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(A) Biology > B3 > Flashcards

B3 Flashcards

1
Q

How do nerve impulses travel through your nervous system (conscious)

A

Stimulus → Receptor cells → sensory neurone → Spinal cord → Brain → Spinal cord → motor neurone → Effector response

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2
Q

What do relay neurones do

A

Carry electrical impulses from sensory neurons to your motor neurons

And from the spinal cord to motor neurones

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3
Q

What is the reflex arc

A

The pathway of an impulse during a reflex reaction

Stimulus → receptor cells → Sensory neurone → spinal cord → motor neurone → effector →response

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4
Q

What does a motor neurone do

A

Carry electrical impulses from the cns to the effectors

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5
Q

What do sensory neurones do

A

Carry electrical impulses from receptor cells to cns

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6
Q

How are nerve impulses moved across neurones

A

The synaptic cleff is the area between two neurons.

A nerve impulse pushes the Neurotransmitters in vesicles to the edge of the presynaptic neurone

It diffuses across the postsynaptic neurone where it binds to the receptors (lock and key hypothesis) which creates a new nerve impulse

An example of a neurotransmitter used is adenosine

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7
Q

What are the main parts of an eye and what are there functions

A

Suspensory ligament - alters the shape of the lense (so does ciliary muscle)
Retina - contains photoreceptors (rods and cones)
Optic nerve - carries impulses to the brain
Lense - refracts and focuses light onto the retina (so does the cornea)
Pupil - allows light into the eye
Iris - controls the size of the pupil

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8
Q

What two muscles is the iris made of, and what are their purposes

A

The circular (inside) and radial (outside) muscles

When the circular muscle contracts the radial relaxes, letting less light into the eye
(Constriction)

When the radial contracts the circular relaxes, letting more light into the eye
(Dilation)

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9
Q

How do we focus on close objects.

A

The lens must be thicker to refract the light more.

The ciliary muscle contracts causing the suspensory ligament to slacken (reducing tension)
This makes the lens bulge and be more convex

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10
Q

How do we focus on far images

A

The lens needs to refract light less

The ciliary muscle relaxes, making the suspensory ligament taught, increasing tension.
The greater tension makes the lens stretch becoming less convex

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11
Q

What is the process of focusing on different distanced objects called

A

Accomodation

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12
Q

What is hyperopia and why does it occur.

A

Long sightedness (cant focus on close objects)

It occurs when the focal point is too far behind the eye or the eyeball is too short (or lens is less convex)

A convex (converging) lens is used to fix it (light refracts more)

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13
Q

What is myopia and why does it occur

A

Short - sightedness (cant focus far objects)

Focal point is in front of the retinas
Eyeball is too long / lens refracts too much

This is fixed using a concave lens which refracts the light outwards

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14
Q

What are rods and cones

A

Rods - respond to light

Cones - respond to colours

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15
Q

What is colour blindness

A

The inability to see certain colours due to a lack of cones

It is sex linked and more common in men

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16
Q

What are the parts of the brain?

A

Cerebrum - controls complex behaviour ( learning / voluntary movement / conscious thought(

Cerebellum - controls posture balance and involuntary movement

Hypothalamus - thermal / water (osmoregulation) regulation

Pituitary gland - controls hormones / stores and releases hormones

Medulla - controls automatic reactions like heart rate

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17
Q

What are hormones?

A

Chemical messengers that cause a response in specific target hormones

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18
Q

What is the endocrine system

A

All the endocrine glands and the hormones they produce.

An endocrine gland is a gland which secretes hormones

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19
Q

What is a target organ

A

Organ a hormone has effect on

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20
Q

How are hormones carried

A

In the blood stream in plasma

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21
Q

How are the endocrine system and the nervous system related

A

They both send messages around the body for a response.

Together they control and coordinate body processes

They provide information about changes in your environment

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22
Q

What are target cells and what do hormones do to them

A

Target cells are cells which a hormone is able to bind to.

Hormones diffuse out of the blood and bind to receptors (with a complimentary active site) found on the cells membrane or cytoplasm

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23
Q

Differences between the nervous system and endocrine system

A

Nerves - travel fast through electrical impulses, and act for a short time over a small area

Hormones - travel slower through the blood, and act for a longer time for a larger ara

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24
Q

Name 3 hormones, what they do, and the gland they are released from.

