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Bio P2 > Homeostasis > Flashcards

Homeostasis Flashcards

1
Q

What is homeostasis

A

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

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2
Q

Conditions maintained by homeostasis in the body

A
  • blood glucose conc
  • body temp
  • water levels
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3
Q

Two responses used in control systems

A

Nervous
Chemical

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4
Q

Receptor functions

A

Detects changes in environment ( stimuli )

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5
Q

Functions of coordination Center

A

Obtain and process information from receptors

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6
Q

Function of effector

A

(Muscles or glands ) bring about responses to stimuli

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7
Q

Function of nervous system

A

Allows body to react to surrounding and coordinate appropriate response

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8
Q

How stimulus leads to a response

A

Receptor- convert stimulus into electrical impulse
Passed along sensory neurones to CNS
CNS coordinates response and electrical impulse sent along motor neurones to the effector which carries out the response

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9
Q

Nervous system order events

A

Stimulus
Receptor
Coordinator
Effector
Response

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10
Q

Reflex action

A

Automatic and rapid response which doesn’t involve any conscious input from the brain

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11
Q

Describe reflex arc

A

Stimulus detected by receptor
Electrical impulse passes along sensory neurons to spinal cord
At a synapse (btw sensory and relay neurone ) chemical diffuses across gap stimulating a new impulse which passes along relay neurone
Same process at synapse between relay and motor
At effector , response carried out

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12
Q

Reflex pathway and conscious pathway

A

Reflex - coordination centre is relay neurone in spinal cord ( unconscious parts of the brain )
Conscious - coordination Centre is in conscious part of the Brain

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13
Q

Cerebral cortex function

A

Controls consciousness, intelligence, memory and language

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14
Q

Function of cerebellum

A

Controls muscular co ordinatiom

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15
Q

Function of medulla

A

Controls unconscious activities like breathing / heart rate

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16
Q

Why is investigation of brain difficult

A

Complete and delicate organ
Easily damaged and destroyed
Certain membranes prevent drugs from reaching the brain
Exact function of each part of the brain is not known

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17
Q

Methods to determine brain function

A
  • studying patients with brain damage
  • electrical stimulation of the brain
  • MRI scans
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18
Q

Which stimuli are receptors of the eye sensitive to

A

Light intensity
Colour

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19
Q

Two main function in eye

A

Focusing on near/ distant objects - accommodation

Adaption to dim light

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20
Q

Structure and function of retina

A

Light sensitive layer at back of the eye
Light stimulates retinal cells = impulses sent to the brain

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21
Q

Structure and function of optic nerve

A

Connects eye and brain

Carries impulses to brain so an image can be visualised

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22
Q

Describe the 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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23
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 onto the retina.

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24
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 bright and dim lighting

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25
Q

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

A

The ciliary muscles
and suspensory
ligaments hold the lens in place and control its shape.

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26
Q

Describe how the iris alters the size of the pupil in both bright and dim light (biology only)

A

• Bright light: circular muscles contract and radial muscles relax - makes pupil smaller to avoid retinal damage.
• Dim light: circular muscles relax and radial muscles contract - makes pupil larger so more light can enter the eye.

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27
Q

What is accommodation? (biology only)

A

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

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28
Q

How does the eye focus on a nearby object?

A

• Ciliary muscles contract= smaller diameter
• Suspensory ligaments loosen.
• Lens becomes thicker and more curved so more convergent- light rays are refracted strongly.

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29
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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30
Q

What is myopia? (biology only)

A

Myopia (shortsightedness) usually occurs when the lens of the eye is too curved. As a result, light is focused in front of the retina so images appear blurry.

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31
Q

How can myopia be treated? (biology only)

A

Myopia can be treated using glasses with a concave lense, which spreads out light rays so they can be focused on the retina.

