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biology > homeostasis and response > Flashcards

homeostasis and response Flashcards

1
Q

What is homeostasis?

A

Maintenance of a constant internal environment in order to maintain optimum conditions for enzymes and cellular function

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2
Q

Give examples of conditioned maintained by homeostasis in the body

A

blood glucose concentration
Body temperature
Water levels

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3
Q

What two types of responses are used in body control systems?

A

Nervous and chemical

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4
Q

What 3 components do all control systems have?

A

receptors
Coordination centres
effectors

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5
Q

what is the function of a receptor?

A

Receptors detect changes in the environment

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6
Q

What is the function of a coordination centre?

A

Coordination centres obtain and process information from receptors

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7
Q

what is the function of an effector

A

Bring about response to stimuli

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8
Q

What is the function of the nervous system?

A

The nervous system allows the body to react to its surroundings and coordinate an appropriate response

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9
Q

How does a stimulus lead to response being carried out by the body?

A

stimulus is converted into an electrical impulse by the receptors

The electrical impulse passes along century neurons to the central nervous system

The CNS coordinate an appropriate response and an electrical impulse is sent along motor neurons to the effector, which carries out the response 

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10
Q

what sequence of events describes how the nervous system works? 

A

stimulus——>receptor——->coordinator——>effector——>response

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11
Q

what is a reflex action?

A

A reflex action is an automatic and rapid response, which does not involve any conscious input from the brain

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12
Q

why are reflex actions important?

A

Reflex actions a survival by preventing harm to the body

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13
Q

describe how reflex action occurs via a reflex arc

A

The stimulus is detected by a receptor

An electrical impulse passes along a sensory neuron to the spinal cord

At a pace between a sensory neuron and a relay neuron, a chemical diffusers across the gap and stimulates a new impulse which passes along the relay neurone

The same process occurs at a centipedes between a relay neuron and motor neuron

At the effector an appropriate response is carried out

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14
Q

What is the difference between a reflex pathway and a conscious pathway?

A

Within a reflex pathway, the coordination centre is a relay neuron found in the spinal cord unconscious parts of the brain. In a conscious pathway, the coordination centre is the conscious part of the brain.

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15
Q

What is the function of the cerebral cortex?

A

Controls consciousness, intelligence, memory and language

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16
Q

What is the function of the cerebellum?

A

Controls muscular coordination

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17
Q

what is the function of the medulla

A

Controls unconscious activities, e.g. breathing, heart rate

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18
Q

why is the investigation and treatment of the brain difficult?

A

The brain is a complex and delicate organ

The brain is easily damaged and destroyed

Certain membranes prevent drugs from reaching the brain

The exact function of each part of the brain is not known

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19
Q

what methods are used by scientists determine brain function?

A

Studying patients with brain damage

Electrical stimulation of the brain

MRI scans

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20
Q

what stimuli are the receptors of the is sensitive to?

A

Light intensity and colour

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21
Q

What are the two main functions of structures found within the eye?

A

focusing on near or distant objects
Adaptation to dim light

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22
Q

describe the structure and function of the retina

A

The retina is a light sensitive layer found at the back of the eye

light stimulates the retinal cells, resulting in impulses being sent to the brain 

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23
Q

describe the structure and function of the optic nerve

A

The optic nerve connects the eye and the brain

It carries impulses to the brain so that an image can be visualised

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24
Q

describe structure and function of the sclera

A

the sclera is the tough outer layer of the eye which protects its internal structures

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25
Q

Describe the structure and function of the cornea

A

The cornea is the curved transparent layer at the front of the eye

It lets light into the eye and allows light to be focused on to the retina

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26
Q

describe the structure and function of the iris

A

The iris is a muscle which controls the size of the pupil by contracting or relaxing. This allows the eye to adjust to the bright and dim light.

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27
Q

describe the structure and function of the ciliary muscles and suspensory ligaments 

A

the ciliary muscles and suspensory ligament hold the lens in place and control its shape

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28
Q

Describe how that iris alters the size of the pupil in both bright and dim light

A

bright light: circuit muscles, contract and radial muscles relax – makes pupil smaller to avoid retinal damage

dim light: circuit muscles relax and radio muscles contract – makes pupil larger so more light can enter the eye

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29
Q

what is accommodation?

A

Accommodation is the alteration of the lens shape in order to focus on near or distant objects

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30
Q

how does the eye focus on a nearby object?

A

ciliary muscles contract

suspensory ligaments loosen

lens becomes thicker and more curved -light rays are refracted strongly

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31
Q

How does the eye focus on a far away object?

