Homeostasis -Y10 Flashcards
(180 cards)
1
Q
What is homeostasis?
A
Maintaining a stable internal environment despite changing conditions
2
Q
Why does the body need to maintain optimal conditions?
A
For optimal enzyme action and cell function
3
Q
What is the role of a receptor?
A
Detects changes in the internal or external environment
4
Q
What is the role of a coordination centre?
A
Interprets changes and organises a response
5
Q
Name the two types of effectors and state what they do.
A
Muscles contract, whilst glands release hormones.
6
Q
Is the nervous system or the endocrine system faster acting?
A
Nervous
7
Q
Which system acts more generally across the body, the nervous system or the endocrine system?
A
Endocrine
8
Q
What is negative feedback?
A
When the levels of something get too high or too low, they’re brouht back down to normal
9
Q
CNS
A
Central Nervous System - consists of spinal cord and brain, connected to the body by sensory and motor neurones
10
Q
Sensory neurone
A
Carry electrical impulses to the CNS
11
Q
Motor Neurones
A
Carry electrical impulses from CNS to effector
12
Q
Effector
A
Muslces and glands repond to nervous impulses
13
Q
Synapse
A
Connection between 2 neurones
14
Q
Pathway of reflex arc
A
stimulus ➔ receptor ➔ sensory neurone ➔ relay neurone ➔ motor neurone ➔ effector ➔ response
15
Q
What is the role of a relay neurone?
A
To transfer a signal from a sensory neurone to a motor neurone
16
Q
Why are reflex important?
A
They protect us from harm and injury
17
Q
How do neurones work?
A
- Nerve signal is transferred by chemicals which diffuse across synapse.
- Chemicals set off a new electrical signal to next neurone
18
Q
What is a reflex action?
A
**Automatic and quick response **that doesn’t involve a conscious part in the brain
19
Q
3 reasons why treating the brain is difficult
A
- Complicated, so hard to target with medications
- Encased in skull, hard to access- fragile
- Huge range of consequences: mental illness, tumours, infections
20
Q
Ways to study the brain
A
- Electrical stimulation on diff parts to see how it affects persons behaviour
- MRI Scans - to see which part is most active during diff activities
- Studying patrients with brain damage and link that part of the brain to its function
21
Q
Cerebral cortex + describe it
A
- Consciousness
- Intelligence
- Memory
- Language
- Highly folded, takes up most of brain
22
Q
Cerebellum and where is it
A
Muscle coordination and balance
under (small) cerebral cortex
23
Q
Medulla + where
A
Unconscious activiies - breath and heart rate
small on brain stem top
24
Q
Hypothalamus
A
Responsible for regulating body temp
25
What hemisphere controls what?
Left hem - right side of body
Right hem - left side of body
26
Sclera
Tough, white supporting wall of the eye, protects eye
27
Cornea
* Light rays enter through **transparent** outer layer found at the front of the eye
* **Job: To start the focussing of the light rays**
28
Iris
Contains muscles that allow it to control the size of pupil
29
Pupil
Hole in the middle of iris - allows light rays to pass into eye
30
Lens
**Focuses light onto retina** (back of the eye)
* Can **change shape** so we can focus on distance/near objects - **accomodation**
31
Retina
Contains receptor cells sensitive to light intensity and colour
32
What controls the shape of the lens?
* Ciliary muscles
* Suspensory ligaments
33
Optic nerve
Carries electrical impulse from receptors on the retina to the brain
34
What happens to the eye in bright light?
Reflex triggered makes pupil smaller. Circular muslces in iris contract and radial muscles relax - reduces amount of light, protects from damage
35
What happens to the eye in dark light?
* Sensed by light receptors in retina and send electrical impulses to brain
* Brain send EI to specific muscles in iris
* Radial muscles contract and circular muscles relax, makes pupile wider and dilated
| reflex action
36
Process when eye looks at near objects
1. Ciliary muscles contract, slackens/loosen the suspensory ligaments
2. Lens becomes fat (more curved)
3. Increases amount by which it refracts light
37
What is accomodation?