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32
Q

What is hyperopia? (biology only)

A

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

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33
Q

How can hyperopia be treated? (biology only)

A

Hyperopia can be treated using glasses with a convex lense, which brings the light rays together so they can be focused on the retina

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34
Q

What are the two types of contact lenses?
(biology only)

A

• Hard - rigid material, last a long time, must be kept sterile.
• Soft - flexible material, last for a shorter time, more comfortable.

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35
Q

What is laser eye surgery? (biology only)

A

Laser eye surgery is the use of lasers to fix visual defects in adults.
myopia, lasers reduce the thickness of the cornea so light is refracted less strongly.
hyperopia, lasers alter the curvature of the cornea so that light is retracted correctly.

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36
Q

How can replacement lenses be used to treat visual defects? (biology only)

A

A replacement lens can either implanted into the eye (along with the natural lens) or it may replace the natural lens altogether. Risks of lens replacement include retinal damage, cataracts and infections.

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37
Q

Where is body temperature controlled in the body? (biology only)

A

Body temperature is controlled by the thermoregulatory centre in the hypothalamus of the brain.

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38
Q

How is temperature monitored by the body?
(biology only)

A

• Thermoregulatory centre has receptors sensitive to blood temperature.
• Skin has receptors sensitive to skin temperature - sends impulses to thermoregulatory centre.

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39
Q

What physiological changes occur when the body temperature is too high? (biology only)

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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40
Q

What physiological changes occur when the body temperature is too low? (biology only)

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 heat energy is released.
• Sweating stops.

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41
Q

Explain why temp near brain decreased

A

Blood is cooled at stomach/ mouth then flows to brain

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42
Q

Why do marathon runners drink sports drinks during a race

A

To replace water ions salt lost in sweat

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43
Q

3 ways endocrine system is diffenert to nervous system

A

Endocrine is slower, longer lasting and via bloods not neurones

44
Q

Describe how brain receives information about light entering the eye

A

Retina detects light
Impulse passed along sensory neurone along optic nerve

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.

46
Q

What type of organ secretes hormones?

A

Glands

47
Q

Which gland controls many other glands in the body?

A

The pituitary gland

48
Q

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

A

• Secretes human growth hormone - controls human growth.
• Stimulates the thyroid gland.
• Stimulates ovulation and the production of ostrogen in the ovaries.
• Stimulates the production of sperm and testosterone in the testes.

49
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.

50
Q

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

A

Secretes the hormone insulin - controls blood glucose levels.

51
Q

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

A

Secretes adrenaline - controls the body’s
‘fight or flight’ response.

52
Q

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

A

Secrete estrogen, which coordinates the menstrual cycle and the development of female secondary sexual characteristics.

53
Q

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

A

Secrete testosterone, which coordinates the production of sperm and the development of male secondary sexual characteristics.

54
Q

Which organ monitors and controls blood glucose concentration?

A

The pancreas

55
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 excess glucose to be converted into glycogen and stored.

56
Q

How does the pancreas respond when blood glucose levels are too low? (higher only)

A

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

57
Q

How is blood glucose concentration controlled using a negative feedback loop? (higher only)

A

• When the blood glucose concentration rises or 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.

58
Q

In what ways is water lost from the body? (biology only)

A

• During exhalation via the lungs
• Sweating
• Urine (some reabsorbed in the kidney)

59
Q

How are excess amino acids excreted from the body? (biology only) (higher only)

A

• Excess amino acids are deaminated in the liver to form ammonia.
• Ammonia is toxic, therefore it is converted into urea
• Urea is excreted from the body via sweat and urine.

60
Q

How do the kidneys maintain the balance of water and other substances in the body? (biology only)

A

• Filter blood in order to remove waste products eg. urea.
• Selectively reabsorb useful molecules eg. glucose, water, ions.

61
Q

How does ADH affect the reabsorption of water in the kidneys? (biology only) (higher only)

A

• When the blood is too concentrated, the pituitary gland secretes more ADH.
• ADH travels in the bloodstream to the kidney 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.

62
Q

Where is ADH secreted in the body?