A

ciliary muscles relax
suspensory ligaments tighten
lens becomes thinner -light rays are refracted weakly

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32
Q

what is a myopia

A

Usually occurs when the lens of the eye is too curved. As a result, light is focused in front of the retina and show images of blurry.

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33
Q

how can myopia be treated

A

using glasses with a concave lens, which spreads out light rays so they could be focused on the retina

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34
Q

what is hyperopia

A

usually occurs when the lens of the eye is too flat. As a result, the light is focused behind the retina so images appear out of focus. 

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35
Q

how can hyperopia be treated

A

using glasses with a convex lens, which brings the light raises together so they can be focused on the retina

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36
Q

what are the two types of contact lenses?

A

hard – rigid material, last long time, must be kept sterile

Soft – flexible material, last short time, more comfortable

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37
Q

What is a laser eye surgery?

A

laser eye surgery is the use of lasers to fix defects in adults.

To treat myopia, laser reduce the thickness of the cornea so light is refracted less strongly.

The treat hyperphoria lasers alter the curvature of the so that light is refracted correctly. 

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38
Q

how can replacement lenses be used to treat visual defects?

A

Replacement implanted into the eye or it may replace the natural lens altogether. Risk of the reliance replacement include retinal damage cataracts, and infection.

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39
Q

What are the risk of lens replacement?

A

Retinal damage, cataracts, and infections

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40
Q

where is the body temperature controlled in the body?

A

Body temperature is controlled by the Thermo regulator centre in the hypothalamus of the brain

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41
Q

how is the temperature monitored by your body?

A

Thermo regulator centre has receptors sensitive to blood temperature

Skin has receptor sensitive to skin temperature – send impulses to Thermo regulator

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42
Q

What physiological changes occur when the body temperature is too high?

A

vasodilation – blood vessels near the surface of the skin dilate –more heat is radiated away

Sweating – evaporation of water takes away heat energy from the surface of the skin

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43
Q

What physiological changes occur when the body temperature is too low?

A

vasoconstriction-blood vessels near the surface of the skin constrict – less heat radiated away

Shivering – respiration allows muscles to contract. It is an exothermic process, so he energy is released.

Sweating stops

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44
Q

give the name of the bodies coordination system which involves hormones

A

The endocrine system

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45
Q

what is a hormone?

A

A hormone is a chemical messenger secreted by a gland. It travels in the blood to a target organ, where it causes a response.

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46
Q

what type of organ secretes hormones

A

Glands

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47
Q

Which gland controls many other glands in the body?

A

the pituitary gland

48
Q

why is the pitunitary gland considered a master gland

A

it secrets a wide range of hormones,some which may stimulate other endocrine glands

49
Q

What is the role of the pitcunitary gland in the endocrine system?

A

secretes human growth hormone – controls human growth

Stimulates the thyroid gland

Stimulates the ovulation and the production of oestrogen in the ovaries

The production of sperm and testosterone in the testes

50
Q

What is the role of the thyroid gland in the endocrine system?

A

Secretes the hormone thyroxine – controls metabolism, heart rate and body temperature

51
Q

what is the role of the pancreas in the endocrine system?

A

Secretes the hormone insulin – controls blood glucose levels

52
Q

what is the role of the adrenal gland in the endocrine system?

A

Secrets adrenaline – controls the body flight or fight response

53
Q

What is the role of the ovaries in the endocrine system?

A

Secret oestrogen, which coordinates the mental cycle and the development of female secondary sexual characteristics

54
Q

what is the role of the testes in the endocrine system?

A

Secretes testosterone, which coordinates the production of sperm and the development of a male secondary sexual characteristics

55
Q

which organ monitoring controls blood glucose concentration?

A

The pancreas

56
Q

How does the pancreas respond when blood glucose levels are too high?

A

The pancreas secretes the hormone insulin. Insulin binds to receptors on the liver and muscles, causing access glucose to be converted into glycogen installed.

57
Q

How does the pancreas respond when blood glucose levels are too low

A

The pancreas secretes the hormone glucagon. Glucagon binds to liver cells, causing glycogen to be converted into glucose and released into the blood.

58
Q

Blood glucose concentration controlled using a negative feedback loop

A

when the blood glucose concentration rises and falls below the optimum, a hormone is secreted by the pancreas

The action of either hormone insulin or glucagon helps bring back the concentration to the correct level

59
Q

what is type one diabetes?

A

Type one diabetes is an autoimmune disorder in which the parent does not produce sufficient insulin to control the blood glucose concentration. As a result blood glucose levels are often very high to, leading to excessive urination, tightness and weight loss

60
Q

how can type one diabetes be treated?

