Posters

Question 1

High blood glucose

Answer 1

Beta cells in pancreas
Release insulin into blood
Target cells are liver cells- binds to specific complementary receptors on liver cell membrane
Causes:
More glucose channels inserted… glucose moves from blood to liver via facilitated diffusion
Activation of enzymes causing glycogenesis- glucose is soluble and would affect water potential if not
Excess glucose converted to fats and proteins
Rate of respiration increases

Question 2

Low blood glucose

Answer 2

Alpha cells detect low glucose
Release glucagon
Target cells are liver cells. Glucagon binds to complementary receptors on liver cell membrane
Binding causes second messenger model:
Activation of enzyme- ardenylase cyclase 
Converts ATP to cyclic AMP
Camp is second messenger
Camp activates protein kinase A
Protein kinase A causes glycogenolysis 
Glucose leaves the liver and goes into blood by glucose channels
Activates enzymes for gluconeogenesis 
Rate of respiration reduced

Question 3

Adrenaline

Answer 3

Secreted from adrenal glands
Secreted at low blood glucose concentration, when you’re stressed or exercising
Activates glycogenolysis(same as glucagon)
Activates glucagon/inhibits insulin secretion
Have same effect so is amplified

Question 4

Advantages of second messenger model

Answer 4

Conversion of ATP to cAMP by adenylate Cyclase is carried out many times so lots of cAMP produced
Each cAMP activates many protein kinase enzymes
Each enzyme causes glycogenolysis
So faster release of glucose

Question 5

Type 1 diabetes

Answer 5

Caused by immune system attacking and damaging beta cells in pancreas so CANT PRODUCE insulin
Controlled by regular injections

Question 6

Type 2 diabetes

Answer 6

Body cells don’t respond to insulin 
Receptors lose sensitivity to insulin 
Controlled by diet/starch over sugars
Losing weight and exercise
Glucose lowering tablets/insulin injections 

Symptoms
Kidney failiure
Visual impairment
Glucose in urine

Question 7

What is metastasis

Answer 7

Tumour that has spread

The blood or lymphatic system so can spread and cause secondary tumours (difficult to treat)

Question 8

Causes of cancer

Answer 8

Genetics
Environmental factors
Lifestyle smoking/saturated fat
Age- more mutations so more likely to have mutations disturbing cell cycle

Question 9

Tumour suppressor genes

Answer 9

Slow cell division by producing protein that slow cell division/ causes apoptosis

Mutated gene. Prevents formation of functional protein. Mitosis not inhibited so cell division increased

Question 10

Proto oncogene

Answer 10

Stimulates cell division by producing proteins that make cells divide- codes for proteins that act as growth factors- only expressed when growth is needed

Mutation stimulates uncontrolled transcription and translation which causes over production of growth factors- increased uncontrolled mitosis

Question 11

Methylation

Answer 11

Normal methylation- transcription is inhibited
Increased methylation makes DNA more coiled- dna helicase and polymerase can’t interact with gene
Hypermethylation of tsg causes uncontrolled cell division
Hypo methylation of proto oncogenes increases cell division

Question 12

Oestrogen and breast cancer

Answer 12

Oestrogen can stimulate certain breast cells to divide and increase in cell division= increased chance of mutation
High levels of oestrogen cause cancer cells to divide even faster
Oestrogen can increase chances of mutations/ increased chance of breast cancer

Question 13

Pacinian corpuscle

Answer 13

Mechanical pressure
Pressure stimulates pacinian corpuscle
Layers of lamellae stretch and become deformed- causes axon membrane to stretch
Stretch mediated NA+ channels are stretched and NA+ diffuses in
This causes a generator potential- if it reaches the threshold an action potential will be produced

Question 14

How light passes to retina

Answer 14

Photoreceptors I’m the eye detect light

Light enters the eye through the pupil and is focused by the lens on the retina

Question 15

Rods

Answer 15

Found in periphery of retina
Many to 1 bipolar neurone
Rhodopsin

Doesn’t detect colour
High sensitivity
Low acuity

High sensitivity as…
Dim light stimulates each rod cell
Rhodopsin breaks down
Several rods are connected to one bipolar neurone- spatial summation of Ach- this leads to a generation potential
Threshold is passed and impulses move along shared bipolar neurone
Impulses reach the brain

Poor acuity as…
Light from 2 dots enters the eye and stimulates two rod cells
Several rods are connected to 1 bipolar neurone so spatial summation occurs- 1 generator potential produced
The threshold is passed and a single set of impulses move along one bipolar neurone
One set of impulses reach the brain so the person sees 1 dot

Question 16

Cones

Answer 16

Found in the fovea 
Single bipolar connection 
Iodopsin blue/green/red light bleaches 
Detect colour
High visual acuity 
Low sensitivity 

Low visual sensitivity…
Dim light stimulates the cone cells a little. Not enough to break down iodopsin
Each cone has its own bipolar connection. They’re not stimulated enough to cause generator potentials
Threshold is not passed so no action potential triggered
No impulses reach the brain

Good acuity…
Light from 2 dots enter the eye and stimulates 2 cones
Each cone has its own bipolar connection so 2 bipolar neurones produce generator potentials
The threshold is passed and separate impulses move along each bipolar neurone
2 impulses reach the brain so person sees 2 dots

Question 17

Control of heartbeat

Answer 17

The SAN in the wall of right atrium produces regular bursts of electrical impulses
It spreads across the atria causing them to contract together- can cross the wall between the 2 atria because it’s made of conduction tissue
Can’t pass to ventricular muscle because the atrioventricular septum is made of non-conducting tissue
Impulses reach the AVN
At the AVN- delay of 0.15s which allows ventricles to fill with blood before contraction
The AVN sends impulses along the purkyne fibres, down the septum into the apex of the heart and then up the ventricular walls
This causes the ventricles to contract from the apex upwards ensuring blood is pushed up and out of the heart

Question 18

How do baroreceptors work?

Answer 18

High blood pressure=high o2/low co2
Detected by chemoreceptors
Impulses sent along parasympathetic neurones to the medulla
Secrete Ach which bind to receptors in the SAN
Heart rate decreases

Low blood pressure= low o2/high co2
Impulses sent along sympathetic neurones to medulla
Secrete noreadrenaline which binds to receptors on SAN
Heart rate increases