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Biology > 4.5 Homeostasis And Response > Flashcards

4.5 Homeostasis And Response Flashcards

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1
Q

What is homeostasis?

A

The regulation of the internal conditions of a cell or organism to maintain optimum conditions for functions in response to internal and external changes

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2
Q

What does homeostasis maintain in the human body?

A

Optimal conditions for enzyme action and all cell functions such as blood glucose concentration, body temperature,water levels

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3
Q

What are receptors and what do they do?

A

Cells that detect stimuli

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4
Q

What is a stimulus?

A

Changes in the internal or external environment

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5
Q

What are coordination centres and what do they do?

A

Areas such as the brain , spinal cord and pancreas that receive and process information from receptors

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6
Q

What are effectors and what do they do ?

A

Areas such as muscles and glands which bring about responses which restore optimum levels

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7
Q

What 2 things do the automatic control systems include ?

A

Nervous responses in your nervous system and chemical responses in your hormone system

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8
Q

What does the nervous system enable humans to do ?

A

To react to their surroundings and to coordinate their behaviour

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9
Q

How does the nervous system work ?

A

-information from receptors passes along sensory neurons () as electrical impulses to the centra nervous system (CNS). The CNS is the brain and spinal cord . The CNS coordinates the responses of effectors which may be muscles contracting or glands secreting hormaones

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10
Q
A
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11
Q

What are reflexes ?

A

Rapid automatic responses of the nervous system that do not involve conscious thoughts

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12
Q

What neurones do simple reflexes often have?

A

Sensory neurons,motor neurone,relay neurons-these connects a sensory neurone and a motor neurone and are found in the CNS

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13
Q

What is the reflex arc?

A

Bring about a reflex action . They involve the sense organ , sensory neurone relay neurone and motor neurone

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14
Q

Explain the reflex arc ?

A

Stimulus: A change in the environment is detected by receptors (e.g., skin).
Sensory Neuron: The receptor sends an electrical impulse to the spinal cord via a sensory neuron.
Relay Neuron: The impulse is passed to an interneuron in the spinal cord.
Motor Neuron: The interneuron sends the impulse to a motor neuron.
Effector: The motor neuron signals an effector (muscle or gland) to respond.
Response: The effector carries out the response (e.g., muscle contracts to move your hand away from a hot object).

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15
Q

What is the brain made up of and what does it do?

A

It controls complex behaviour and is made up of billions of interconnected neurones and has different regions that carry out different functions

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16
Q

What is the cerebral cortex and what does it control?

A

A regional of the brain which controls memory consciousness,language and intelligence

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17
Q

What is the cerebellum and what does it control?

A

It is a region in the brain which controls the coordination of muscular activity

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18
Q

What is the medulla nd what does it control?

A

A regional in the brain which controls unconscious activities such as breathing

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19
Q

What are some of the difficulties of investigating brain functions and treating brain damage and disease?

A
  • brain is complex and delicate
  • Most processes involve different neurones in different areas
  • Range of chemicals released
  • Brain can be easily damaged and destroyed
  • Dugs do not always reach the brain through the membranes
  • Not completely sure of what each area of the brain actually does
  • Easy to cause unintended damage
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20
Q

What is the eye?

A

A sense organ containing receptors sensitive to light intensity and colour

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21
Q

What is the sclera and what does it do?

A

The white out layer of the eye , it is fairly tough and strong so the ball is not easy to damage

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22
Q

What is the cornea and what does it do

A

Thetransparent area at the front of the eyeball which help refract light rays towards the retina

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23
Q

What is the retina and what does it do?

A

The retina is the light-sensitive layer at the back of the eye. It contains rods (for low light) and cones (for color and bright light). It converts light into electrical signals, which are sent to the brain via the optic nerve to create visual images.

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24
Q

What is the optic nerve and what does it do?

A

The optic nerve carries electrical signals from the retina to the brain, where the signals are processed to form visual images.