When the eye focuses light on the retina by chaging the shape of the lens
38
2 types of receptor cells and what they do in the retina
* Cone cells = sensitive to colour of light - doesn't work well in low light
* Rod cells = more sensitive to light, only lets us see in black and white
39
Fovea
Place in retina which is full of only cone cells
40
What 2 muscles are the iris made out of?
* Circular muscles - inner
* radial muscles - outer
41
What is long-sightedness?
Hyperopia - when you can't focus on near objects
42
How is the eye in long-sighted people?
* Lens are the wrong shape
* Lens don't refract enough light
* Eyeball could be too short
* Images of near objects are brought into focus **behind** the retina
* elderly = lens becomes less elastic, cant become thick enough for near
43
How to treat hyperopia?
Glasses with a convex lens - lens refract light rays so they can focus on the retina
44
What is short-sightedness?
Myopia - when you can't focus on distant things
45
How is the eye in short-sighted people?
* Lens is wrong shape
* Lens refract too much light
* Eyeball is too long
* Images of distant objects are brought into focus in **front the retina**
46
How to treat myopia?
Glasses with a concave lens - so light rays focus on the retina
47
3 Alternatives of glasses
* Contact lenses
* Replacement lens surgery
* Laser eye surgery
48
What is the eye?
Sense organ containing receptors sensitive to light intensity and colour
49
Thermoregulation
Control of body temp (37')
50
What is the thermoregulatory centre?
Located in the hypothalamus, contains receptors that are sensitive to temp, receives impulses from receptors in skin
51
Mechanism for when you are hot
1. Sweat produced by sweat glands which evaporates - transfers energy to environment from body
2. Blood vessels dilate - more blood flows close to surface of skin (vasodilation) - helps transfer energy from skin to environment because more blood flows through capillaries - heat transfers out of blood
52
Mechanism for when you are cold
1. Hair stand up to trap an insulating layer of air
2. No sweat produced
3. Blood vessels constrict to close off skins blood supply - vasoconstriction
4. Shivering - skeletal muscles contract, to generate energy to shiver, muscles cells increase rate of respir. = releases heat + warms body
53
What are hormones?
* Chemical messengers/molecules
* Released directly into blood
* Only affect particular cells in particular organs (target organs)
* Produced by glands
* Long-lasting
54
Pituitary glands
* Produces many hormones and regulate body conditions
* 'master gland' - hormones act on other glands
55
Thyroid
* Produces thyroxine - regulates/increases rate of metabolism, heart rate and temp
56
Adrenal gland and where is it
* Produces adrenaline - fight or flight response
* top of kidneys
57
Pancreas
* Produces insulin - regulates blood sugar levels
58
Ovaries
* Produces oestrogen - menstrual cycle
59
Testes
* Produces testosterone - puberty and sperm production
60
Difference between nerves and hormones
Nerves:
* Fast
* Acts on precise area
* Short time
* Travels via blood
* Uses electrical impulses which travel down neurones
Hormones:
* Slower
* More general
* Lasts a long time
* Uses hormones which are chemicals carried in bloodsrteam
61
What happens when blood glucose levels are too low?
1. Pacreas detects low blood glucose level
2. Causes pancreas to release hormone glucagon into blood stream
3. Glucagon travels around body, binds mainly to cells in liver
4. stimulates those liver cells to break down their stored glycogen into glucose and release it into the blood.
5. Extra glucose increases levels to normal
62
What are the two main organs that insulin stimulates to absorb glucose from the blood?
Muscles and liver
63
What increases and decreases BGL?
Glucagon increases
Insulin decreases
64
Organ that detects changes in BGC
Pacreas
65
What happens if blood glucose concentrations fall too low?
There won't be enough glucose for tissue cells to respire
66
What happens to excess glucose?
Stored as glycogen (hormone) in liver and muscles
67
What happens when blood glucose levels are too high?