A

Testosterone - Released from the testes, promotes growth of secondary male characteristics

Thyroxine - Released from the thyroid (found in your throat) gland and controls metabolic rate

Adrenaline - released from your adrenal gland (above the kidneys) and is responsible for your fight or flight response

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25
Q

What is negative feedback

A

A process in homeostasis:

A change away from the normal value is detected and your body works to return that value to normal through the use of effectors

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26
Q

What is homeostasis

A

A process which:

Maintains internal body conditions within a narrow range

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27
Q

What does adrenaline do

A

When you feel threatened or scared the brain (specifically your hypothalamus) signals the adrenal glands to secrete adrenaline

This results in:
Higher respiration rate, more oxygen is needed to produce more ATP
Increasing heart rate (to transport the oxygen elsewhere)
Blood diversion from non essential organs like skin or your digestive system to the blood.

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28
Q

What is TRH and what releases it

A

TRH - thyroid releasing hormone (released by the hypothalamus)
It travels through the blood stream and binds to the pituitary gland

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29
Q

What is TSH and what gland is it secreted by

A

TSH - thyroid stimulating hormone (released by the anterior pituitary gland)
Binds to the thyroid causing thyroxine to be produced

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30
Q

How is negative feedback used to keep thyroxine levels stable.

A

-The hypothalamus detects a change in thyroxine levels
-It releases TRH which is transported through the blood to the anterior pituitary gland
-once it binds to that TSH is released which then travels through the blood to the thyroid gland
-TSh binds to specific shaped receptors on the thyroid gland
-thyroxine is then produced

-the hypothalamus detects this and stops producing TRH
-the thyroxine increase inhibits the production of TSH

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31
Q

What is Goitre

A

A condition which causes a swollen thyroid gland due to an iodine deficiency

Iodine is required for the production of thyroxine, so people with goitre will have a lower metabolism

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32
Q

What is FSH

A

Follicle stimulating hormone - is secreted by the pituitary gland and travels to the ovaries where it causes an egg to mature

It also stimulates the ovaries to produce Oestrogen

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33
Q

What is LH

A

Luteinising Hormone - triggers ovulation (also comes from the pituitary gland)

Causes empty egg follicles to develop into the corpus luteum - so progesterone is released

Inhibits FSH and oestrogen

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34
Q

What is Oestrogen

A

Oestrogen is a hormone secreted by the ovaries and causes the uterus lining to build up

It inhibits FSH from being produced. And it stimulates the pituitary gland to release LH

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35
Q

What is progesterone

A

Progesterone is a hormone secreted by the corpus luteum in the ovaries. It maintains the uterus lining

This hormone remains high during pregnancy.

It inhibits FSH and LH

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36
Q

What is the menstraul cycle

A

The 28 day cycle where a woman’s body is prepared for pregnancy

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37
Q

What is the menstrual cycle

A

The 28 day cycle where a woman’s body is prepared for pregnancy

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38
Q

What happens during day 0-5 of the menstrual cycle

A

Menstruation (a period) will occur.

The uterus lining breaks down

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39
Q

What happens during day 5-13 of the menstrual cycle

A

The uterus lining thickens (high amounts of oestrogen)

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40
Q

What happens during day 14 of the menstrual cycle

A

Ovulation - an egg is released by the ovaries, and empty egg follicles break down into the corpus luteum

(High amounts of LH around / before day 14)

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41
Q

What happens during day 14-28 of the menstrual cycle

A

The uterus lining stays the same
(High amounts of progesterone)

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42
Q

What happens if an egg isnt fertilised by day 28

A

The uterus lining (endometrium) breaks down

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43
Q

What is a haploid cell, and what is a diploid cell

A

Haploid cell contains one set chromosomes (sperm or egg)

A diploid cell contains two sets chromosomes (e.g a Zygote)

44
Q

What is contraception

A

Methods used to prevent pregnancy split into hormonal and non hormonal.

Currently hormonal systems only effect the female reproductive system

45
Q

What are the non hormonal methods of contraception and how do they work.

