Multiple Topic key Facts

Question 1

Role of receptors and effectors

Answer 1

Communicating information form one part of the body to another part, makes sure activities of organs are co ordinated well with the rest of the body

Question 2

How does hormonal system work

Answer 2

Cells release chemicals(hormones) into the blood and they travel to the target area where they send signals to distant cells, receptors on cells allow them to detect the chemical signals

Question 3

How do the different nuerons vary in structure

Answer 3

Sensory: short dendrites attached to receptor, long dendron, short axon
Motor: many short dendrites, long axon that carries impulse to effector cell
Relay: many short dendrites, one axon that carries impulse to motor neurone

Question 4

What is the role of sensory receptors

Answer 4

They act as a transducer (Turing any type of energy into electrical energy)

Question 5

How is the resting potential formed

Answer 5

Due to the outside of the receptor being negatively charged and the inside being positively charged (this creates voltage across membrane. This is called a potential difference and when at rest it’s the resting potential (generated by ion pumps and channels) 70MV

Question 6

What is generator potential

Answer 6

When a cell membrane gets excited it becomes more permeable meaning more ions flow through it altering the potential difference. Change in potential due to this stimulus is the generator potential

Question 7

When is an action potential triggered

Answer 7

It will only trigger if there is a large enough generator potential that surpasses the threshold level at 60MV

Question 8

How is resting potential maintained

Answer 8

It’s is maintained by the sodium potassium pumps using active transport to move 3 sodium ions out of the neurone for every 2 potassium ions move in (process requires ATP)

The potassium ion channels allow facilitated diffusion of K+ out of the nuerons down the concentration gradient

Question 9

The full action potential

Answer 9

Stimulus: Neurone cell membrane excites meaning it is more permeable so the sodium ion channels open. This causes the sodium ions outside the cell to diffuse into the neurone down the electrochemical gradient which makes inside of cell less negative

Depolarisation: if potential difference reaches -55mv , voltage gated sodium ion channels open meaning neurone becomes more positive (positive feedback)

Repolarsation: at potential difference of +30mv the sodium ion channels close and voltage gated potassium ion channels open, this means potassium ions diffuse out which will start to make the membrane go back to its resting potential.

Hyperpolarasation: potassium ion channels are slow to close so it does go below -70MV for a short time (due to many potasuim ion diffusing out)

Returns to resting potential

Question 10

Role of refractory period

Answer 10

Acts as a time delay and stops multiple action potentials happing at same time and makes sure the action potentials are unidirectional

Question 11

What is an action potential response known as

Answer 11

All or nothing response

Question 12

Affect of the size of the stimulus on action potentail

Answer 12

A bigger stimulus causes more frequent action potentials whilst a small stimulus will cause less frequent action potentials

Question 13

Structure of myelinated neurones

Answer 13

They will have a myelin sheath which is an electrical insulator. The myelin sheath is made of Schwann cells and has tiny patches of non myelinated membrane called nodes of ranvier ( sodium ion channels are concentrated in this area)

Question 14

Saltatory conduction

Answer 14

In myelinated neurones depolarisation only happens at nodes of ranvier (sodium ions can get through at this point) the neurones cytoplasm conducts enough electrical charge to depolarise the next node so impulse jumps node to node. Very fast

Question 15

Non myelinated conduction

Answer 15

Impulse travels as a wave along the whole length of the axon, this is slower that the saltatory conduction

Question 16

Effect of axon diameter

Answer 16

Action potentials are conducted quicker in large diameter axons because there is less resistance to the flow of ions from the cytoplasm. Less resistance means depolarisation reaches other parts faster

Question 17

Affects of temperate and neurones

Answer 17

With an increase in temp the speed of conduction will increase because the ions will diffuse faster. Only increase up to about 40 before proteins start to denature

Question 18

Synaptic transmission

Answer 18

• action potential arrives at synaptic knob of the presynaptic neurone. The action potentials makes the voltage gated calcium ions open allowing calcium to diffuse into synaptic knob
• influx of calcium ions cause the vesicles with Acetylcholine (the neurotransmitter) to fuse with the presynaptic membrane and release acetylcholine into synaptic cleft by exocytosis.
• the acetylcholine diffuses across synaptic cleft onto cholineric receptors on the post synaptic membrane. This causes sodium ion channels to open which will cause depolarisation and a action potential will be generated if it reaches the threshold
• the neurotransmitter is then removed from the cleft by a enzyme and the pre synaptic neurone takes the products from this.

Question 19

Excitatory synapses

Answer 19

They will depolarise the presynaptic neurone making it fire an action potentail

Question 20

Inhibitory synapse

Answer 20

Will hyperpolarise the presynaptic Neurone making it more negative so an action potential can’t be generated

Question 21

Synaptic divergence and convergence

Answer 21

Divergence is when one neurone connects to many neurones (information is dispersed)
Convergence is when many neurones connect to one neurone (information is amplified)

Question 22

Summation

Answer 22

Is when multiple Neurones release there neurotransmitters to cause an action potential in a post synaptic neurone ( needs multiple as one can’t release enough neurotransmitters by itself)

Question 23

Spatial summation

Answer 23

When 2 or more presynaptic neurones converge and release neurotransmitters at the same time onto the same post synaptic neurone to trigger an action potential. However if the other some of the neurotransmitters are inhibitory there may still be no action potentail generated.