1. Pancreas detects level is too high releases insulin in bloodstream
2. Insulin bind to receptors on certain cells (mostly liver and muscle cells to form glycogen) that causes them to take some glucose thats in the blood
3. Levels decrease to normal
68
Type 1 diabetes
* Pacreas produces little/no insulin
* Need injections of insulin
* Limit intake of simple carbs
* Regular excercise
69
Type 2 diabetes
* Obesity - risk factor
* Resistant to own insulin (body doesn't respond properly)
* Carb controlled diet and excercise
70
What do the kidneys do?
* Remove waste products
* Regulate the level of ions
* Regulate the amount of water in the blood
71
Filteration (kidneys)
Substances filtered out of blood as it passes through the kidneys
72
Selective reabsorption
Useful substances like glucose, someions and right amount of water are reabsorbed babck into blood
73
What substances are removed from the body in urine?
* Urea
* Ions
* Water
74
How is water lost?
* Lungs when we exhale
* Sweat from skin (+ ions, urea)
* Urine - kidneys
75
What happens to excess amino acids?
* Liver breaks down excess amino acids
* Produces ammonia
* This process is deamination
* Ammonia is toxic so liver converts it into urea
* Excreted by kidneys
76
Waste product of deamination
Ammonia
77
What happens to ammonia?
It's toxic so it's converted to urea in the liver. Urea is transported to kidneys where it's filtered out of the blood and excreted by urine
78
What happens if there is a wrong amount of water in the body?
Upsets the balance between ions and water. Means too much or too little water is drawn into cells by osmosis. Can damage cells/ don't work normally
79
Ways ions are lost
* Sweat
* Urine
80
ADH
* Anti-diuretic hormone
* Released into bloodstream by pituitary gland
* Controls the concentration of urine
81
How does ADH work?
1. Brain (Hypothalamus) monitors the water content of the blood
2. Pituitary gland releases ADH according to how much is needed
3. Controlled by negative feedback
82
What does the tubule do?
Carries the filtered fluid that becomes urine
83
Blood enters the kidneys via the ----------- and leaves via the ------------.
1. renal arteries
2. renal veins
84
Which structure carries urine from the bladder out of the body?
Urethra
85
Consequences of kidney failure
* Waste substances build up in blood stream
* No regulation in water and ion levels
* Can cause death
86
Dialysis
Machine that filters blood.
87
In a dialysis machine, why is it important that the membrane between the blood and dialysis fluid is partially permeable?
To only allow some substances to diffuse across
88
In a dialysis machine, why is it important to continually pump fresh dialysis fluid through the machine?
To maintain a concentration gradient for diffusion across the membrane
89
Will fresh dialysis fluid contain urea?
No
90
Disadvantages of dialysis
* Risk of infection/blood clots
* Unpleasant experience
* Time consuming - 3 times a week, 3-4 hours
* Expensive to run in long term
* controlled diet
91
If a patient has a kidney transplant, what type of drugs are they required to take for the rest of their lives?
Immunosuppressants
92
Rejection of a transplanted organ process
1. Immune system treat's transplant as foreign so it tries to destroy it
2. Reduce risk by using meds
93
What is puberty?
Reproductive hormones causes secondary s characteristics to develop
94
What is stage 1 of the menstrual cycle?
The uterus lining breaks down for about 4 days
95
What is stage 2 of the menstrual cycle?
The uterus lining builds up again from day 4 to 14, into a thick spongy layer full of blood bessels, ready to receive a fertilised egg
96
What is stage 3 of the menstrual cycle?
An egg develops and is released (ovulation) at day 14
97
What is stage 4 of the menstrual cycle?
The wall is then maintained for about 14 days until 28 days. If there is no fertislised egg, cycle repeats and lining breaks down
98
FSH
| 3 p
Follicle- Stimulating hormone:
* Produced in pituitary gland
* Causes egg to mature in 1 one of the ovaries, in a follicle
* Stimulates ovaries to produce oestrogen
99
Oestrogen
| 3 p
* Produced in ovaries
* Causes lining of uterus to grow
* Stimulates release of LH and stops release of FSH
100
LH
| 2 p
Luteinising Hormone:
* Produced by pituitary gland
* Stimulates release of egg
101
Progesterone
| 4 p
* Produced in ovaries by remains of the follicle after ovulation
* When this level falls, lining breaks down
* Inhibits release of LH and FSH
102
How does oestrogen stop pregnancy?