A

Condoms - placed over the penis or inside the vagina, prevents sperm from entering the vagina. They are a one time use and prevent STIs

Diaphragm or cervical cap - inserted into the cervix to prevent sperm entering the uterus. Removed 6+ hours after sexual intercourse ( only effective if paired with spermicide)

IUD - Inserted into the uterus and releases copper which prevents sperm surviving in fallopian tubes or the cervix. Can also prevent ovum implantation
(Effective for 5-10 years)

46
Q

How effective is each method of contraception

A

Male condom 98%
Female condom 95%
Diaphragm and cap 92-96%
(Assuming they are used correctly)

The other methods are over 99%

47
Q

Why are some people infertile.

A

Too old
Blocked sperm ducts
Not enough sperm produced
A lack of mature eggs
A failure from the ovaries to release an egg

48
Q

How does fertility treatment work.

A

FSH can be used as a drug to try and stimulate eggs to mature in the ovaries.

49
Q

What is IVF and how does it work.

A

In vitro fertilisation is the process of binding a sperm cell and an egg cell outside of the female reproductive system.

Eggs are taken from the female using a vaginal ultrasound + anesthetic
Sperm capacitation must occur (through ejaculation)
Prepare the semen and eggs and then IVF can occur in 2 ways

Conventional - Egg is surrounded by sperm cells and one binds with the egg

Intra-cytoplasmic sperm injection (ICSI) - one specific sperm is inserted into the egg

Once this is done the zygote (at its current stage a blastocyst) will be incubated for around 5 days where it should have grown to 32 cells.
Multiple embryos are then transferred back into the woman for a higher chance of success

50
Q

What is tropism

A

Growth or movement in one direction due to stimulus

51
Q

What is phototropism and how does it work

A

Negative (nothing happens)+ positive

Plant grows toward the light

Auxin in the shoot tip diffuses down and away from the light causing a faster rate of cell elongation on the side of most auxin. This makes the plant grow to the light

52
Q

What is gravitropism and how does ot work

A

Gravitropism is the plants roots moving with gravity

Auxins diffuse down the root.
Cell elongation occurs on the side with the least auxin

53
Q

What are the three main plant hormones and what do they do

A

Auxin - promotes cell elingation and fruit development
Ethene - ripens fruit by converting starch in glucose
Gibberellins - promotes cell elongation and breaks seed dormancy

54
Q

Give three practical uses of plant hormones

A

Plants can be gassed with ethene a day before they are taken to the shops ensuring they are as ripe as possible

Seedless fruit can be made by adding auxin to them as it can cause fruit development even without fertilisation
(Parthenocarpy)

Weed killer is made using auxins. As broader leaves have a greater diffusion area they will gain more auxins, causing them to grow uncontrollably and die

Gibberellins can be used to make seeds germinate

55
Q

Where can your thermoreceptors and osmoreceptors be found

A

In your brain - in the hypothalamus
They can also be found in the skin to detect external temperatures

56
Q

How does your body detect an increase or decrease in your body temperature.

A

Your thermoreceptors will detect a change in the temperature of your blood away from 37°C

57
Q

What happens when your body gets too cold.

A

Shivering (thermogenics) - muscles contract and relax - aerobic respiration is exothermic so energy is released heating you up + break down of atp is exothermic releasing even more energy

Hairs raising - Your erector muscles control your body hairs and when they contract your body hairs rise. When they rise air is trapped, the air will warm up as its close to your skin and cant rise to escape so heat loss by convection is released

Vasoconstriction - Arterioles constrict which reduces blood flow to the capillaries at the skin so less heat is lost by radiation

58
Q

What happens when you are too hot

A

Vasodilation - Arterioles widen and blood rushes to capillaries near your skin. Heat lost by radiation increases - this is what causes your skin to turn red

Sweating - sweat produced by sweat gland (exocrine gland). When it evaporates thermal energy is transferred into the environment
Water is also held together by hydrogen bonds they absorb thermal energy to break and then the water can evaporate (endothermic reaction)

