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GCSE Biology > Homeostasis and Response > Flashcards

Homeostasis and Response Flashcards

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1
Q

What is Homeostasis?

A

the regulation of the conditions in the body to maintain a stable environment

  • responds to both internal and external
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2
Q

What are automatic control systems?

A

systems that regulate internal environment

  • body temperature, blood glucose level, water content
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3
Q

What are the 3 main components automatic control systems made up of?

A

Receptors
Coordination centres (brain, spinal cord, pancreas)
Effectors

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4
Q

What is negative feedback?

A

A system the automatic control systems use to bring levels (water, temp etc) back to normal

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5
Q

What are the different parts of the Nervous system?

A

CNS- Central Nervous System
- consists of brain and spinal cord only

Sensory Neurone
- carries information as electrical impulses from receptors to the CNS

Motor Neurone
- carries impulses form CNS to effectors

Effectors
- all muscles and glands, response to nervous impulses

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5
Q

What happens when the levels are too high?

A
  • Receptor detects a stimuli
  • Coordination centre receives + processes information, organises response
  • Effector produces response, counteracts the change, restores optimum level
  • level decreases
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5
Q

What happens when the levels are too low?

A
  • Receptor detects a stimuli
  • Coordination receives and processes information, organises response
  • Effector produces response, counteracts change, restores optimum level
  • Level increases
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5
Q

What is the Nervous system?

A

Detects and reacts to stimuli

  • humans react to their surroundings, coordinate behaviour
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5
Q

What are receptors?

A

Cells that detect stimuli

  • taste receptors, sound receptors (ears, tongue)
  • form parts of larger organs (retina= light receptor cell)
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6
Q

What are Effectors?

A

Respond to nervous impulses and brings back a change

  • muscles and glands
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6
Q

What can effectors and receptors form?

A

part of complex organs

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6
Q

How do Muscles respond as an effector?

A

they contract

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7
Q

How do Glands respond as an effector?

A

secrete hormones

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7
Q

What is the role of the CNS?

A

Coordination centre

  • coordinates a response
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7
Q

What is a synapse?

A

the connection between 2 neurones

  • nerve signal transferred by chemicals
  • diffuse across the gap
  • set off new electrical signal to the next neurone
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8
Q

What are Reflexes?

A

Rapid automatic responses to certain stimuli

  • don’t involve the conscious part of the brain
  • reduce chances of being injured
  • bright light-> pupils get smaller
    -shock-> body releases adrenaline
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9
Q

What is the a reflex arc?

A
  • the passage of information in a reflex (from receptor to effector)
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10
Q

What is the process of a reflex arc?

A

1- Stimuli (Bee stings finger)
2- Stimulus detected by pain receptor
3- Impulses sent along sensory neurone to relay neurone in the CNS (through spinal cord OR unconscious part of brain)
4- Impulses reach a synapse (between sensory and relay neurone), trigger chemical release, sends impulse to relay neurone
5- Impulses reach synapse between relay and motor neurone, chemicals released, sends impulse
6- impulses travel from motor neurone to effector (muscle or gland)
7- muscle contracts, move away from the bee (quicker than normal reaction, unconscious)

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11
Q

What is the brain?

A
  • Made up of billions of interconnected neurones
  • In charge of all complex behaviours
  • In charge of many different functions (different regions)
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12
Q

What are the different components of the brain?

A

Cerebral cortex
Medulla
Cerebellum
Spinal Cord
Pituitary Gland
Hypothalamus

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13
Q

What is the role of the Cerebral Cortex?

A

Consciousness, Intelligence, Memory, Language

  • Outer wrinkly layer
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14
Q

What is the role of the Medulla?

A

Controls unconscious activities
(breathing, heartbeat)

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15
Q

What is the role of the Cerebellum?

A

Responsible for muscle coordination

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16
Q

What is the role of the Hypothalamus?