* It prevents the release of an egg
* If its taken everyday to keep the level permanently high, it inhibits the production of FSH, & after a while egg development and production stop and stay stopped
103
How does progesterone prevent?
It stimulates the production of thick mucus which prevents any sperm getting and reaching the egg
104
What is the combined oral contraceptive pill?
Pill which has oestrogen and progesterone
105
Cons of the combined oral contraceptive pill
* Side effects e.g nausea
* Doesn't protect against STI
106
Contraceptive patch
* Oestrogen and progesterone
* 5cm X 5cm patch stuck onto skin
* Lasts 1 week
107
Contraceptive implant
* Inserted under skin of arm
* Releases continuous amount of prog.
(stops ovaries releasing eggs, makes it hard for sperm to swim)
* Lasts 3 yrs
108
Contraceptive injection
* Prog
* dose lasts 2 to 3 months
109
IUD
* Intrauterine device is a T-shaped device
* Inserted in uterus to kill sperm and prevent implantation of a fertilised egg
2 types:
Plastic IUD release prog
Copper IUD prevent sperm surviving in uterus
110
Diaphragm
Shallow plastic cup fits over cervix to form barrier
Has to be used with spermicide (disables/kills sperm)
111
Sterilisation
* Cutting or typing fallopian tubes
* Permanent procedure
* Very small chance tubes can rejoin
112
Natural methods
* Cycle is most fertile - avoid si
* Ineffective
113
Abstinence
Not to have it
114
What is the role of LH and FSH in IVF?
To stimulate serveral eggs to mature
115
Cons of using LH and FSH for fertility
* Doesn't always work - sometimes you have to repeat it - expensive
* Too many eggs could cause multiple births
116
What is IVF?
*In Vitro Fertilisaiton*
117
Process of IVF
1. Mother trated with FSH and LH - causes eggs to mature
2. eggs collected from mother
3. sperm from father is collected
4. Sperm is used to fertilise eggs in lab.
5. embryos formed
6. once its a tiny ball of cells, inserted into uterus
7. embryos develop
118
Cons of IVF
| 4 p
* Multiple births
* Success rate of IVF is low
* Emotionall/Physically stressful
* Strong reactions to hormones - vomiting, abdominal pain
* Not all embryos created will be transferred into the mother, so some destroyed unethical
* Expensive = could be used in cancer
119
What does adrenaline do?
| 4 p
* Increase heart rate
* Increase blood pressure
* Increase blood flow to muscles
* Increase blood sugar levels by stimulating liver to break glycogen down to glucose
120
TSH
*Thyroid stimulating hormone*
* Released from pituitary gland
121
Does thyroxine stimulate or inhibit the pituitary gland from releasing TSH?
Inhibit (stop)
122
What happens when thyroxine levels are too high?
1. Thyroxine will inhibit pituitary gland to produce TSH
2. TSH stimulates thyroid gland to produce thyroxine so less TSH would decrease thyoxine production
3. Thyroxine levels fall back normal over time due to negative feedback
123
What do auxins do?
Plant hormone that controls growth near the tips of shoots and roots
124
What way does auxin move and how?
1. auxin produced at tip of shoot
2. in shoots, auxin triggers cell growth
3. light causes auxin to concentrate on darker side of the shoot tip
4. Auxin spreads down the shoot
5. Cells on darker side grow faster than cells on light side
6. causes shoot to grow towards the light
125
Does auxin inhibit or stimulate growth in the shoots and roots?
Shoots = stimulate
Roots = inhibit
126
Phototropism
response to light
127
Geotropism/ gravitropism
response to gravity
128
Where are auxins accumulated?
Lower, shaded side
129
What does positively phototropic and negatively geotropic mean for shoots?
They grow towards the light and away from the gravity
130
3 hormones in plants
* Auxins
* Ethene
* Gibberellin
131
Auxins stimulate cells to grow and divide, so how can they be used as weedkillers?
