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Homeostasis And Response Flashcards

1
Q

Homeostasis

A

The regulation of internal conditions of a organism in response to internal or external changes

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2
Q

Conditions that are regulated

A

Body temperature

Glucose

Water

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3
Q

Receptors

A

Cells that detect a change (stimuli) in the internal or external environment

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4
Q

Coordination centres

A

Areas that receive and process information from receptors

E.g. the brain, spinal cord

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5
Q

Effectors

A

Muscles or glands that bring out a response to the stimuli

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6
Q

Structure of the nervous system

A

Stimulus - receptor - CNS - effector - response

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7
Q

Reflex action

A

Unconcious, automatic response to a stimulus

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8
Q

Reflex action practical

A

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 they must catch it

The number level with the top of person A’s thumb is recorded in a suitable table

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9
Q

Adaptations of a nerve cell

A

They have an long axon so they can carry messages up and down the body over long distances

The axon is insulated by a fatty myelin sheath - increases the speed of the nerve impulses along the neuron

Dendrites receive incoming nerve impulses from other neurons

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10
Q

Sensory neurone

A

The nerve cell that transmits electrical impulses from receptors in the sense organs to the CNS

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11
Q

Relay neurone

A

The nerve cell that transmits electrical impulses from sensory neurones to motor neurones

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12
Q

Motor neurone

A

The nerve cell that carries electrical impulses from the CNS to effectors

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13
Q

Synapses

A

A gap between neurones -

An electrical impulse travels along the first neurone

When it reaches the end of the neurone, neurotransmitters are released

The neurotransmitters diffuse across the synapse and bind with receptor molecules of the second neurone

This stimulates the second neurone to transmit the electrical impulse

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14
Q

Cerebral cortex

A

The outer layer of the brain

It is the centre of conscious thoughts and memories

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15
Q

Cerebellum

A

Controls balance, co-ordination of movement and muscular activity.