A

Controls Homeostasis

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17
What is the role of the Spinal Cord?
Part of the reflex arc - motor commands
18
What is the role of the Pituitary Gland?
Produces hormones that regulate body conditions - master gland - hormones released act on glands, directing them to release hormones that bring about change
19
What methods do scientists use to study the brain?
MRI Scans Electrically Stimulating the Brain Studying patients with brain damage.
20
How do scientists study patients with brain damage?
The scientists can understand the effect that damage to a small part of the brain can have on a patient - Can see what part of the brain is damaged by looking at the effect the damage had on a person - brain damaged by stroke, patient has gone blind, part of brain damaged= to do with vision
21
How do scientists Electrically stimulate the brain to study it?
Pushing a small electrode into the tissue, giving it a small charge. Observing the effect of the stimulus, scientists can figure out what parts of the brain control what. - area is stimulated, causes muscle contraction, brain part controls motor
22
How can scientists use MRI scans to study the brain?
-Machine that produces a detailed image of brain structures - can see what areas of the brain are active when people do things (listen to music, try to recall a memory) - Magnetic resonance imaging
23
How can the investigation into the brain have consequences?
- difficult, complex - risks: physical damage to brain, increase problems with brain function (difficulty to speak)
24
How can the investigation into the brain be beneficial?
Led to the development for disorders - reduce muscle tremors caused by nervous system (Parkinsons)
25
What are the components of the eye?
Sclera: Tough, supporting wall of the eye Cornea: Transparent outer layer at front of the eye (refracts light into the eye) Iris: Muscles that allow control of diameter of the pupil, how much light enters the eye Pupil: Hole in the middle of the eye, changes diameter to let light into the eye Lens: Focuses light onto the retina Retina: Contains receptor cells sensitive to light intensity and colour Ciliary muscles: Controls shape of lens Suspensory ligaments: Controls shape of lens Optic nerve: Carried impulses from retina receptors to brain
26
What is the fovea?
Point in the Retina where light aims to focus - high number of receptors
27
How does the Iris adjust to bright light?
- Bright light can damage the iris - reflex is triggered - Circular muscles contract - Radial muscles relax - Makes pupil smaller, reduces amount of light going into eye
28
How does the Iris adjust to dim light?
- Dim light triggers a reflex - Circular muscles relax - Radial muscles contract - Makes pupils larger, increases amount of light going into the eye
29
What is accommodation?
The eye changes the shape of the lens to focus light on the retina
30
How does the eye change lens shape to focus on nearby objects?
- Ciliary muscles contract - Suspensory ligaments slacken - Lens becomes short and fat, increasing the angle of light refraction
31
How does the eye change lens shape to focus on far away objects?
- Ciliary muscles relax - Suspensory ligaments contract - Lens becomes long and thin, decreases the angle of light refraction
32
What is Hyperopia?
The condition which leaves people unable to focus on near objects (long-sighted) - lens is too short, fat, doesn't refract light enough - focuses image behind retina
33
What is Myopia?
The condition which leaves people unable to focus on distant objects -lens is too long, thin, refracts light too much - image is formed in front of the retina
33
How do you correct Hyperopia?
Glasses with a convex lens - refracts light to focus on the retina
34
How can you correct Myopia?
- Use glasses with a concave lens - light focuses on retina
35
What are other treatments for vision defects? (not glasses)
- Contact lenses - Laser eye surgery - Replacement lens surgery
36
What are Contact lenses?
Thin lenses that sit on top of the eye - lightweight, invisible - more convenient than glasses - Soft lenses, Hard lenses
37
What is Laser eye surgery?
Laser vaporises tissue, changing the shape of the cornea (the strength of refraction) Slim down cornea- myopia Strengthen cornea - hyperopia - risk of surgical complication
38
What is Replacement lens surgery?
Replacing the lens of the eye- Long-sighted - natural lens replaces with artificial lens - Higher risk than laser, possible damage of the retina (worse vision, blind)
39
What is the Body's temperature
37 degrees
40
What controls body temperature?
Thermoregulatory centre in brain - contains temperature sensitive receptors (of the blood) - skin (skin temperature)
41
How does the thermoregulatory centre react to a high body temperature?