A

Insulin injections before meals – allows glucose to be converted into glycogen

Limiting carbohydrate intake

Attempts using pancreas and pancreatic cell transplant: investigations into genetic engineering of pancreatic cells

61
Q

What is type two diabetes?

A

Type two diabetes is a disorder in which the body cells stop responding to insulin, leading to an uncontrolled blood glucose concentration. Its answer is linked with increasing age and obesity.

62
Q

how can type two diabetes be treated?

A

Following a careful controlled diet

Doing regular exercise

Losing weight

Use of drugs which increase in insulin production and effectiveness

63
Q

in what ways is water loss from the body?

A

During exhalation via the lungs

Sweating

Urine

64
Q

In what ways are ions lost from the body?

A

sweating

Urine

65
Q

how are excess amino acids excreted from the body?

A

Access amino acids are deaminated in liver to form ammonia

ammonia is toxic, therefore it is converted into urea

Urea is excreted from the body via sweat and urine

66
Q

how do kidneys maintain the balance of water and other substances in the body?

A

Filter blood in order to remove waste products, e.g. urea

Selectively reabsorb useful molecules e.g. glucose, water, ions

67
Q

What is the full name of the hormone ADH?

A

anti-diuretic hormone

68
Q

where isADH secreated in the body?

A

The pituitary gland

69
Q

how does ADH affect the absorption of water in the kidneys?

A

When the blood is too concentrated, the pituitary gland secretes more ADH

ADH travels into the blood trim to the kidneys and increases the permeability of kidney tubules to water

More water is reabsorbed in the kidneys resulting in a smaller volume of more concentrated urine

70
Q

 why is kidney failure dangerous?

A

when the kidneys are damaged, they may be unable to fill other blood properly. This may lead to:

A buildup of toxic molecules in the body

An uncontrolled ion and water balance and cells being damaged as a result of osmosis

71
Q

What are two main ways of treating kidney failure?

A

Dialysis and transplant

72
Q

what is kidney dialysis?

A

Kidney dialysis is the use of a specialist machine to carry out the function of kidneys.

Fluid contains the same concentration of glucose and ions as a healthy blood

As a result, only excess and waste molecules are lost from the blood and glucose and irons remain

73
Q

what is the main function of reproductive hormones during puberty?

A

Males: characterised development of secondary sexual characteristics
Females: causes the development of secondary sexual characteristics and the maturation of eggs

74
Q

What is the main male reproductive hormone

A

Testosterone which is produced by the testes and control sperm production

75
Q

What is the main female reproductive hormone?

A

Easter room which is produced by the ovaries and is involved in the menstrual cycle

76
Q

what is the menstrual cycle?

A

is the monthly cycle of physiological changes that occur in females, involving the shedding of the uterus lining and ovulation

77
Q

describe the events of the menstrual cycle

A

Uterus lining thickens and eggs begin to mature in the ovaries

an egg release from one of the ovaries – uterus lining remains thick

If the egg is fertilised pregnancy may occur if not both the egg and the uterus lining are shed during menstruation

78
Q

what is ovulation?

A

Ovulation is the release of a mature egg from the ovaries which occurs approximately every 28 days

79
Q

name the four main hormones involved in the menstrual cycle

A

Oestrogen
Progesterone
Follicle stimulation hormone FSH
luteinising hormone LH

80
Q

What is the role of FSH in the mental cycle?

A

FSH is secreted by the pit gland. It controls the maturation of eggs within the ovaries and triggers the production of eastern by the ovaries.

81
Q

What is the role of oestrogen in the menstrual cycle?

A

Oestrogen is produced by the ovaries and is released due to the action of FSH – it causes the regrowth of the uterus lining

Production of LH and restrictive release of more FSH

82
Q

What is the role of LH in the menstrual cycle?

A

LH is produced in the pit territory gland as it result of oestrogen it’s release triggers ovulation

83
Q

What is the role of progesterone in the menstrual cycle?

A

progesterone is secreted from the molecule of the ovary. It sustained the uterus lining and inhibits FSH and LH

84
Q

What are the two types of oral contraceptives?

A

combined contraceptive pill – contains oestrogen and progesterone

Mini pill – contains only progesterone

85
Q

How does the contraceptive pill prevent pregnant pregnancy?

A

inhibit FSH – eggs do not mature

Prevents the development of the uterus learning – eggs cannot implant

Increases the thickness of cervical mucus – immobilises sperm cells

86
Q

What is the contraceptive patch?