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16
Q

Medulla

A

Controls unconscious activities such as heart rate and breathing rate

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17
Q

MRI scans

A
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18
Q

EEG scan

A
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19
Q

Retina

A

Contains receptors which are sensitive to light

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20
Q

Optic nerve

A

Carries impulses from the retina to the brain

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21
Q

Sclera

A

A tough layer protecting the eye

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22
Q

Iris

A

Changes the size of the pupil to control the amount of light reaching the retina

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23
Q

Ciliary muscles + suspensory ligaments

A

Changes the shape of the lens

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24
Q

Focusing on a near object

A

The ciliary muscles contract

The suspensory ligaments loosen

The lens is then thicker and refracts light rays strongly

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25
Focusing on a distant object
The ciliary muscles relax The suspensory ligaments are pulled tight The lens is then pulled thin and only slightly refracts light rays
26
Myopia (short-sightedness)
The image is formed in front of the retina The eyeball is elongated Use a concave lens to fix
27
Hyperopia (long-sightedness)
Image is formed behind the retina The eyeball is too short Use a convex lens to fix
28
Thermoregulatory centre
Contains receptors sensitive to the temperature of the blood
29
Vasodilation
Blood vessels dilate and sweat is produced from the sweat glands
30
Vasoconstrict
Blood vessels constrict, sweating stops and skeletal muscles contract
31
Water loss
Water is lost through sweat, the lungs through exhalation, and through the kidneys via urine
32
Digestion of proteins
Excess amino acids need to be excreted safely Amino acids are deaminated to form ammonia in the liver Ammonia is toxic so it is immediately converted to urea for safe excretion in the kidneys
33
Kidneys
Removes excess water, salts and urea
34
The urinary system
Blood enters the kidney via the renal artery The blood is filtered at a high pressure, removing waste and the kidney selectively reabsorbs any useful materials such as glucose, salt ions and water Purified blood leaves through the renal vein The kidney produces urine, helping to maintain water balance
35
ADH (anti-diuretic hormone)
Released in the pituitary gland Controls water level in the body When the blood is too concentrated, kidney tubules become more permeable This allows more water to be reabsorbed back into the blood during selective reabsorption
36
Dialysis
When blood is removed from the body and filtered
37
Dialysis fluid
A glucose and ion concentration similar to a normal level in the blood No urea
38
Process of dialysis
Unfiltered blood that is high in urea is taken from a blood vessel in the arm Mixed with blood thinners to prevent clotting, and pumped into the dialysis machine Blood and dialysis fluid are separated by a partially permeable membrane
39
Advantages of dialysis
Reduces levels of urea Would not get rejected by body
40
Disadvantages of dialysis
Requires highly specialised and expensive machinery Patient must be connected to the machine for a long period of time Must monitor diet
41
Kidney transplant
Implanting a kidney from an organ donor into the patient’s body to replace the damaged kidney
42
Advantages of a kidney transplant
Cheaper for the NHS overall Patients can lead a more normal life without having to watch what they eat and drink
43
Disadvantages of a kidney transplant
Must take immune-suppressant drugs which increase the risk of infection Shortage of organ donors Kidney only lasts 8-9 years on average
44
Endocrine system
Made of glands that secrete chemicals called hormones into the blood stream The blood carries the hormone to the target organ where it produces an effect
45
Pituitary gland
The 'master gland' located at the base of the brain
46
Pancreas
Produces insulin - controls blood glucose levels
47
Type 1 diabetes (inherited)
Type 1 diabetes is a disorder in which the pancreas fails to produce enough insulin Treated with insulin injections
48
Type 2 diabetes (lifestyle)
Type 2 diabetes is when the person's body cells no longer respond to insulin produced by the pancreas Treated with a healthy diet and exercise
49
Symptoms of diabetes
Increased thirst and hunger Loss of weight, tiredness and nausea Vomiting and abdominal pain
50
Role of glucagon in control of blood sugar levels
If the blood glucose concentration is too low, the pancreas produces the hormone glucagon that causes glycogen to be converted into glucose and released into the blood If the blood glucose concentration is too high, the pancreas produces the hormone insulin that causes
51
Thyroid gland
Produces thyroxine - controls how much energy is used in your body
52
Adrenal gland
Produces adrenaline - prepares body for flight or fight
53
Ovary
Produces FSH, oestrogen, LH and progestogen
54
FSH hormone
Produced in the pituitary gland Causes an egg to mature in an ovary Stimulates the ovaries to release oestrogen
55
Oestrogen hormone
Produced in the ovaries Stops FSH being produced (so that only one egg matures in a cycle) Repairs, thickens and maintains the uterus lining Stimulates the pituitary gland to release LH
56
LH hormone
Produced in the pituitary gland Triggers ovulation (the release of a mature egg)
57
Progesterone hormone
Produced in the ovaries Maintains the lining of the uterus during the middle part of the menstrual cycle and during pregnancy
58
Oral contraceptives (hormonal)
Contains hormones to inhibit FSH production so that no eggs mature
59
Contraceptive injection, patch, implant (hormonal)
Where progesterone is slowly released to inhibit the maturation and release of eggs for a number of months or years
60
Barrier methods (non-hormonal)
Condoms and diaphragms which prevent the sperm reaching an egg
61
Intrauterine devices (non-hormonal)
Prevent the implantation of an embryo or release a hormone
62
Spermicidal agents (non-hormonal)
Kill or disable sperm
63
Abstinence (non-hormonal)
Abstaining from intercourse when an egg may be in the oviduct
64
Surgical methods
Male and female sterilisation
65
IVF
IVF involves giving a mother FSH and LH to stimulate the maturation of several eggs The eggs are collected from the mother and fertilised by sperm from the father in the laboratory The fertilised eggs develop into embryos At the stage when they are tiny balls of cells, one or two embryos are inserted into the mother's uterus (womb)
66
Fertility drug
A drug containing FSH and LH to help stimulate the maturity and release of the egg, equalling a higher chance of pregnancy
67
Phototropism
A response to the stimulus of light
68
Geotropism
A response to the stimulus of gravity
69
Positive tropisms
The plant grows towards the stimulus
70
Negative tropisms
The plant grows away from the stimulus
71
Auxins
Control the growth of plants by promoting cell division and causing elongation in plant cells Made in the tips of the growing stems and roots
72
Effect of light or gravity on the growth of newly germinated seedlings practical
Put cotton wool into three petri dishes, and add the same volume of water to each dish Add ten seeds to each dish and place them in a warm place where they won’t be disturbed Allow the seeds to germinate, and add more water if the cotton wool dries out Once the seeds have germinated, ensure the petri dishes each contain the same number of seeds, and remove any extra seeds if necessary One petri dish will sit in full light on a windowsill, the second will be in a dark cupboard, and the final dish will be placed in partial light Every day for one week, measure the height of each seedling and record the results in a table
73
Auxins
Weed killers Rooting powders Promoting growth in tissue culture
74
Ethene
Used in the food industry to control ripening of fruit during storage and transport
75
Gibberellins
End seed dormancy Promote flowering Increase fruit size

Biology (7 decks)

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