Topic 6 - Flashcards
(17 cards)
What are the differences between a cholinergic synapse and a neuromuscular junction (4)
.Neuromuscular can only be excitatory, cholinergic can be inhibitory/excitatory
.Neuromuscular is between a motor neurone and muscle, Cholinergic is between any 2 neurones
.Neuromuscular is the end point of action potential (effector), action potential in Cholinergic is generated in the next neurone
.Neuromuscular the neurotransmitter binds to receptors on the muscle fibre, whereas cholinergic binds to receptors on post synaptic membrane of a neurone
What happens to length of different bands in a sarcomere when a muscle contracts
A band (length of myosin) - doesn’t change , remains constant
H zone (myosin on its own) - decreases because actin is moving inwards
I band (actin on its own) - Shortens , more of an overlap with myosin
Z line (indicate start and end of sarcomere, they are in I band) - They come closer together
Sliding filament theory (8)
1) Action potential reaches muscles, stimulating sarcoplasmic reticulum to release Calcium ions
2) Calcium ions enter and cause tropomyosin to unblock actin binding sites
3) Whilst ADP is attached to myosin head, myosin head binds to exposed binding sites on actin forming a cross bridge
4) Angle created by myosin binding creates tension p, causing a pulling/sliding action of actin along the myosin (called power stroke)
5) ADP and Pi are released in the power stroke
6) ATP then binds to myosin head, causing shape to change and results in myosin head deattatching from actin
7) Enzyme ATPase in sarcoplasm is activated by calcium ions, which hydrolyse the ATP on myosin heads into ADP and Pi, releasing enough energy to return myosin head to its original position.
8) Aslong as there’s enough stimulus to release Calcium ions, tropomyosin will move away and the process is repeated
What is Phosphocreatine
Chemical stored in muscles which provide phosphate to regenerate ATP from ADP
Describe structure slow twitch fibres (3) and where they are located
.Contains many mitochondria - for aerobic respiration
.Has a large store myoglobin (higher affinity than haemoglobin) - can hold and store a lot of oxygen until low partial pressure before it unloads
.Has a rich supply of oxygen - so it can constantly supply oxygen
These are located in the calf muscles
General properties of slow twitching fibres (2)
.They contract slower and can respire aerobically for longer periods of time
.These are adapted for endurance work
Describe structure of fast twitch fibres and their location (4)
.Thicker and more myosin filaments
.Large glycogen store
.Phosphocreatine store to help produce ATP
.Higher concentration of enzymes needed for anaerobic respiration
These are located in the biceps
General properties of fast twitch fibres (2)
.They contract faster to produce shirt burst of powerful contractions
.Adapted for intense excersise such as sprinting/weight lifting
Describe the second messenger model (for glucagon) (4)
1) Glucagon binds to complementary receptors on liver cells membrane
2) This causes an enzyme to be activated into adenylate cyclase, which converts ATP into cyclic AMP (cAMP)
3) cAmP activates enzyme Protein kinase that can hydrolyse glycogen into glucose
4) cAMP will also active other enzymes to convert glycerol and amino acids into glucose (gluconeogenesis)
What is the convention of glucose into glycogen
Glyconeogenisis
What is the hydrolysis of glycogen into glucose
Glycogenolysis
What is the creating of glucose from other molecule (such as amino acid and glycerol)
Gluconeogenesis
Type 1 diabetes
Body is unable to produce insulin, usually due to an autoimmune disease where Beta cells are attacked
Type II diabetes
When receptors on target cells do not respond to insulin, usually due to obesity/ poor diate
What is a stimulus
A detectable change in the environment , cells which detect these changes are called receptors
Taxes
A simple response where an organism will move its whole body towards a favourable environment (positive taxes) or away from an unfavourable environment (negative taxes)
There can be positive chemotaxes where an bacteria move towards a chemical to aid survival
Kinesis
A simple response where organisms change the speed of movement and the rate it changes direction.
In a favourable environment they increase rate at which they change they direction to remain in the favourable environment, rate of turning also increases if they just cross the boundary to an unfavourable environment, but if surrounded by unfavourable conditions, rate of turning decreases.