If large amount of auxins are added to plants, it can disrupt their growth process by overstimulating them. This can kill the plant.
132
Dormancy
Seeds are inactive and do not grow/develop
133
Germination
Seeds begin to develop/grow
134
Which plant hormone can stimulate a plant to geminate?
Gibberellin
135
Explain how ethene is used in the transport of food.
* Ethene stimulates food to ripen
* Fruit is picked unripe so its still hard
* Means it isnt damaged during transport
* Ethene is used to ripen these fruit so it's soft for conusmers
136
What if there is too little water for cells?
Lose water and shrink
137
What detects the water conc in the blood stream?
Hypothalamus
138
What happens when the water levels are too low?
1. Hypothalamus detects the low conc of water in bloodstream
2. Send signal to pituitary gland to release ADH
3. ADH reaches kidneys and causes tubules to reabsorb more water into the blood
4. Water in blood increases
5. Causes less urine to be produced
139
What happens when water conc gets too high?
1. Detected by hypothalamus
2. Causes pituitary gland to stop sending ADH
3. Less ADH travels to kidneys so tubules reabsorb water into blood
4. More water will stay in the tubules so kidneys will produce more urine to get rid of extra water
140
Explain how the pituitary gland and kidney reduce water loss
1. low water conc/ low water potential of blood causes ADH release
2. ADH causes increased permeability of kidney tubules to water
3. so increased water reabsorbtion (more water taken into blood)
141
Advantages of kidney transplant
* Flexible lifestyle
* No risk of infection from frequent needles
* No need to control diet
* Cheaper long-term for NHS/hospital
142
Cons of kidney transplant
* Doesnt last forever
* Risks from surgery
* Recovery from surgery will take a long time
* Have to keep taking immunosurpressents so its not rejected by body
143
Biological reasons why kidney transplants are better than dialysis
* Not repeatdely puncturing skin - less chance of infection
* Changes in conc levels of substances/ urea minimised so less chance damage to body cells
144
Is urea toxic?
Yes
145
Stages of the reflex arc
1. Stimulus detected by receptor
2. Electrical impulses from receptor along a sensory neurone to the CNS
3. At the end of sensory neuron, there is a synapse
4. Chemical released at synapse
5. Chemical diffuses across to relay neurone in CNS where it triggers an electrical impulse
6. Electrical impulse passes across relay neurone and reaches another synapse
7. Chemical released
8. Trigger an electrical impulse in a motor neurone
9. Electric impulse down the motor neurone to effector
10. Muscle contracts = response
146
Ciliary muscles and suspensory ligaments
* Work with the lens
* allow us to focus on near/far
147
What happens to the eye when focussing on distant objects?
* light from distant needs to be focused only a small amount
* ciliary muscles relaxes and suspensory ligaments are pulled tight
* lens = pulled thin, so light rays slighly refracted
148
What does the thermoregulatory centre contain?
receptors which are sensitive to the temp of blood
149
What do the receptors in the skin do?
send electrical impulses down sensory neurones to thermoreg. centre
150
How do the kidneys remove urea and adjust levels of water and ions
1. Blood enters kidney through an artery (blood has urea)
2. Kidney removes this urea as well as excess ions and water
3. These leave the kidney as urine stored in bladder
4. Blood leaves kideny through vein (has no urea now)
5. Blood passes through capillaries where small molecules are filtered out of blood (urea, ions, water, glucose)
6. These pass into a tube, all glucose, some ions and water is reabsorped into blood (selective reabsorption)
7. urea, excess ions and excess water = urine
151
What happens when the blood becomes too concentrated/ level of water in blood falls?
