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(B - GCSE) Biology > B3 > Flashcards

B3 Flashcards

(105 cards)

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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
What is negative feedback
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
26
What is homeostasis
A process which: Maintains internal body conditions within a narrow range
27
What does adrenaline do
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.
28
What is TRH and what releases it
TRH - thyroid releasing hormone (released by the hypothalamus) It travels through the blood stream and binds to the pituitary gland
29
What is TSH and what gland is it secreted by
TSH - thyroid stimulating hormone (released by the anterior pituitary gland) Binds to the thyroid causing thyroxine to be produced
30
How is negative feedback used to keep thyroxine levels stable.
-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
31
What is Goitre
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
32
What is FSH
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
33
What is LH
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
34
What is Oestrogen
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
35
What is progesterone
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
36
What is the menstraul cycle
The 28 day cycle where a woman's body is prepared for pregnancy
37
What is the menstrual cycle
The 28 day cycle where a woman's body is prepared for pregnancy
38
What happens during day 0-5 of the menstrual cycle
Menstruation (a period) will occur. The uterus lining breaks down
39
What happens during day 5-13 of the menstrual cycle
The uterus lining thickens (high amounts of oestrogen)
40
What happens during day 14 of the menstrual cycle
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)
41
What happens during day 14-28 of the menstrual cycle
The uterus lining stays the same (High amounts of progesterone)
42
What happens if an egg isnt fertilised by day 28
The uterus lining (endometrium) breaks down
43
What is a haploid cell, and what is a diploid cell
Haploid cell contains one set chromosomes (sperm or egg) A diploid cell contains two sets chromosomes (e.g a Zygote)
44
What is contraception
Methods used to prevent pregnancy split into hormonal and non hormonal. Currently hormonal systems only effect the female reproductive system
45
What are the non hormonal methods of contraception and how do they work.
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
How effective is each method of contraception
Male condom 98% Female condom 95% Diaphragm and cap 92-96% (Assuming they are used correctly) The other methods are over 99%
47
Why are some people infertile.
Too old Blocked sperm ducts Not enough sperm produced A lack of mature eggs A failure from the ovaries to release an egg
48
How does fertility treatment work.
FSH can be used as a drug to try and stimulate eggs to mature in the ovaries.
49
What is IVF and how does it work.
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
What is tropism
Growth or movement in one direction due to stimulus
51
What is phototropism and how does it work
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
What is gravitropism and how does ot work
Gravitropism is the plants roots moving with gravity Auxins diffuse down the root. Cell elongation occurs on the side with the least auxin
53
What are the three main plant hormones and what do they do
Auxin - promotes cell elingation and fruit development Ethene - ripens fruit by converting starch in glucose Gibberellins - promotes cell elongation and breaks seed dormancy
54
Give three practical uses of plant hormones
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
Where can your thermoreceptors and osmoreceptors be found
In your brain - in the hypothalamus They can also be found in the skin to detect external temperatures
56
How does your body detect an increase or decrease in your body temperature.
Your thermoreceptors will detect a change in the temperature of your blood away from 37°C
57
What happens when your body gets too cold.
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
What happens when you are too hot
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
What is glucose homeostasis
Process to keep glucose concentration levels stable
60
How are glucose levels kept stable
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
Whats the average blood glucose concentration
90mg / 100ml of blood
62
How is glycogen converted back into glucose
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
What is type 1 diabetes
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
What is type 2 diabetes
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
What is Hypoglycemia and hyperglycemia
1) Low glucose levels in the blood 2) High glucose levels in the blood
66
What are the two main functions of the kidney
Excretion - removal of metabolic waste (water h2o or urea) Osmoregulation - maintains water potential in the blood
67
How is urea produced
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
What does the term renal refer to.
Renal refers to the kidneys
69
What is the structure of a sensory neuron
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
What do dendrites do
Receive a neuro-transmitter which starts a nerve impulse
71
What does the axon terminal do
It releases neuro-transmitters which bind to receptors on the dendrites
72
What does the dendron / axon do
They join the dendrites and axon terminals together allowing electrical impulses to pass. The impulse travels through these
73
What does the mylin sheath do
Protects / insulates the neuron the Speeds up the transport of nerve impulses Maintains the impulse strength
74
What days are the best days for fertilisation
The days before ovulation, days 12-14
75
What is metabolic waste
The products that cannot be used up These waste products are as a result of metabolic reactions
76
What is the structure of the kidney
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
How is the nephron structured
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
What is each process that occurd in nephron and where they do they occur
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
What is adh / what does it do and what releases it
Anti - diuretic hormone released by the pituitary glands It causes the collecting duct to be more permeable to water so more is absorbed
80
What is the structure of a motor neuron
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
What is the structure of a relay neuron
It has dendrites and axons connected to a cell body
82
What happens when you have a low water potential in your blood (Kidneys)
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
What is the pns
All neurons outside the cns (Peripheral nervous system)
84
What happens when the pns is damaged (symptoms)
Inability to detect pain Numbness Lack of coordination
85
What happens when the cns is damaged
Loss of control of body systems Partial or complete paralysis Memory loss or processing difficulties
86
How can brain function be investigated
Through scans Mri Pet scans Ct scand Fmri scans
87
How does each scan work and what are its dangers
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
Advantages and disadvantages of studying the brain
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
What does a convex lens do
Refracts light inward to a point (Thick lens)
90
What does a concave lens do
Disperses light outwards (Thin one)
91
What happens when the iris constricts
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
What happens when the iris dilates
The circular muscle (smaller inside muscle) relaxes and the radial (larger outside muscle) contracts. This increases the pupils diameter, letting in more light
93
Why does caffeine stop you from being tired
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
Where are most motor neurons found
By the brain and spinal chord
95
What is a synapse
A junction between two neurons
96
What is FSH + what does it do
Follicle stimulating hormone Causes egg to mature in the ovaries Stimulates production of oestrogen Secreatrd by the pituitary gland
97
What is oestrogen + whats it do
Causes the lining of the uterus to build up Secreted by the ovaries Inhibits FSH Stimulates release of LH
98
What is LH + what it do
Luteinising hormone. When this hormone peaks ovulation occurs. Causes empty follicles to break down into the corpus leuteum
99
What is progesterone + whats it do
Maintains the uterus lining Released by the corpus luteum Inhibits LH, Oestrogen and FSH
100
What does the progesterone pill do
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
What does the combined pill do
(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
What does an IUS do
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
What are two common methods of excretion
Breathing out and through the kidneys (urination)
104
Where is glycogen stored
In the liver or the muscles
105
Issues of using case studies to study the brain
May not be able to consent → finding volunteers is hard Very specific study

(B - GCSE) Biology (8 decks)

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