Chapter 5 - Homeostasis Flashcards
1
Q
What is homeostasis?
A
The regulation of the internal conditions in response to a change in the internal/external environment
2
Q
What are three types of homeostasis?
A
- Glucoregulation (glucose)
- Thermoregulation (temperature)
- Osmoregulation (water)
3
Q
Homeostasis is done by using automatic control systems. What are the features of these systems?
A
- Receptors
- Co-ordination centre
- Effectors
4
Q
What do we call the response to a change to the internal conditions?
A
Negative feedback effect
5
Q
What makes up the central nervous system (CNS)?
A
- Brain
- Spinal cord
6
Q
Nerve cell = neurone
What are the three types of neurone and what do they do?
A
- Sensory neurone: carries electrical impulse from the receptor to the CNS
- Motor neurone: carries electrical impulse from the CNS to the effector
- Relay neurone: carries electrical impulse from the sensory neurone to the motor neurone (to make reaction fast and automatic)
7
Q
What is a synapse?
A
A synapse is the gap between two neurones. When an impulse reaches the synapse, a chemical called neurotransmitter is released. This chemical travels across the gap by diffusion and is picked up by receptors on the next neurone. The chemical then triggers the impulse to continue.
8
Q
Explain how a reflex arc works?
A
- Stimulus detected by receptors
2.Electrical impulse pass from the receptor along the sensory neurone to the CNS
3.At the end of the sensory neurone is a synapse, where a chemical is released and diffuse across to a relay neurone in the CNS, where it triggers an electrical impulse
4.The impulse travels along the relay neurone to a synapse where the same happens to get to a motor neurone
5.The impulse travels along the motor neurone to the effector where a response occurs
DOES NOT GO VIA THE BRAIN SO AUTOMATIC!
9
Q
What are the three main parts of the brain called and what are their functions?
A
- Cerebral cortex: language, intelligence, memory and consciousness
- Cerebellum: balance and muscle co-ordination
- Medulla: unconscious activities such as heart rate and breathing rate
10
Q
What are the ways we can investigate the brain?
A
- Look at brain damage and link to function
- Electrically stimulate different parts of the brain and see the effects
- MRI scanning (what part of the brain is most active during different activities)
11
Q
What is the cornea?
A
Clear window that allows light into the eye
- Refracts light onto the retina
- Also serves as protection
12
Q
What is the optic nerve?
A
A bundle of sensory neurones (from receptors to the brain)
13
Q
What is the iris?
A
The coloured part of your a eye
- It is a ring of muscle that controls the size of the pupil
- Protects the photoreceptors from recieving too much light
14
Q
What is the pupil?
A
The hole in the centre of the iris that allows light to enter the eye
15
Q
What is the lens?
A
- Biconvex shape and flexible
- Focuses light on the back of the eye (retina)
16
Q
What are the ciliary muscles?
A
A ring of muscles around the lens
-controls the thickness of the lens
17
Q
What are the suspensory ligaments?
A
- Attached to the ciliary muscle
- Supports the lens
18
Q
What is the sclera?
A
Jelly-like substance that surrounds the eye
19
Q
What is the retina?
A
Back of the eye
- Where the photoreceptors are located
- Where images are formed
20
Q
How do we see?
A
- Light reflected off an object
- Most of the light is refracted by cornea
- Light enters through the pupil
- Light is refracted by the lens onto the rod and cone cells (receptor cells) on the retina
- The receptor cells are connected to neurones which carry messages to the optic fibre/optic nerve
- Optic fibre/optic nerve takes message to brain where the impulses are interpreted to create the images we see.
21
Q
What would happen if the lens did not function properly?
A
Light would not be focused on the retina causing vision to be blurred (short-sighted or long-sighted)
22
Q
What would happen if the optic nerve did not function properly?
A
No impulse sent to the brain so no image interpreted = blindness
23
Q
What would happen if the iris did not function properly?
A
- Too much light would enter eye causing damage to the retina
- Not enough light would enter meaning everything would look dark
24
Q
What would happen if the cone cells did not function properly?
A
Colour vision would be impaired
25
What is the iris/pupil reflex?
Very bright light can damage the retina so when light receptors detect very bright light a reflex is triggered that makes the circular muscles in the iris contract which makes the pupil smaller.
If there is very little light the radial muscles in the iris contract to make the pupil larger.
26
How does the eye focus?
The eye focuses light on the retina by changing the shape of the lens. This is called accommodation.
27
How do we focus on far away object?
1. Ciliary muscles relax
2. Suspensory ligaments pulled tight
3. Lens is pulled thin
4. Light rays are refracted less strongly
28
How do we focus on object near by?
1. Ciliary muscles contract
2. Suspensory ligaments lossen
3. Lens is allowed to get thicker
4. Light rays are refracted more strongly
29
What is hyperopia?
LONG-SIGHTED
- difficulty focusing on objects near by
- light is refracted and focuses behind the retina
- corrective lens = convex
30
What is myopia?