A

The pituitary gland of the brain

63
Q

Why is kidney failure dangerous? (biology only)

A

When the kidneys are damaged, they may be unable to filter the blood properly. This may lead to:
• A build-up of toxic molecules (eg. urea) in the body.
• An uncontrolled ion and water balance and cells being damaged as a result of osmosis.

64
Q

What are the two main ways of treating kidney failure? (biology only)

A

• Dialysis
• Transplant

65
Q

What is kidney dialysis? (biology only)

A

Kidney dialysis is the use of a specialist machine to carry out the function of kidneys. Dialysis fluid contains the same concentration of glucose and ions as healthy blood. As a result, only excess and waste molecules are lost from the blood, and glucose and ions remain.

66
Q

What is kidney dialysis? (biology only)

A

Kidney dialysis is the use of a specialist machine to carry out the function of kidneys. Dialysis fluid contains the same concentration of glucose and ions as healthy blood. As a result, only excess and waste molecules are lost from the blood, and glucose and ions remain.

67
Q

What is the function of reproductive hormones during puberty?

A

• Males: cause the development of secondary sexual characteristics.
• Females: cause the development of secondary sexual characteristics and the maturation of eggs.

68
Q

What is the main male reproductive hormone?

A

The main male reproductive hormone is testosterone, which is produced by the testes and controls sperm production.

69
Q

What is the main female reproductive hormone?

A

The main female reproductive hormone is estrogen, which is produced by the ovaries and is involved in the menstrual cycle.

70
Q

What is the menstrual cycle?

A

The menstrual cycle is the monthly cycle of physiological changes that occur in females, involving the shedding of the uterus lining (menstruation) and ovulation.

71
Q

Describe the events of the menstrual cycle

A

• Uterus lining thickens and eggs begin to mature in the ovaries.
• An egg is released from one of the ovaries (ovulation)
- 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.

72
Q

What is ovulation?

A

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

73
Q

Name the four main hormones involved in the menstrual cycle

A

• Oestrogen
• Progesterone
• Follicle stimulating hormone (FSH)
• Luteinising hormone (LH)

74
Q

What is the role of FSH in the menstrual cycle? (higher only)

A

FSH is secreted by the pituitary gland. It controls the maturation of eggs within the ovaries (inside a follicle) and triggers the production of ostrogen by the ovaries.

75
Q

What is the role of ostrogen in the menstrual cycle? (higher only)

A

Oestrogen is produced by the ovaries and released due to the action of FSH - it causes the regrowth of the uterus lining.
It triggers the production of LH and restricts the release of more FSH.

76
Q

What is the role of LH in the menstrual cycle? (higher only)

A

LH is produced in the pituitary gland as a result of estrogen. Its release triggers ovulation.

77
Q

What is the role of progesterone in the menstrual cycle? (higher only)

A

Progesterone is secreted from the follicle of the ovary. It sustains the uterus lining and inhibits FSH and LH.

78
Q

What is contraception?

A

Contraception refers to any method of preventing pregnancy.

79
Q

What are the two types of oral contraceptives?

A

• Combined contraceptive pill (contains estrogen and progesterone).
• Mini pill (contains only progesterone).

80
Q

How does the contraceptive pill prevent pregnancy?

A

• Inhibits FSH - eggs do not mature.
• Prevents the development of the uterus lining - eggs cannot implant.
• Increases the thickness ot cervical mucus - immobilises sperm cells.

81
Q

What is the contraceptive patch?

A

• Contains both ostrogen and progesterone.
• It is a patch that is placed onto the skin for 7 days at a time.

82
Q

What is the contraceptive implant?

A

A small rod inserted under the skin which continuously releases the hormone progesterone - lasts for 3 years.

83
Q

What is the contraceptive injection?

A

An injection containing the hormone progesterone - lasts for approximately 3 months.

84
Q

What is the IUS?

