(Done) Homeostasis and response (Paper 2) Flashcards
(75 cards)
1
Q
Define homeostasis
A
- Regulation of internal conditions to maintain a stable environment in response to changes in internal and external conditions
2
Q
Function of receptors in a negative feedback loop
A
- Detects a stimulus - level is too high or low
3
Q
Function of a coordination centre in a negative feedback loop
A
- Receives and processes the information and organises a response
4
Q
Effector function in a negative feedback loop
A
- Produces a response, which counteracts the change and restores optimum levels
5
Q
List the parts of the nervous system
A
- Central nervous system (CNS)
- Sensory Neurones
- Motor Neurones
- Effectors
6
Q
What makes up the central nervous system
A
- Brain
- Spinal cord
7
Q
How is the central nervous system connected to the rest of the body
A
- Via motor neurones and sensory neurones
8
Q
Function of sensory neurones
A
- Carrying electrical impulses from the receptors to the CNS
9
Q
Function of motor neurones
A
- Carrying electrical impulses from the CNS to the effectors
10
Q
Define effectors
A
- All your muscles and glands which respond to nervous impulses
11
Q
Define receptors
A
- Cells that detect stimuli
12
Q
How do different types of effectors react to stimuli
A
- Muscles contract in response to stimuli
- Glands secrete hormones in response to stimuli
13
Q
Define synapse
A
- The connection between two neurones
14
Q
How do synapses transfer the signals across neurones
A
- Transferred by chemicals which diffuse across the gap between neurones
- These chemicals then set off a new electrical signal in the next neurone
15
Q
Define reflexes
A
- Rapid, automatic responses to certain stimuli that don’t involve the conscious part of the brain
16
Q
Define reflex arc
A
- The passage of information in a reflex from receptor to effector
17
Q
Where do the neurones in a reflex arc go through
A
- The spinal cord
- The unconscious part of the brain
18
Q
Function of relay neurones
A
- To connect the sensory neurones to the motor neurones
19
Q
Why are reflexes faster than conscious responses
A
- They do not travel the entire length of the CNS and are automatic instead of manual
20
Q
List the three main parts of the brain
A
- Cerebral Cortex
- Medulla
- Cerebellum
21
Q
Features of the cerebral cortex
A
- The outer wrinkly bit
- Responsible for consciousness, intelligence, memory and language
22
Q
Features of the medula
A
- Controls unconscious activities such as breathing and heartbeats
23
Q
Features of the cerebellum
A
- Responsible for muscle coordination
24
Q
List the 3 methods to study the brain
A
- Studying patients with brain damage
- Electrically stimulation the brain
- MRI scans
25
Features of studying patients with brain damage
- Observing the part of the brain that has been damaged and the effect it has on the patient
26
Features of electrically stimulating the brain
- Observing what different parts of the brain do when electrically stimulated
27
Features of MRI scans
- Magnetic resonance imagery, produces detailed images of the brain, find out which parts of the brain are active when people are doing certain things
28
Risks of brain research
- Physical damage
- increased problems with brain function
29
What is the Sclera
- Tough, supporting wall of the eye
30
What is the Cornea
- Transparent outer layer at the front of the eye
- Refracts light into eye
31
What is the Iris
- Contains muscles that control the diameter of the pupil and how much light enters the eye
32
What is the lens
- Focuses light onto the retina
33
What is the Retina
- Contains receptor cells sensitive to light intensity and colour
34
What controls the shape of the lense
- Ciliary muscles and suspensory ligaments
35
What is the optic nerve
- Carries impulses from the receptors on the retina to the brain
36
What is the iris reflex
- When the light receptors in the eye detect bright or dim light so the diameter of the pupil changes
37
What happens when the eye detects too much light
- The ciliary muscles contract and the radial muscles relax
38
What happens when the eye detects too little light
- The ciliary muscles relax and the radial muscles contract
39
What is accomodation
- When the eye focuses light on the retina by changing the shape of the lense
40
What happens when you try and look at nearby objects
- Ciliary muscles contract which loosens the suspensory ligaments
- The lens becomes more curved
- Increases the amount by which it refracts light
41
What happens when you try to look at far away objects
- The ciliary muscles relax which slackens the suspensory ligaments
- This makes the lens less curved
- Decreases the amount by which it refracts light
42
Treatments for vision defects
- Contact lenses
- Laser eye surgery - Laser vaporizing tissue, changing the shape of the cornea
- Replacement lens surgery - Natural lens of the eye is removed in surgery and is replaced with an artificial lens correcting the sight defect
43
Process of regulating body temperature
- Temperature receptors - detect that the temperature of the body is irregular
- Thermoregulatory center - Receives information from the receptors and triggers the effect automatically
- Effectors - Muscles shiver or sweat glands open to counteract the irregularity
44
Body's reaction when body temperature is too high
- Sweat is produced and evaporates from the skin, transferring energy to the environment
- Blood vessels near the skin dilate so more blood flows to the surface of the skin, transferring more energy from the body to the environment
45
Body's reaction when temperature is too low
- Hairs stand up to trap an insulating layer of air near the skin
- Blood vessels near the skin contract to reduce the amount of energy transferred to the environment
- Muscle fibers contract automatically, which requires respiration which transfers some warm energy back to the body
46
List the glands and what hormones they produce
- Pituitary gland - many hormones that regulate body conditions as well as telling other glands to release their hormones
- Thyroid - Thyroxine
