by receptor
an electrical impulse is sent from the sensory neurones the the CNS
In the synapses between the sensory and relay nerurones a chemical diffuses and stimulates a new impulse across the relay neruones
same happens at the motor neurones
at the effector the appropiate impulse is carried for the response

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11
Q

difference between a reflex pathway and a conscious pathway?

A

within a reflex pathway the impulse is through a relay neruone in the spinal cord / unconious part of the brain
a concious pathway will use the conscious part of the brain

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12
Q

function of the cebreal cortex?

A

control’s concious, memory and languge

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13
Q

function of cerebellum?

A

muscle co-ordination

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14
Q

function of the medulla?

A

controls the unconcious activites of the brain e.g breathing heart rate

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15
Q

why is study and treatment of the brain so hard?

A

exact function of each part of brain is not known
brain is very delicate
brain can be easily damaged
certain membranes block drugs from reaching the brain

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16
Q

methods used to determine brain functions?

A

MRI scans
electrical impulsions
study of patients with brain damage

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17
Q

which stimuli are the eye receptors senstive too?

A

light intensity and colour

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18
Q

what are the two main functions of eye structures?

A

to adapt to dim conditions
focusing on near or far objects

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19
Q

describe the strucutre and function of the retina

A

Retina - light senstivie layer in the back of the eye
Light will stimulate the retina cells resulting in a impulse being sent to the brain (response from muscles being to shut eyes)

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20
Q

What are the 3 ways scientists study the brain?

A

MRI scans
electrically stimulating the brain
studying patients with brain damage

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21
Q

What are the main functions, eye structures are used for?

A

Accommodation (focusing on near and far objects)
Adapting to bright and dim light by opening and closing the lens

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22
Q

describe the function of the optic nerve

A

Connects the brain and eye
carries impulses,

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23
Q

describe the function of sclera?

A

tough white layer of the eye which protects the eye

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24
Q

describe the function of the cornea?