SHORT-SIGHTED
- difficulty focusing on objects further away
- light is refracted in front of the retina
- corrective lens = concave
31
Pros and cons of contact lens
```
Pros:
-no operation
-can easily be changed
-lightweight
-almost invisible
Cons:
-not permanent solution
-on-going cost
-can irritate eyes
```
32
Pros and cons of glasses
```
Pros;
-no operation
-can easily be changed
Cons:
-not permanent solution
-initial cost
-some people don't like them
```
33
Pros and cons of laser eye surgery
```
Pros:
-permanent
-no need for glasses or contacts
Cons:
-expensive procedure
-slight medical risk
```
34
How does the body detect changes in temperature?
- Thermoregulatory centre in the brain
| - Temperature receptors on the skin send impulses to the brain
35
What does the body do when it is too hot to cool down?
- hairs lay flat
- sweating
- vasodilation
36
What does the body do when it is too cold to warm up?
- hairs stand up
- shivering (respiration generates heat)
- vasoconstriction
37
What is the endocrine system?
The system that co-ordinates the body's organs so they work together. This is done by using chemical messengers called hormones, which are produced by glands.
38
What are the main glands of the endocrine system?
- Pituitary gland
- Thyroid gland
- Adrenal glands
- Pancreas
- Ovaries (female only)
- Testes (male only)
39
How does a hormonal response differ from a nervous response?
- Transported via bloodstream not neurones
- Slow acting apart from adrenaline
- Long lasting effects
- General effects or local effects not just specific targets
40
What organs are involved in blood glucose regulation?
- Pancreas
| - Liver
41
What does insulin do and where is it produced?
- Produced by pancreas
- Instructs liver to take glucose from the blood and convert it into glycogen
- This causes blood glucose levels to drop
42
What happens if your blood glucose levels are too low?
- Pancreas stops producing insulin and produces glucagon
| - This instructs liver to convert glycogen back into glucose
43
What is the difference between glycogen and glucagon?
```
Glucagon = hormone that triggers liver to convert glycogen into glucose
Glycogen = stored glucose
```
44
What is type 1 diabetes and how is it treated?
-Body doesn't produce enough insulin
-Usually developed early in life
Ways to treat:
-Insulin injects and manage diet/exercise
-Donor pancreas
-Stem cell therapy
45
What is type 2 diabetes and how is it treated?
-Person becomes resistant to their own insulin
-Being overweight and getting older increase your risk
Ways to treat:
-Carbohydrate-controlled diet
-Regular exercise
46
What happens to your cells if there is too much or too little water in your blood?
Too much in bloodstream: water diffuses into cells by osmosis causing them to swell and possibly burst
Too little: water leaves cells by osmosis causing them to shrink and shrivel
47
What organs are involved in water balance?
- Skin (sweating)
- Lungs (breathe out water vapour)
- Kidneys (control blood water level/filters water from blood)
- Brain (hypothalamus detects change in water level and pituitary releases ADH)
- Bladder (water let out in urine)
- Large intestine (absorption of water)
48
What does Anti-diuretic hormone (ADH) do?
When the hypothalamus detects too little water in the blood it triggers the pituitary to release ADH. This hormone instructs the kidney to maintain blood water level, therefore less water is lost in urine increasing the blood water level. If there is too much water less ADH is released so more water is filtered out in the urine by the kidney.
49
What is urine made up of?
- Urea
- Excess salt
- Excess water
50
What is haemodialysis?
Blood is filtered and cleaned in the dialysis machine. Arterial blood passes through a needle into a tube that goes into the dialysis machine, where waste is carried away. The clean blood then passes through a bubble trap and then returns to a vein.
51
What is peritoneal dialysis?
Dialysis fluid is run into your peritoneum through a catheter. Filtration then occurs inside the body before the dialysis fluid flows back out of the catheter carrying the waste products.
52
What are the downsides to dialysis?
```
Haemodialysis:
-Have to go back and forth from hospital
-Strict diet
-Near impossible to travel
-Needle phobia
Peritoneal dialysis:
-Major infection risk
-has to be done daily
-Might not work long-term
-Fluid can leak
```
53
What is transplantation?
If your kidney completely fails you will need a transplantation. This is where an organ is removed from a recently deceased or living (if non-essential organ) donor. This organ is then inserted and connected to the patient.
54
What are the risks of transplantation and how can you prevent them?
The main risk is rejection. The risk of this happening can be minimised by using a kidney with the same tissue type and blood type, and by using immunosuppressant drugs. However, immunosuppressants make it harder for the body to fight infections
55
What is the difference between excretion and elimination?
```
Excretion = removal of metabolic waste products from body
Elimination = removal of indigestible food
```
56
What is deamination and where does it happen?
Amino acid + oxygen = carbohydrate + ammonia
| This occurs in the liver
57
Ammonia is toxic! How does the body get rid of it?
In the liver, this chemical reaction occurs:
carbon dioxide + ammonia = urea + water
The products are taken from the liver to the kidney to be filtered and excreted.
58
What type of changes do we go through during puberty?
- Hormonal
- Physical
- Behavioural / mental changes
59
What hormones are part of the menstrual cycle?
- progesterone
- oestrogen
- LH (leutenising hormone)
- FSH (follicle stimulating hormone)
60
What does FSH do and how?