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25
What is the Iris and what does it do?
The iris is the colored part of the eye that controls the size of the pupil, regulating the amount of light entering the eye.
26
What is the ciliary muscle and what does it do?
Muscles that contract and relax to change the shape of the lens of the eye
27
What is the suspensory ligament and what does it do?
The ligaments that connect the lens of the eye to the ciliary muscles
28
What is accommodation?
The process of changing the shape of the lens to focus on near or distant
29
What happens to the eye if it needs to focus on a near object?
-the ciliarymuscles contract - the suspensory ligaments loosen -the lens is then thicker and refracts light rays strongly
30
What does the eye do if it needs to focus on a distant object?
-The ciliary muscles relax -the suspensory ligaments are pulled tight -the lens is the pulled thin and only slightly refracts light rays
31
What are the 2 common defects of the eyes?
Myopia(short sightedness)and hyperopia (long sightedness) in which rays of light do not focus on the retina
32
How can myopia and hyperopia treated?
With spectacle lenses which refracts the light rays so that they do focus on the retina
33
How do u treat myopia ?
To wear glasses with a concave lens that spread out the light from distant objects before it reaches the eye . This means the thicker lens can bring it into perfect focus on the retina
34
How can u treat hyperopia?
With glasses with a convex lens . They bring the light rays together more before they reach the eye itself . Now the thinner lens can bring the rays of light into perfect focus on the retina
35
What are the new technology’s used on the eye
Contact lenses Laser eye surgery Replacement lenses
36
What are contact lenses and what do they do ?
Lenses that are placed on the surface of the eye but
37
What is laser eye surgery?
Lasers are used to treat myopia by reducing the thickness of the cornea slit refracts the light less strongly to treat hyperopia lasers are used to change the curve of the cornea so it refracts light from close objects more effectively
38
What are replacement lenses?
A permanent contact lens is implanted into the eye and the natural lens is left in place . Another way is the faulty lens is replaced by an artificial lens .
39
What is the body temperature monitored and controlled by?
The thermoregulatory centre in the brain
40
What does the thermoregulatory centre contain?
Receptors sensitive to the temperature of the blood
41
What does receptors does the skin contain and what do they do?
Temperature receptors and sends nervous impulses to the thermoregulatory centre
42
What happens if body temperature is too high?
Blood vessels dilate (vasodilation) and sweat is produced from the sweat glands and these cause a transfer of energy from the skin to the environment
43
What happens if body temperature is too low?
Blood vessels constrict (vasoconstriction) sweating stops and skeletal muscles contract (shiver)
44
How does vasodilation lower your body temperature ?
Vasodilation lets more blood flow through the capillaries and your skin flushes so u transfer more energy by radiation to ur surroundings, cooling you down
45
How does sweating cools down down your body?
Sweating cools your body down as water evaporates from your skin transferring energy to the environment
46
How does vasoconstriction help raise your body temperature?
Reduces blood flow through capillaries so it reduces the energy transferred by radiation through the surface of your skin
47
How does lower sweat production help raise your body temperature?
Less water from sweat evaporates so less energy is transferred to the environment
48
How does shivering raise your body temperature?
Shivering needs a lot of respiration ,an exothermic process. The energy from these exothermic reactions raises your body temperature until shivering stops
49
What is the endocrine system?
The glands that produce the hormones that control many aspects of the development and metabolism of the body and the hormones they produce
50
What doe the glands from the endocrine system secrete and what do they do?
Hormones which go directly into the bloodstream . The blood then carries the hormone to a target organ where it produces an effect , compared to the nervous system the effects are slower but act for longer
51
What is the master gland in the brain
Pituitary gland
52
What does the pituitary gland do?
Secretes several hormones in turn act on other glands to stimulate other hormones to released to bring about effects
53
What is blood glucose concentration monitored and controlled by?
Pancreas
54
What happens if the blood glucose concentration is too high?
The pancreas produces the hormone insulin that causes glucose to move from the bloodstream into the cells.
55
What happens to excess glucose in the liver and muscle cells?
Excess glucose is converted to glycogen for storage
56
How does insulin control blood glucose levels in the body ?
causes glucose to move from the blood into the cells
57
What is type 1 diabetes?
A disorder in which the pancreas fails to produce sufficient insulin characterised by by uncontrolled high blood glucose levels
58
How is type 1 diabetes normally treated?
With insulin injections
59
What is type 2 diabetes?
A disorder in which the body cells no longer respond to insulin produced by the pancreas
60
How can type 2 diabetes be treated?
A carbohydrate controlled diet and an exercise regime are common treatments
61
What is a risk factor for type 2 diabetes?
Obesity
62
What happens if the blood glucose concentration is tool low?
The pancreas produces the hormone glucagon to be converted into glucose and released into the blood
63
How to cure type 1 diabetes?