- Temperature receptors detect core body temp is too high - Thermoregulatory centre acts as a coordination centre, receives information from temperature receptors, triggers effectors automatically - Effectors (sweat glands) produce response and counteract change
42
How does the thermoregulatory centre react to a low body temperature?
- Temperature receptors detect core body temp is too low - Thermoregulatory centre acts as coordination centre, receives info from temp receptors, triggers effectors - Effectors (muscles) produce a response and counteract change
43
How does the body react to counteract hot temperatures?
- Sweat glands produce sweat, transfers energy to environment, evapourates from skin - Blood vessels dilate, seem closer to the skin (vasodilation) - Hair erector muscles, lie close to skin, reduce air around the skin Transfers energy to the surrounding environment
44
How does the body react to counteract low temperatures?
- Hairs stand up to trap and insulating layer of air - No sweat is produced - Blood vessels supplying skin capillaries constrict, appear smaller (vasoconstriction) -Shivering, needs respiration, transfers energy to warm the body
45
What are Hormones?
Chemical molecules released directly in the blood - carried through all organs, only effect specific organs - produced by endocrine glands - long lasting effects
46
What are the main glands in the body?
The Pituitary Gland Thyroid Ovaries (females) Testes (males) Adrenal Gland The Pancreas
47
What is the role of the Pituitary gland ?
Produces many hormones that regulate body conditions - Master gland - produces hormones that act on other glands, bring change
48
What is the role of the Adrenal gland?
Produces adrenaline - prepares body for 'fight or flight' reaction
48
What is the role of the Testes (male)?
Controls puberty and produces sperm in males
48
What is the role of the Ovaries (female)?
Produces Oestrogen, involved in menstrual cycle
48
What is the role of the Thyroid?
Produces Thyroxine - regulates rate of metabolism, heart rate, temperature
48
What is the difference between Nerves and Hormones?
Nerves: - Fast acting - Short time - Precise area Hormones: - Slower acting - Long time - Act in general way
48
What is metabolism?
All chemical reactions in a cell of an organism
48
What are levels of glucose controlled by?
- Metabolism of cells (removes glucose) - Vigorous exercise (removes lot glucose) - Insulin and Glucagon
49
What is Insulin?
Hormone involved in the regulation of blood glucose (decreases levels) - stored in pancreas
50
What is the role of the Pancreas?
Organ that helps to maintain blood sugar levels also produces digestive enzymes
50
What is Glucagon?
Hormone involved in the regulation of blood glucose (increases levels) - initiates glycogen to be turned to glucose and released into blood
51
What is Type 1 Diabetes?
The pancreas produces little to no insulin - Insulin therapy (injections of insulin throughout the day, at mealtimes) - regular exercise - limiting intake of carbohydrates - develop during younger age ranges
51
What is Diabetes?
Condition that affects the ability control blood sugar levels
52
What is Type 2 Diabetes?
A person becomes resistant to their own insulin (body cells don't respond to the insulin) - overweight-> increases chances (risk factor) - carbohydrate controlled diet - regular exercise - develop at older age ranges
53
What happens if the blood glucose level is too high?
- Insulin secreted by the pancreas into blood -Blood taken to liver (with insulin), Glucose moves from blood into liver and muscle cells - Insulin makes liver turn glucose into glycogen - Blood glucose reduced
53
What happens if the blood glucose level is too low?
- Glucagon secreted by the pancreas -Blood with glucagon travels to liver, Glucagon makes liver turn glycogen into glucose. - Blood glucose is increased
54
What is Glycogen?
Store of glucose in the liver and the muscles
55
What are the Kidneys?
Make urine by taking waste products out of the blood. (filtration) Useful substances are reabsorbed by the blood (Selective reabsorption) - Organ important to Homeostasis
56
What substances are removed from the body into the urine? (by kidneys)
- Urea - Ions - Water
57
What is Urea?
Ammonia that is converted in the liver (nontoxic) - Proteins and amino acids cannot be stored in the body (excess are converted into fats and carbohydrates-> in liver, DEAMINATION - Ammonia is a waste product from this process, toxic, converted into urea, transported and filtered out in the kidneys
58
What are Ions?
ie Sodium (from food) -balance between ions and water in the body, sometimes too much water is drawn to cells by osmosis - some ions are lost in sweat, others maintained by kidneys, reabsorbed right amount into the blood, rest is filtered out in urine.
59
Why is Water a product in urine?
- Body constantly balances the intake and release of water - lose water from sweat and exhaling (uncontrolled) - balanced by consumption and amount removed by kidneys in urine