A

reflects light and allows it too enter and be focused onto the retina

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25
describe the function of the iris?
Is a muscle that controls the size of the pupil by contracting or relaxing
26
how does the iris alter the size of the pupil in dim and bright light?
bright light - circular muscles contract and radial muscles contract this makes the pupil smaller dim light the circular muscles relax and the radial muscles relax dilating the pupil
27
define accommodation
the alteration of the lens to focus on near and far objects
28
How does the eye focus on near objects?
Ciliary muscles contract suspensory ligaments slacken the lens becomes short and fat
29
how does the eye focus on far objects?
ciliary muscles loosen suspensory ligaments relax the lens become thinner light is refracted weakly
30
what is myopia?
short sightedness occurs when the lens of the eye is too curved so images will focus in front of the retina images are blurry
31
How can myopia be treated?
using concave glasses
32
what is hyperopia?
Long sightedness is when the lens is too flat so light will focus behind the retina
33
cure for hyperopia?
Using convex glasses lens which brings the light rays together
34
How does laser surgery work?
To treat myopia it is used to decrease the size of the cornea so light is refracted less strongly to treat hyperopia is treats the curavture of the lens
35
Pro's and con's of replacment lens?
Replacements lens will fix the lens can cause cataracts or blindess due to being so invasive
36
Where is the body is temperature controlled?
Thermoregulatory centre in the hypothalamus of the brain
37
Name the 4 hormones needed in the menstrual cycle?
LSH- lutenzing hormone FSH- follice stimulating hormone Oestrogen Proestrogen
38
What is the purpose of LH?
To stimulate the ovary to relase an egg every month, most highest concentrated when ovulation occurs
39
What is the purpose of FSH?
This stimulates the eggs in the ovaries to begin to mature and grow.
40
Purpose of proestrogen?
Maintains the uterine lining after ovulation.
41
Purpose of oestrogen?
stimulates the start of the uterus lining to build back up again, when it is low the uterus lining breaks down
42
Name the 3 neruones
Motor neurone, sensory neruone, receptor neurone
43
What are the two main structures found within the eye?
Focusing on near and far objects (accomodation) Adaptation to dim light
44
Describe the function and structure of the cornea?
It is a curved transparent part at the front of the eye that helps to bend and refract light onto the retina
45
Describe the function and structure of the iris?
Is a muscle that contracts and relaxes to control the size of the pupil, allows eyes to adjust to dim lighting
46
Describe how the iris alters the size of the pupil in both dim and bright light?
Bright light : the circular muscles contract and the radial muscles relax makes the pupil smaller so less light can enter eye Dim light: Circular muscles relax and radial muscles contract allowing more light into the eye
47
How does the eye focus on nearby objects?
cillary muscles contract suspensory ligaments loosen, so the lens becomes more curved so the light rays are refracted strongly
48
How does the eye focus on far objects?
cillary muscles loosen and suspensory ligaments loosen so the light rays are less refracted
49
What is myopia?
Myopia (short sightedness)occurs when the lens of the eye is too curved, so the light is focused in front of the retina so objects appear blurry
50
How can myopia be treated?
Can be treated with a concave lens which spreads out the light rays so they can be focused onto the retina
51
What is hyperopia?
Hyperopia (long sighted) usually occurs when the lens is too flat so light is focused behind the retina so objects appear out of focus
52
How can hyperopia be treated?
Hyperopia can be treated with a concave lens which brings the light rays closer together to be focused on the retina
53
What is laser eye surgery?
This fixes the size of the cornea, in myopia lasers reduce the size of the cornea so light is refracted less strongly In hyperopia the cornea curvature is changed so the light is refracted more strongly
54
Where is body temperature controlled?
Body temperature is controlled in the thermoregulatory centre in the brain.
55
How is temperature measured in the body?
The thermoregulatory centre has receptors in the blood that detect blood temperature The skin has receptors sensitive to skin temp
56
How does the body react when the temperature is too high?
Vasodilation- the blood vessels near the surface of the skin dilate, so more heat evaporates away Sweat - evaporation of water takes away heat energy from the surface of skin
57
How does the body react when the temperature is too low?
vasoconstriction- The blood vessels at the surface of the skin constrict so less heat evaporates Shivering - the work your muscles do create heat energy no sweating
58
What is the name of the body system that controls hormones?
The endocrine system
59
What is a hormone ?
Hormones is a chemical messenger released by glands, It travels to the target organ to create a response
60
What is the master gland?
The pituary gland
61
What is the role of pituary gland?
Secretes growth hormones - controls human growth Stimulates the the thyroid glans stimulates ovulation and oestrogen in the uterus
62
Role of thyroid gland
To secrete thyroxine which controls metabolism, heart rate and body temperature
63
What is the role of the pancreas?
To secrete insulin - controls glucose in blood
64
role of adrenal gland
to secrete adrenaline (ADH) to stimulate fight or flight response
65
How does the pancreas respond when glucose is low?
Pancreas releases glucagon which binds to the liver receptors making the stored glycogen break down into glucose again
65
how does the pancreas respond when the glucose levels are too high?
Pancreas secretes insulin which binds to the livers receptors, causing the excess glucose to be stored into the liver as glycgoen
66
How is blood glucose concentration controlled using a negative feedback loop?
When the blood glucose levels is below or above optimum the pancreas will secrete a hormone This action will do the opposite to the blood glucose level
67
what is type 1 diabetes?
An autoimmune disease when the pancreas fails to create enough insulin, so blood glucose levels are dangerously high
68
How can type 1 be treated?
Insulin injections inbetween meals so the glycogen can be broken into glucose pancreas and pancreatic cell transplants
69
what is type 2 diabetes
when the body stops responding to insulin- onset of obesity and age
70
how is water lost from body?
exhalation sweat urine
71
How are excess amino acids excreted from the body?
The excess amino acids are deaminated in the liver to form ammonia Ammonia is toxic so is converted into urea urea is excreted in urine and sweat
72
How do kidneys balance the amount of water, ions and glucose in the body?
The blood is filtered to remove waste(urea excess ions excess water) and the reabsorp useful molecules (glucose water and ions)
73
ADH?
Anti-diuretic hormone
74
How does ADH affect the reabsorption of water in the kidneys?
When the blood is too low in water more ADH is secreted ADH travels to the bloodstream of the kidneys, this increases the permeability of the kidney tubules so more water is reabsorbed into the blood
75
Why is kidney failure dangerous?
kidneys will be unable to filter the blood This will lead to a build of toxic urea an unbalanced amount of ions and water so osmosis in cells will not be correct
76
two ways of treating kidney failure?
Dialysis and transplant
77
what is kidney dialysis
Patient is hooked up to dialysis machine which contains fluids with the same concentration of glucose and ions as healthy blood. So therefore the patients blood will only lose urea and waste only
78
describe the events of the menstrual cycle
FSH is relased which makes eggs mature in the ovaries and promotes oestrogen which begins to thicken uterus lining Oestrogen promotes LH which makes ovulation occur and restricts anymore FSH Progesterone is secreted from the follicle of the ovary, which maintains the uterus lining and inhibits FSH and LH
79
How does contraceptive pill stop pregnancy?
Inhibts FSH so eggs do not mature and oestrogen to lining does not thicken and increases cervical mucus which slows down sperm cells
80
What is the IUS?
Is a small plastic device inserted into the uterus, so it relases progestogen and stops uterus lining thickening
81
what is the IUD?
Is a small copper device inserted into the uterus which prevents to implantation of embryos
82
How do fertility drugs increase the chance of pregnancy?
Contain FSH which promote egg maturtity which stimulate oestrogen production. They also contain LH which triggers ovulation
83
What is IVF?
Mother injects FSH and LH Eggs are collected from the ovary eggs are fertlised in a petri dish and developed into embryos the embryo's are then inserted into the mothers womb
84
Disadvantges of IVF?
Very expensive low success rate as you get older Increased chance of multiple pregnancy which is dangerous for mom
85
How is the relase of thyroxine controlled by negative feedback?
Thyroxine is a hormone relased by the thyroid gland.it is triggered by the thyroid stimulating hormone. Thyroxine stimulating hormone. when thyroxine is too low TSH is released
86
what are the effects of adrenaline?
Increased in heart and breathing rate- deilvers more oxygen and glucose to the body Stored glycogen converted into glucose dilation of pupils Blood diverted away from digestive system to muscle
87
What is a tropism?
A plants response to a stimulus
88
Phototropism?
Is a plant's shoots or roots response to light
89
gravatropism?
A plants response to gravity
90
Hydrotropism?
A plants response to water
91
what is auxin?
A hormone that controls the rate of growth and found in the tips of roots or shoots
92
How do plants show positive phototropsim?
One side of the plant is light causing the auxin to move to the dark side, at the dark side is stimulated to grow. bend towards the light this means more photosynthesis can occur
93
what are gibberelins?
A plant hormone that helps with seed germination
94
what is ethene?
a plant hormone involved in plant ripening
95
uses of auxin?
Weedkiller- auxins helps plants to grow at a rapid rate causing plant death Rooting powder- auxins causes a new plant to grow very quickly Tissue culture - promotes growth of roots and shoots from other plants quickly
96
uses of gibberelins?
Terminates seed dormancy Promotion of flowering Increases of fruit sizes
97

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