A

contains both oestrogen and progesterone

It is a patch that is placed onto the skin for seven days at a time

87
Q

what is the contraceptive implant?

A

A small rod inserted under the skin which continuous releases the hormone progesterone – last three years

88
Q

What is the contraceptive injection?

A

An injection containing the hormone progesterone – last for approximately three months

89
Q

What is the iUS

A

Is a small plastic device that is inserted into the uterus. It releases progesterone which thicken cervical mucus and prevents the buildup of the uterine lining.

90
Q

what is the iud

A

Small copper containing device inserted into the uterus, which prevents the implantation of embryos

91
Q

What is spermicide?

A

A chemical that kills are immobilised sperm cells – however they are not very effective and work better when combined with barrier methods

92
Q

what is a barrier method of contraception?

A

Condoms
Diaphragms

93
Q

what surgical methods of contraception are available?

A

Sterilisation – in males are sperm ducks are tied and in females oviducts are tied

94
Q

What is abstinence?

A

The practice of not having sex, which also avoid pregnancy. Some people abstain from sex around the time of ovulation – this is known as The Rhythm Method.

95
Q

how do you fertility drugs increase the chance of pregnancy?

A

Many fertility drug contain FSH – which stimulates oestrogen production and the maturation of eggs in the ovary. They also contain LH which triggers ovulation.

96
Q

what is IVF?

A

Mother is given FSH and LH – in maturation of eggs and ovulation

eggs are fertilised using sperm in a laboratory – develop into embryos

One or two embryos are inserted into the mother’s womb

97
Q

what are the advantages of fertility treatment?

A

Allows infertile couples to have children

Can store women’s eggs for later

98
Q

what are the disadvantages of fertility treatment?

A

It can be very expensive process

It has low success rate – especially for older couples

Increases chance of multiple pregnancies – dangerous for mother and babies

Side effects of fertility drugs

99
Q

What is negative feedback?

A

Negative feedback is a type of control whether the body responds to an increase or decrease in a factor by returning it to optimum level

100
Q

What is thyroxine?

A

thyroxine is a hormone released by the thyroid gland. It’s release is triggered by the thyroid stimulation hormone. Thyroxine controls the body metabolic rate growth and development.

101
Q

how is the release of thyroxine controlled by negative feedback?

A

levels of blood thyroxine falls – detected by receptors in the brain

pituitary gland releases more TSH

more thyroxine produced and released by thyroid gland

blood thyroxine levels return to normal

102
Q

What is adrenaline?

A

Adrenaline is a hormone secreted by the adrenaline and gland in times of stress it is responsible for the fight or flight response

103
Q

What are the effects of adrenaline?

A

increases in heart and breathing weight – delivers oxygen and glucose to the body

Stored glycogen converted into glucose

Dilation of pupils

Increased mental awareness

Blood diverted away from digestive system to muscles

104
Q

what is tropism?

A

Response of a plant to specific stimulus

105
Q

What is phototropism?

A

phototropism is the response of a plant shoot or root to light

106
Q

what is gravitopism

A

The response of a plant shoot or root to gravity

107
Q

what is auxin

A

Hormone which controls the growth of a plant shoots or roots when oxygen is unevenly distributed in a growing plant the rate of growth will be unequal

108
Q

How do plant shoots show positive phototropism?

A

One side of the shoot is in light, causing auxin to move to the shaded side

at the shaded side, the cells are stimulated to grow – the shoot bends towards a light

As a result, photosynthesis can occur faster rate

109
Q

how do plant shoots show negative gravitropism

A

In a horizontal shoot, auxin accumulate in the lower side due to gravity

cells on the lower side of shoot grower causing the shoot to bend away from the direction of gravity

As a result, more light is usually available for photosynthesis

110
Q

how do plant roots show positive gravitropism

A

in a horizontal root ,auxin accumulates in the lower side, causing cells to grow less

The root bends in direction of gravity

As a result, more water and nutrients are available to the plant roots

111
Q

what are gibberellins

A

type of plant hormone involved in seed germination

112
Q

What is ethene

A

Type of plant hormone involved in cell division and ripening

113
Q

what are the uses of auxins

A

Weed killer – causes cells to grow at a rapid rate, causing plant death

Rooting powder – causes new plant to grow very quickly

Tissue culture – promotes growth of roots and shoots

114
Q

what are the uses of ethene

A

Control of food ripening in the food industry – allows fruit to be ripen just before they are sold

115
Q

what are the uses of gibberellins

A

termination of seed dormancy

Promotional flowering

Increase of fruit size

biology (10 decks)

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