60
What is the concentration of urine controlled by?
ADH- anti diuretic hormone - increases water content reabsorbed
61
How is the concentration of urine controlled?
ADH released by pituitary gland into bloodstream Brain monitors water content and instructs pituitary gland in how much ADH to release and when (negative feedback)
62
What happens if the water content in the body is too high?
- A receptor in the brain detects water content is high - Coordination centre in brain receives information, coordinates response - Pituitary gland released less ADH so less water is reabsorbed from kidney tubules.
63
What happens if the water content in the body is too low?
- Receptor in brain detects water content is too low - Coordination centre in brain receives information, coordinates response - Pituitary gland releases more ADH, more water is reabsorbed by kidney tubules.
64
What are the 2 main treatments for Kidney Failure?
- Regular Dialysis - Transplant
65
What happens if your Kidney's fail?
Waste substances build up in the blood Lose ability to control levels of ions and water Results in death (if untreated)
66
What is a Dialysis machine?
A machine that filters blood through partially permeable membranes to diffuse useful substances into the blood, and take waste substances out (filtration)
67
What do Dialysis machines do?
- Blood flows between partially permeable membranes, surrounded by dialysis fluid (permeable for ions + waste, not protein) - Dialysis fluid has same concentration of ions and glucose and healthy blood (useful ions and glucose won't be lost from the blood during dialysis, only waste like urea and excess ions, water etc)
68
What are the pros and cons of Dialysis?
Cons - 3 to 4 times a week, 3-4 hours each session (time consuming) - Can cause blood clots, infections - uncomfortable - expensive for NHS Pros - Buys time for donor organ to be found - Can be done at home with nurses + equipment
69
What is a Kidney transplant?
Cure for Kidney Failure - Healthy kidneys are transplanted from people who have died suddenly have to be organ donor (on register or carry donor card + family agree) - Alive people can also donate their kidneys
70
What are the pros and cons of Kidney transplants?
Cons: - small risk to donor (surgery risks) - Donor kidney can be rejected, new one needed - long waiting lists for kidneys Pros: - Cheaper in long run that dialysis
71
What are the main reproductive hormones for men and women?
Men- testosterone - testes, sperm production Women- Oestrogen - ovaries, physical changes (breasts etc), involved in the menstrual cycle
72
What are the stages of the menstrual cycle?
Stage 1: - Day 1, menstruation starts, uterus lining breaks down for 4 days Stage 2: - Day 4, uterus lining builds up for 10 days, thick spongy layer full of blood vessels to develop a fertilised egg Stage 3: - Day 14, egg develops and is released from ovary= OVULATION Stage 4: - Day 14, wall is maintained for 14 days. If no fertilised egg lands in the uterus wall, spongy lining starts to break down and whole cycle starts again.
73
What hormones is the menstrual cycle controlled by?
FSH Oestrogen LH Progesterone
74
What is Oestrogen?
- Produced in the ovaries - Causes lining of uterus to grow - Stimulates release of LH (causes release of egg) - Inhibits release of FSH
75
What is Progesterone?
-Produced at ovaries by remains of follicle after ovulation - Maintains lining of uterus during 2nd half of cycle - Levels of progesterone fall, lining breaks down - Inhibits release of LH and FSH
76
What is FSH (Follicle Stimulating Hormone)?
- Produced by pituitary gland - Causes egg to mature in one ovary (follicle) - Stimulates ovaries to produce oestrogen
77
What is LH (Luteinising Hormone)?
- Produced at the Pituitary gland - Stimulates release of egg (day 14) = Ovulation
78
How can Hormones be used to reduce fertility?
79
What are methods of contraception that use Hormones?
80
What is The Pill?
81
What is a contraceptive patch?
82
What is a contraceptive implant?
83
What is a contraceptive injection?
84
What is a intrauterine device (IUD)?
85
What are non-hormonal methods of contraception
86
What is Sterilisation?
87
What are 'Natural Methods' ?
88
What is Abstinence?
89
How can hormones be used to increase fertility?
90
What is IVF?
91
What are pros and cons of IVF?
92
Why are some people against IVF?
93
What is Adrenaline?
94
How does Thyroxine regulate Metabolism?
95
What is Thyroxine?
96
What is Auxin?
97
What is Phototropism?
98
What is Gravitropism?
99
What is happening when a shoot grown towards the light?
100
What is happening when a root grows towards the ground?
101
What are commercial uses of Auxins?
102
What is Gibberellin?
103
What are uses for Gibberellin?
104
What is Ethene?
105
What are uses for Ethene?

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