1. Pituitary gland releases ADH into bloodstream
2. ADH travels to kidneys = causes kidney tubules to become mroe permeable to water
3. Means more water is reabsorped from the tubules back into the blood
4. This causes less urine to be produced and amount of water in blood returns to normal level
5. As level returns to normal, pituitary gland stops releasing ADH
| negative feedback cycle
152
What happens if the blood becomes too dilute when smn drinks a lot of water
1. Pituitary gland stops releasing ADH
2. So kidneys absorb less water into blood
3. More urine produced + conc of blood returns back to normal
153
Advantages of dialysis
no shortage of dialysis machines
154
Disadvantages of kidney transplants
* shortage of kidney donors
* Patients need to take anti-rejection drugs for rest of life
155
Pros of kidney transplant
* only expensive initially
* allow patrient = normal life
156
Ethene use
controls cell division and the ripening of fruits
157
Giberellin use
important in starting germination of seeds
158
2 ways to treat infertility?
* FSH and LH given to woman "fertility drug" causes more ovulation, increases chances of becoming pregnant
* IVF
159
# RP 8
Method of effect of light intenisty affecting height
1. Place cotton wool in 3 petri dishes and soak them with equal volume of water
2. volume of water = cotrol
3. plce 10 same mustard seeds in each dish
4. Leave dishes in warm place and allow them to germinate
5. water seeds everday with same vol of water
6. after a few days, make sure each petri dish has same no of seedlings (control v)
7. Use ruler to measure height of each seedling - hold stem straight, dont damage
8. place 3 dishes in diff conditions
9. 1 dish = full sunlight, 1 dish = partial light, 3rd = darkness
10. measure height of each seedlng for 5 days in table
11. calc mean seedling height for each day
12. draw diagrams to see effect of diff light intensity
160
what is auxin involved in
phototropism and gravitropism
161
horticulture
growing plants for gardens
162
Uses of auxin
* weedkillers
* rooting powders
* promoting growth in tissue culture
163
# RP 7
Reaction time method
1. 2 people
2. Person 1sits on a stool with good upright posture
3. Person 1 places forearm of dom arm across table overhanging table
4. person 2 hold ruler vertically
5. 0cm must be between person 1s thumb and first finger
6. person 2 tells person 1 to prepare to catch
7. person 2 drops ruler at random time
8. person 1 catches asap
9. person 2 records measurement above thumb
10. repeated and mean
11. switch places
12. iv = person dv = reaction time control = starting distance between first finger and thumb, top of thumb, lighting, background noise
163
Uses of giberellin
* used to end seed dormancy - force seed to germinate earlier
* encourage plants to flower
* fruit grow larger
164
What does laser eye surgery do?
change shape of cornea so it refracts light to a greater or lesser extent
165
What does it mean in terms of water if the blood is too concentrated?
level of water is low
166
What does ADH do?
increases water in blood
less urine produced
167
Role of thyroxine
* important for growth and development
* metabolic rate - chem reactions faster
168
TSH role
increases thyroxine production in the thyroid gland
169
What do unequal distributions of auxin cause?
unequal growth rates in plants shoots and roots
170
What does the skin have? What does the part 2 do?
temp receptors which send nervous impulses to the thermoregulatory centre which has receptors sensitive to tem p of blood
171
How is the structure of the nervous system adapted to its funciton?
* Long axon insulated by a fatty myelin sheath = long to carry msgs up and down bodt
* Dendrites = receive incoming impulses from other neurones
172
Where is water cooled?
mouth/stomach then sent to the brain
173
How does the brain receive info about light?
* cells in retina sensitive to light
* impulse passes along sensory neuron
* along to the optic nerve --> brain
174
What lens would fix hyperopia?
convex - image behind retina becomes focussed on the retina
175
When we look at a near object, what does the ciliary muscles do to have?
contract = smaller diameter
176
In an experiment for geotropism, why does the pot with seedlings rotating slowly act as the control?
gravity acts evenly on all sides
177
Difference between a reflex and conscious pathway
reflext - coordination cnetre is relay neuron in spinal cord/unconscious parts of brain
conscious = coordination centre is in conscious part of brain
178
2 types of contact lenses andd explain
hard - rigid material, long lasting, must be kept sterile
soft = flexbile, lasts for a shorter time, more comfortable
179
How can replacement lenses be used to treat visual defects
* can either be implanted into the eye
* or may replace natural lens altogether
* risks = infections, cataracts, retinal damage