Erector muscles relax

59
Q

What is glucose homeostasis

A

Process to keep glucose concentration levels stable

60
Q

How are glucose levels kept stable

A

When you eat your blood glucose level increases
The pancreas detects a change
The pancreas releases insulin
This travels through the blood and binds to specific target receptors in muscles and the liver (target organ)
This causes glucose to be converted to glycogen
Then your blood sugar level decreases

61
Q

Whats the average blood glucose concentration

A

90mg / 100ml of blood

62
Q

How is glycogen converted back into glucose

A

Pancreas detects decrease of blood glucose concentration using receptors
Glucagon is secreted into the blood stream . - by the pancreas
Glucagon binds to target receptors in the muscles or liver
Glucagon causes glycogen to break down back into the blood

This makes the blood glucose concentration increase

63
Q

What is type 1 diabetes

A

Your body is unable to produce insulin as beta cells (insulin producing cells) in the pancreas are destroyed by your immune system.

This can be controlled through insulin injections

64
Q

What is type 2 diabetes

A

Often occurs due to obesity
Body doesn’t produce enough insulin
They could also have insulin resistance

Insulin resistance happens when people produce too much insulin and they become insulin deficient

This can also be controlled by insulin injections

65
Q

What is Hypoglycemia and hyperglycemia

A

1) Low glucose levels in the blood
2) High glucose levels in the blood

66
Q

What are the two main functions of the kidney

A

Excretion - removal of metabolic waste (water h2o or urea)
Osmoregulation - maintains water potential in the blood

67
Q

How is urea produced

A

Urea is produced by the breakdown of amino acids as when they break down ammonia is released. This is dangerous so it combines with carbon dioxide to form urea

68
Q

What does the term renal refer to.

A

Renal refers to the kidneys

69
Q

What is the structure of a sensory neuron

A

The dendrites are connected to a dendron.

The dendron passes through the cell body, then through the axon to the axon terminals.

The axon / denron is surround by the mylin sheath

70
Q

What do dendrites do

A

Receive a neuro-transmitter which starts a nerve impulse

71
Q

What does the axon terminal do

A

It releases neuro-transmitters which bind to receptors on the dendrites

72
Q

What does the dendron / axon do

A

They join the dendrites and axon terminals together allowing electrical impulses to pass.

The impulse travels through these

73
Q

What does the mylin sheath do

A

Protects / insulates the neuron the
Speeds up the transport of nerve impulses
Maintains the impulse strength

74
Q

What days are the best days for fertilisation

A

The days before ovulation, days 12-14

75
Q

What is metabolic waste

A

The products that cannot be used up

These waste products are as a result of metabolic reactions

76
Q

What is the structure of the kidney

A

He kidney is made up of nephrons which all connect to each other through collecting ducts

Your kidney is made of a
capsule - outer membrane of the kidney (maintains the kidneys shape)
Cortex - outer part of the kidney
Medulla - inner part of the kidney

The kidney is also connected to the ureter which takes urine to the bladder

Renal artery / vein

77
Q

How is the nephron structured

A

The glomerulus is located inside the bowman capsule

Glomerulus - complex web of capillaries and it filters the blood
Bowmans capsule - The filtrate travels through here and into the proximal convoluted tubule

From the proximal convoluted tubule it travels to the loops of henlé and then up to the distal convoluted tubule

It then enters the collecting duct and leaves the kidney

78
Q

What is each process that occurd in nephron and where they do they occur

A

Ultrafiltration - in the glomerolous, ions, amino acids, glucose, salt and water are absorbed into the bowmans capsule

Selective reabsorption - in the proximal convoluted tubule (some ions some water, all sugars and amino acids are abslrbed back into the blood stream)

Reabsorbtion - in the collecting duct. some water is reabsorbed / most salts/ions are reabsorbed - the filtrate remains as ions water and urea

79
Q

What is adh / what does it do and what releases it

A

Anti - diuretic hormone released by the pituitary glands

It causes the collecting duct to be more permeable to water so more is absorbed

80
Q

What is the structure of a motor neuron

A

It only has an axon surrounded by a mylin sheath

The cell body is found by the dendrites
It has dendrites and axon terminals

81
Q

What is the structure of a relay neuron

A

It has dendrites and axons connected to a cell body

82
Q

What happens when you have a low water potential in your blood

(Kidneys)