Pancreas transplant and pancreatic cells transplant
64
How can u treat type 2 diabetes?
Eating a balanced diet Losing weight Doing regular exercise Medication
65
How does glucagon react with insulin in a negative feedback cycle to control blood glucose levels in the body?
Glucagon travels to the liver in the blood and causes the break-down of glycogen into glucose
66
How is water lost during exhalation?
Water leaves the body via the lungs during exhalation
67
What is lost through sweat?
Water , mineral ions and urea are lost through the skin in sweat
68
What is urea?
The nitrogenous waste product by the breakdown of excess amino acids in your liver
69
What is lost by no control?
Water through the lungs and water mineral ions and urea by the skin
70
How is excess water , ions and urea removed?
Via the kidneys in the urine
71
What happens if body cells lose or gain too much by osmosis?
They do not function properly
72
What does the digestion of proteins from the diet result in?
Excess amino acids which need to be excreted safely
73
What happens in the liver to the amino acids?
They are delaminated to form ammonia
74
What happens once ammonia is formed?
Ammonia is toxic so it is immediately converted to urea for safe extraction
75
How does the kidney produce urine?
By filtration of the blood and selective re absorption of useful substances such as glucose, some ions and water
76
What is ADH?
Anti diuretic hormone helps control the water balance of the body and effects the amount of urine produced by the kidney
77
What is selective reabsorption?
The process in the kidney where the materials needed in the body such as glucose , some mineral ions and water are reabsorbed back into the blood filtrate
78
What hormone is the water level in the body controlled by?
ADH which acts on the kidney tubules
79
What is ADH released by and when and what does it do?
By the pituitary gland when the blood is too concentrated and it causes more water to be reabsorbed back into the blood from the kidney tubules
80
How can kidney failure be treated?
By organ transplant or by using kidney dialysis
81
What is dialysis?
The process of cleansing the blood through a dialysis machine when the kidney fails
82
What happens ina dialysis machine?
The concentration of dissolved substances in the blood is restored to normal levels
83
What does reproductive hormones during puberty cause?
Secondary sex characteristics to develop
84
Where is oestrogen produced?
In the ovaries
85
What is ovulation?
At puberty eggs begin to mature and one is released approximately every 28days
86
Where is testosterone produced and what does it do?
Testosterone isthe main male reproductive hormone produced by the testes and it stimulates sperm production
87
What are some hormones involved in the menstrual cycle?
Follicle stimulating hormone (FSH)Luteinising hormone (LH) Oestrogen and progesterone
88
What does FSH do?
Causes maturation of an egg in the ovary
89
What does LH do ?
Stimulates the release of the egg
90
What does oestrogen and progesterone do?
Involved in maintaining the uterus lining
91
How can fertility be controlled?
By a variety of hormonal and non hormonal methods of contraception
92
What are some methods of contraception?
Oral contraceptives Injections implant or skin patch Barrier methods aka condoms and diaphragms Intrauterine devices Spermicidal agents Abstaining from intercourse Surgical methods
93
How do oral contraceptives work?
They contain hormones to inhibit FSH production so that no eggs mature
94
How do injections implants or skin patches work?
The slowly release progesterone to inhibit the maturation and release of eggs for a number of months or years
95
How do barrier methods work?
They prevent the sperm reaching the egg
96
How do intrauterine devices work?
Prevent the implantation of an embryo or release a hormone
97
How do spermicidal agents work?
It kills or disables sperm
98
What is IVF?
In VitroFertilisation?
99
How does IVF work?
Giving a mum FSH and LH to stimulate the maturation of several eggs The eggs are collected from the mother and fertilised by sperm from the dad in the lab The eggs develop into embryos When they are tiny balls of cells 1 or 2 embryos are inserted into the mothers uterus womb
100
What are some disadvantages to IVF?
It is very emotional and physically stressful The success rates are not high It can lead to multiple births which are a risk to both the babies and mum
101
Where and when is adrenaline produced?
By the adrenal glands in times of fear or stress
102
What does adrenaline do?
It increases the heart rate and boosts the delivery of oxygen and glucose to the brain and muscles, preparing the body for fight or flight
103
Where is thyroxine produced and what does it stimulate?
The thyroid gland and I stimulates the basal metabolic rate and it plays an impor role in growth and development
104
What is thyroxine controlled by?
Negative feedback
105
Why do plants produce hormones?
To coordinate and control growth and responses to light (phototropism)and gravity (geotropism)
106
What is auxin?
A plant hormone that controls the responses of plants to light and gravity
107
What are gibberellins?
Plant hormones that are important in initiating seed germination
108
What are gibberellins important for?
Initiating seed germination
109
What does ethane control?
Cell division and ripening of fruits
110
What are plant hormones used in?
Agriculture and horticulture
111
What are auxins used for?
As weed killers As rooting powders For promoting growth in tissue culture
112
What is ethane used in?
The food industry to control ripening of fruit during storage and transport
113
What can gibberellins be used for?
End seed dormancy Promote flowering Increase fruit size

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