Question 24

Temporal summation

Answer 24

When a single presynaptic neurone has a high stimulus meaning it will release many neurotransmitters in waves, so the action potential might not happen until the third wave of neurotransmitters is released

Question 25

What is a hormonal system

Answer 25

Send information as chemical signals and it is made up endocrine glands and hormones. Hormones are secreted when a endocrine gland is stimulated by another hormone or a change in concentration of a specific substance

Question 26

Hormonal communication

Answer 26

Hormones travel round the body via the blood and diffuse out of the blood once they reach the target cells with complimentary receptors. Tissue that contains target cells is called target tissue

Question 27

Action of hormones

Answer 27

Hormones (first messenger) will bind to complementary receptors and it will activate an enzyme to produce a molecule inside the cell called the signalling molecule (second messenger) . This molecule signals to other parts of the cell to change how it is working

Question 28

Role of adrenaline

Answer 28

Adrenaline is a hormone made in your adrenal gland and it is secreted when you have low glucose concentrations or (stressed,exercising). Adrenaline gets your body ready for action by breaking down glycogen into glucose by glycogenolysis

For adrenaline the enzyme it activivates when it binds to a receptor is adenylyl cyclase which will catalyse the production of the molecule cAMP.

Question 29

Adrenal glands structure

Answer 29

Endocrine gland above your kidney

Outer part is called the cortex and the inside part is called the medulla

Question 30

What does the cortex secrete and what impact does it cause

Answer 30

Secretes steroid hormones

• stimulates break down of proteins and fats into glucose (so muscles can respond)
• increases blood volume and pressure by increasing sodium ion and water uptake in the kidneys
• surpresses immune system

Question 31

The medulla and what it secretes and what impact it has

Answer 31

Secretes adrenaline that will increase your breathing rate and heart rate and constricts some blood vessels so blood is directed to muscles and brains

Question 32

What is negative feedback

Answer 32

Negative feedback is mechanism that will return a level of something back to normal despite a stimulus (when effectors respond)

Question 33

Positive feedback

Answer 33

When effectors respond to further increase the level away from the normal level

Question 34

How do ectotherms controls body temp

Answer 34

Ectotherms can’t control body temp internally so they control temprature with different behaviours eg: when they are to hot they will sit in the shade and cool off ( they are more active at high temperatures than low temperature because more metabolic process are happening)

Question 35

How do endothermic control body temperature

Answer 35

Controlled by homeostasis meaning we have a more constant metabolic rate

Question 36

Mechanisms to decrease body temp

Answer 36

• sweating
• hairs lie flat
• vasodilation: artérioles near surface of the skin dilate

Question 37

Mechanism to increase body temp

Answer 37

Shivering ( increases temp due to more respiration)
Hormones ( which will increase metabolic rates)
Hair stand up
Less sweat

Question 38

What controls body temp

Answer 38

Body temp is maintained by the hypothalamus in the brain (which recieves its information from thermo receptors which are sent by the sensory neurone to the hypothalamus)

Question 39

Hormonal control of blood glucose concentrations

Answer 39

When levels of blood glucose are to high the pancreas will secrete insulin from the beta cells which will travel in the blood to the liver or muscles cells. When the insulin reaches its target cell it will bind to the complentary receptor and make the membrane more permeable to glucose whilst it also activates an enzyme which will convert glucose into glycogen for storage (glycogenisis

If blood glucose levels are too low the pancreas will secrete the hormone glucagon from the alpha cells which will travel in the blood to the liver or muscle cells once it reaches the target cells it will bind to the receptor and activate the enzyme that will break down glycogen into glucose (glycogenolysis), also glucagon promotes formation of glucose from glycerol and amino acids (glyconeogenesis)

Question 40

Secretion of insulin

Answer 40

• When blood glucose conc is high glucose goes into beta cells by facilités diffusion
• Which will cause and increase in respiration and ATP production
• Rise in ATP cause potassium channels to close so K+ can’t get out making the cell more positively charged
• this makes the plasma membrane depolarised
• This triggers calcium ion channels to open so calcium ions diffuse in
• This makes the vesicles fuse with the plasma membrane via exocytosis releasing the insulin

Question 41

Type 1 diabetes and how to treat it

Answer 41

Type 1 diabetes is an auto immune disease that attacks and destroys your beta cells in your islet of langerhan. Meaning they can’t produce insulin

Treated by having regular insulin injections after meals or can have a isclet cell transplantation

Question 42

Type 2 diabetes

Answer 42

Happens when beta cells don’t produce enough or your body doesn’t respond to insulin properly because the insulin receptors on the target cell membranes don’t work and don’t take up enough glucose

Treatment can be just have a more healthy lifestyle or lose weight

Question 43

Benefits from producing insulin from GM bacteria

Answer 43

• cheaper
• large quantities can be produced
• makes human insulin instead of pig insulin which could trigger an allergic response
• better ethically don’t need to kill animals

Question 44

What is the cytoskeleton

Answer 44

Cytoskeleton is a network of protein threads (microfibrils and microtubeles) running through the cytoplasm holding the organelles in place, provides strength and maintains cell shape,transport materials and organelles within cell, can also help cell move.

Question 45

Transmission electron microscope

Answer 45

Focus beam of electrons which goes through the specimen producing a 2D image, dense parts appear darker as absorbed more electrons. Specimens need to be thinly sliced and dead

Question 46

Scanning electron microscope

Answer 46

Beam of electrons across the surface of the specimen and gives a 3D image that is of a lower resolution than the TEM