A

Your pituitary gland will release more adh

This means the collecting duct will be more permeable to water, so more water is released back into the blood

Results in more concentrated urine

83
Q

What is the pns

A

All neurons outside the cns

(Peripheral nervous system)

84
Q

What happens when the pns is damaged (symptoms)

A

Inability to detect pain
Numbness
Lack of coordination

85
Q

What happens when the cns is damaged

A

Loss of control of body systems
Partial or complete paralysis
Memory loss or processing difficulties

86
Q

How can brain function be investigated

A

Through scans
Mri
Pet scans
Ct scand
Fmri scans

87
Q

How does each scan work and what are its dangers

A

MRI - magnetic fields + radio waves to map inages of the brain (whole body goes in the machine, so pacemakers and artificial joints can be damaged) It looks at structure and gives high res images

PET - uses radiotracers (e.g radioactive glucose), releases positrons that show function. This produces gama rays which are dangerous

CT - x ray images of the brain - low resolution image that looks at structure

FMRI - uses responses of oxygenated and deoxygenated blood to show brain response. Has the same issues as mri scans

X-rays - use ionising radiation which in large / frequent amounts can cause mutation or damage to DNA

88
Q

Advantages and disadvantages of studying the brain

A

Advantages:
Alows for a greater understanding of how the brain works
Can help decide treatment for certain injuries

Disadvantages:
ethical issues → (can ppl w brain damage consent)
Its fragile → damage to tissue can remove brain functions
Risk of damage from radiation.
May be hard to find volunteers to study
People with brain damage cant give fully informed consent
Difficult to pinpoint a function

89
Q

What does a convex lens do

A

Refracts light inward to a point
(Thick lens)

90
Q

What does a concave lens do

A

Disperses light outwards
(Thin one)

91
Q

What happens when the iris constricts

A

The circular muscle (smaller inside muscle) contracts and the radial (larger outside muscle) relaxes.

This makes the pupils diametermaller and lets less light in

92
Q

What happens when the iris dilates

A

The circular muscle (smaller inside muscle) relaxes and the radial (larger outside muscle) contracts.

This increases the pupils diameter, letting in more light

93
Q

Why does caffeine stop you from being tired

A

Adenosine ( a neuro transmitter) binds to the postsynaptic neuron.
Caffeine has the same shape and can bind instead, which means the feeling of drowsiness will be produced less

94
Q

Where are most motor neurons found

A

By the brain and spinal chord

95
Q

What is a synapse

A

A junction between two neurons

96
Q

What is FSH + what does it do

A

Follicle stimulating hormone
Causes egg to mature in the ovaries
Stimulates production of oestrogen

Secreatrd by the pituitary gland

97
Q

What is oestrogen + whats it do

A

Causes the lining of the uterus to build up
Secreted by the ovaries
Inhibits FSH
Stimulates release of LH

98
Q

What is LH + what it do

A

Luteinising hormone.
When this hormone peaks ovulation occurs.
Causes empty follicles to break down into the corpus leuteum

99
Q

What is progesterone + whats it do

A

Maintains the uterus lining
Released by the corpus luteum

Inhibits LH, Oestrogen and FSH

100
Q

What does the progesterone pill do

A

Thickens cervical mucus stopping sperm from reaching an ovum.
Thins the uterus lining, preventing implantation.
It can also prevent ovulation.
It must be taken around the same time every day

101
Q

What does the combined pill do

A

(Oestrogen and progesteron)
Prevents ovulation,
thickens cervical mucus preventing the sperm from reaching an ovum.
Prevents fertilised eggs implanting into the uterus.
Taken for 21 days of the menstrual cycle

102
Q

What does an IUS do

A

An intrauterine system

Thickens cervical mucus stopping sperm from reaching an ovum.
Thins the uterus lining, preventing implantation.
It can also prevent ovulation.
It must be taken around the same time every day

103
Q

What are two common methods of excretion

A

Breathing out and through the kidneys (urination)

104
Q

Where is glycogen stored

A

In the liver or the muscles

105
Q

Issues of using case studies to study the brain

A

May not be able to consent → finding volunteers is hard

Very specific study

(A) Biology (8 decks)

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