1. released from pituitary gland
2. transported in blood to ovaries
3. causes egg to mature
4. stimulates ovary to release oestrogen
61
What does oestrogen do and how?
1. released from ovaries
2. transported in blood to pituitary
3. stops release of FSH and stimulates pituitary to release LH
62
What does LH do and how?
1. released from pituitary
2. transported in blood to ovaries
3. causes ovary to release egg
4. stimulates ovary to release progesterone
63
What does progesterone do and how?
1. released from ovaries
| 2. maintain lining of uterus
64
What is contraception?
A device, drug, surgical procedure or sexual practice used for the intentional prevention of pregnancy
65
What are the 3 contraceptive types?
- Hormonal methods
- Non-hormonal / barrier methods
- Natural Planning
66
How does the contraceptive pill work?
Produces hormones that prevent pregnancy (oestrogen and progesterone)
- have to take regularly
- fertility returns quickly after stopping
- doesn't protect against STIs
- minor side effects
67
How does the male condom work?
Put over penis to stop sperm getting into the vagina
- protects against STIs
- one time use
- can slip off / split
68
How does the female condom work?
Worn inside vagina to stop semen getting into the womb
| -protects against STIs
69
How does the IUD work?
Inserted into uterus - blocks ovaries and releases hormones that prevent pregnancy
- long-lasting (3-10 years)
- can remove anytime
- fertility returns quickly
- doesn't protect against STIs
- small risk of infection
70
How does the diaphragm and cap work?
Fit inside vagina and cover the cervix
| -reusable
71
How do spermicides work?
It is a cream/gel/foam
- easy to use
- needs to be used alongside another type of contraception
72
How does the implant work?
Implanted in upper arm filled with progesterone
- Last 3 years
- Irregular periods
73
How does the injection work?
Injected with hormone that prevent pregnancy
- lasts 3 years
- side effects e.g. irregular bleeding and headaches
74
How does the contraceptive patch work?
Stuck to upper arm - hormonal control
- easy to use
- doesn't protect against STIs
- have to replace every 3 weeks
75
How does natural planning work?
Plot the times of the month that the female is infertile
| -can only have sex at certain times
76
How does sterilisation work?
Vasectomy or hysterectomy
- no risk of pregnancy at all
- irreversible
- surgery risks
77
What structures make up a nephron?
- Glomerulus
- Proximal tubule
- Loop of Henle
- Distal tubule
- Collecting duct
78
What does the glomerulus do?
Ultrafiltration
79
What does the proximal tubule do?
Selective Reabsorption
80
What does the loop of Henle do?
Osmoregulation (salt gradient)
81
What does the distal tubule do?
Selective Reabsorption
82
What does the collecting duct do?
Osmoregulation (water retention)
83
What is IVF?
Fertilisation in the lab outside of the mother's body.
84
How does IVF work?
1. Mother is given fertility drug which contains FSH and LH
2. She then chooses to have the treatment
3. Collect eggs from ovaries
4. Eggs combined with sperm in lab = fertilisation
5. Successfully fertilised eggs become embryos and are implanted into uterus lining
6. Embryo develops into foetus
85
What are the pros and cons of IVF?
```
Pros:
-helps women get pregnant
-less surgery
Cons:
-expensive
-not 100% effective
-chance of multiple births - bring health risks
```
86
What is adrenaline?
It is the hormone released when you are nervous or scared. It increases heart rate, dilates pupils and changes blood glucose levels.
87
What is an underactive thyroid?
- not enough thyroxine produced
- decreased metabolic rate
- gain weight, tired
88
What is an overactive thyroid?
- too much thyroxine produced
- lose weight, more energy
- enlarged thyroid gland
89
What are the three tropisms?
- Phototropism
- Geotropism
- Hydrotropism
90
What is phototropism?
Growth of plant in response to light
Positive = grows towards
Negative = grows away
91
What is geotropism?
Growth of plant in response to gravity
Positive = grows down/towards
Negative = grows up/away
92
What is hydrotropism?
Growth of plant in response to water/moisture
Positive = grows towards
Negative = grows away
93
What is auxin?
A plant hormone that controls growth in the shoots and roots
| More auxin promotes growth in shoots but inhibits growth in the root
94
How does auxin cause shoots to grow towards light?
Auxin diffuse to and accumulate on the side of the shoot in the shade This makes cells elongate faster on the shaded side and the shoot bends towards the light
95
How does auxin cause roots to grow towards gravity?
As the root grows sideways there will be more auxin on the lower side In roots auxin prevents growth meaning the cells on top will elongate faster and bend downwards
96
What are the three plant hormones used for commercial uses?
- Auxin
- Gibberellin
- Ethene
97
What are the commercial uses of auxin?
- weedkillers - causes weed to grow too quickly and die
- rooting powder which is used to grow plants from cuttings
- promoting growth in tissue culture
98
What are the commercial uses of gibberellin?
- Controlling dormancy (hibernation) so you can control germination
- Inducing flowering
- Growing larger fruit
99
What are the commercial uses of ethene?
Speed up the ripening of fruit - fruit can be transported unripe then ripened right before selling