- Ovaries - Estrogen
- Adrenal gland - Adrenaline
- Pancreas - Insulin
- Testes - Testosterone
47
Effects of hormones
- Thyroxine - Rate of metabolism, heart rate, temperature
- Estrogen - Involved in the menstrual cycle
- Adrenaline - Prepare the body for a fight or flight response
- Testosterone - Controls puberty and sperm production
- Insulin - Regulates blood glucose level
48
Features of nerve responses
- Very fast action
- Acts for a short time
- Acts on a precise area
49
Features of hormone responses
- Slower action time
- Act for a long time
- Act in a more general way
50
Cause, effects and treatment of type 1 diabetes
- When the pancreas doesn't release enough insulin
- A persons glucose levels can rise to a level that can kill them
- Treated via several injections of insulin throughout the day
51
Cause and treatment of type 2 diabetes
- When someone becomes resistant to their own insulin (still produced however their cells don't respond correctly to the hormone)
- Eating a carbohydrate-controlled diet and getting regular exercise
52
What substances are removed from the body through the kidneys and urine
- Urea
- Ions
- Water
53
How is the concentration of urine controlled
- The brain monitors the water content of the blood and instructs the pituitary gland to release ADH into the blood according to how much is needed
- Less ADH means less water is reabsorbed from the kidney tubules
- More ADH means more water is reabsorbed from the kidney tubules
54
Describe the process of the negative feedback loop that controls the concentration of urine
- A receptor in the brain detects an abnormality in the water content of the blood
- The coordination centre in the brain receives the information and coordinates a response
- The pituitary gland changes the amount of ADH it releases to compensate for the abnormality in blood water content
55
Effects of kidney failure
- Waste substances build up in the blood and eventually you lose control over the levels of water and ions in your body, eventually resulting in death
56
Treatments for kidney failure
- Kidney dialysis treatment
- Kidney transplants
57
How does kidney dialysis work
- The persons blood flows between partially permeable membranes, surrounded by dialysis fluid
- The membrane is permeable to smaller particles like ions and waste substances but not proteins
- The dialysis fluid has the same concentration of dissolved ions and glucose as healthy blood
- This means that the useful amount of glucose and ions will not diffuse out of the blood
- Only waste products such as urea and excess ions and water will diffuse
58
Advantages and disadvantages of kidney dialysis
Advantages
- Can provide someone with kidney failure the time needed to find a donor
Disadvantages
- Has to occur 3 times a week
- Lasts for 3-4 hours
- Very expensive for the NHS
- May cause blood clots and infections
59
Issues with kidney donations
- Finding a donor is difficult
- Kidney may get rejected
60
Describe the four stages of the menstrual cycle
- Day 1 to 4 - Menstruation starts and the uterus lining breaks down lasting for about 4 days
- Day 4 to 14 - The uterus lining builds up again into a thick, spongy layer full of blood vessels, ready to receive a fertilised egg
- Day 14 - An egg develops and is released from the ovary also known as ovulation
- Day 14 to 28 - The wall is maintained, If no fertilised egg has landed on the uterus walls by day 28 the uterus lining breaks down and the cycle starts all over again
61
Features of FSH
- Produced in the pituitary gland
- Causes the egg to mature in one of the ovaries ovaries, in a structure called the follicle
- Stimulates the ovaries to produce oestrogen
62
Features of oestrogen
- Produced in the ovaries
- Causes the lining of the uterus to grow
- Stimulates the release of LH and inhibits release of FSH
63
Features of LH
- Produced by the pituitary gland
- stimulates ovulation
64
Features of progesterone
- Produced in the ovaries by the remains of the follicle after ovulation
- Maintains the uterus during the second half of the cycle, when the levels of progesterone drop, the lining of the uterus breaks down
- Inhibits the release of FSH and LH
65
How can hormones be used to reduce fertility
- Oestrogen can be used to prevent the release of an egg because if the levels of oestrogen are permanently high, FSH production is inhibited and production of the egg will stop
- Progesterone can be used to reduce fertility as it can stimulate the production of thick mucus which prevents any sperm from reaching the egg
66
List the types of ways fertility can be reduced
- Hormonal treatment
- Barriers
- Sterilisation
- Rhythm method
- Abstinence
67
How can hormones be used to increase fertility
- FSH and LH can be used to stimulate ovulation
68
Describe IVF
- When eggs are collected from the woman's ovaries and fertilised in a lab using the man's sperm
-The fertilised eggs are then grown into embryos in a laboratory incubator
- Once the embryo's are tiny balls of cells, one or two of them are transferred into the woman's uterus to increase the chance of pregnancy
69
Features of adrenaline
- Released in response to stressful or scary situations
- Your brain detects fear or stress and send nervous impulses to the adrenal glands which respond by releasing adrenaline
- Increases the supply of oxygen and glucose to cells in the brain or muscles
70
Features of thyroxine
- Plays an important role in regulating the basal metabolic rate
- Stimulates proteins synthesis for growth and development
- Released in response to thyroxine stimulating hormone from the pituitary gland
71
Define auxin
- A plant hormone that controls growth near the tips of roots and shoots
72
Features of auxins
- Produced at the tip and moves backwards to promote cell elongation
73
Commercial uses of auxins
- Weed killers
- Growing form cuttings with root powder
- Growing cells in tissue cultures
74
Features of gibberellin
- Control dormancy
- Induce flowering
- Growing larger fruit
75
Effects of ethene on plants
- Stimulates enzymes that cause the fruits to ripen