A

The IUS (intrauterine system) is a small plastic device that is inserted into the uterus. It releases progesterone which thickens cervical mucus and prevents the build-up of the uterine lining.

85
Q

What is the IUD?

A

The IUD (intrauterine device) is a small copper-containing device inserted into the uterus, which prevents the implantation of embryos.

86
Q

What is a spermicide?

A

A spermicide is a chemical that kills or immobilises sperm cells - however, they are not very effective, and work better when combined with barrier methods.

87
Q

What is a barrier method of contraception?

A

A barrier method of contraception involves a physical separation between the sperm and the egg. They include:
• Condoms - thin sheath worn on the penis or inside the vagina - protects against STIs but may tear/break.
• Diaphragms - a thin cap placed over the cervix - prevent entry of sperm.

88
Q

What surgical methods of contraception are available?

A

Sterilisation - in males, the sperm ducts are tied (vasectomy) and in females, the oviducts are tied.

89
Q

What is abstinence?

A

Abstinence is the practice of not having sex, which also avoids pregnancy. Some people abstain from sex around the time of ovulation - this is known as the rhythm method, but it is quite unreliable.

90
Q

How do fertility drugs increase the chance of pregnancy? (higher only)

A

Many fertility drugs contain FSH - which stimulates estrogen production and the maturation of eggs in the ovary. They also contain LH which triggers ovulation.

91
Q

What is IVF? (higher only)

A

(in vitro fertilisation) is type of fertility treatment:
• Mother is given FSH and LH - stimulates maturation of eggs and ovulation.
• Eggs are fertilised using sperm in a laboratory - develop into embryos.
• 1 or 2 embryos are inserted into the mother’s womb.

92
Q

What are the advantages of fertility treatment?
(higher only)

A

• Allows infertile couples to have children
• Can store a woman’s eggs for later

93
Q

What are the disadvantages of fertility treatment?
(higher only)

A

• It can be a very expensive process.
• It has a low success rate - especially for older couples.
• Increases chance of multiple pregnancies - dangerous for mother and babies.
• Side effects of fertility drugs.

94
Q

What is negative feedback? (higher only)

A

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

95
Q

What is thyroxine? (higher only)

A

Thyroxine is a hormone released by the thyroid gland. Its release is triggered by the thyroid stimulating hormone (TSH). Thyroxine controls the body’s metabolic rate, growth and development.

96
Q

How is the release of thyroxine controlled by negative feedback? (higher only)

A

• Levels of blood thyroxine falls - detected by receptors in the brain.
• Pituitary gland releases more TSH.
• More thyroxine produced and released by the thyroid gland.
• Blood thyroxine level returns to normal.

97
Q

What is adrenaline? (higher only)

A

Adrenaline is a hormone secreted by the adrenal gland in times of stress. It is responsible for the ‘fight or flight response

98
Q

What are the effects of adrenaline? (higher only)

A

• Increase in heart and breathing rate - delivers oxygen and glucose to the body.
• Stored glycogen converted to glucose.
• Dilation of pupils.
• Increased mental awareness.
• Blood diverted away from digestive system to muscles.

99
Q

How is type 1 diabetes managed?

A

Inject insulin
Monitor diet
Exercise regularly

100
Q

type 1 diabetes

A

pancreas fails to produce enough insulin

101
Q

type 2 diabetes

A

cells no longer respond to insulin

102
Q

treatments of type 2 diabetes

A

controlled diet
exercise regime

103
Q

minerals reabsorbed in selective reabsorption

A

all glucose
some water

104
Q

deamination

A

If the body has more acids than it needs, it can convert them into lipids or , which can be stored as an energy source for later.

105
Q

what does release of ADH do

A

released by pituitary gland when blood is too concentrated , causes more water to be reabsorbed back into blood by kidney tubules
controlled by negative feedback

106
Q

oral contraceptives

A

inhibit FSH, no eggs mature

107
Q

injection,implan or patch

A

slow release of progesterone to inhibit maturing / releasing of eggs

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