Biology F214 Revision Thread 2013 JAN 11th

that's a lot of differences but let me give it a go !

-Sensory neurones have processes called dendrons
-Motor neurones have a single long axon
-Motor neurones have many short processes called dendrites from its cell body*
-Motor neurones carry impulses to effectors such as muscles and glands
-Sensory neurones carry impulses to the CNS

Let me give you one back what is saltatory conduction?

I was wondering if someone could help me out on the ascending and descending limbs of the loop of henle? I just dont get exactly how it works (movement of water out of the descending limb and active transport of sodium ions out ascending limb into the medulla) I'd be really grateful if someone cleared it up for me !

I was wondering if someone could help me out on the ascending and descending limbs of the loop of henle? I just dont get exactly how it works (movement of water out of the descending limb and active transport of sodium ions out ascending limb into the medulla) I'd be really grateful if someone cleared it up for me !

Got my mock tomorrow so every little helps

It is the jumping of action potential from one node of ranvier to the next.

Comon more of a difficult question!!!

Outline the process of an action potential.

In anaerobic conditons, pyruvate does not proceed to the link reaction, describe what happens to pyruvate during anaerobic respiration in an animal cell, what is the importance of the reaction?

Pyruvate enter the lactate fermentation cycle. This is important because reduced coenzyme NAD becomes oxidised in this reaction and then used again in the glycolysis cycle so a net gain of ATP (2) can be used for energy. The hydrogen acceptor and enzyme pryuvate dehydrogenase oxidises reduced NAD to form NAD.

It is the jumping of action potential from one node of ranvier to the next.

Comon more of a difficult question!!!

Outline the process of an action potential.

This gives a nice visual representation of the loop of henule

http://www.biologymad.com/resources/kidney.swf

Cliffs-
-The descending limb of the loop of henule is permeable to water.
-Therefore water moves out of the loop via diffusion.(Osmosis)
-This is because the loop of henule has a higher water potential than the surrounding tissues (medulla).
-
-Now the concentration of sodium is higher than the surrounding tissue. ( So some diffuses out)
-
-The acsending limb is imperamable to water.
-However Sodium is actively transported out.
-This produces a low water potential in the medulla.

Hope this helps

Pyruvate enter the lactate fermentation cycle. This is important because reduced coenzyme NAD becomes oxidised in this reaction and then used again in the glycolysis cycle so a net gain of ATP (2) can be used for energy. The hydrogen acceptor and enzyme pryuvate dehydrogenase oxidises reduced NAD to form NAD.

haha ! well done though !

My answer:
A stimulus occurs at the receptor (e.g. touch) and sodium ion channels in the plasma membrane open allowing sodium ions to flood into the cell because of the "double gradient" known as the electrochemical gradient. the resting potential is gone after a short amount of time and the inside of the axon is no longer more negative than the outside so the membrane is depolarised. Sodium ion channels then close and the potassium ion channels open to let out potassium ions via diffusion and this removes the positive charge from inside the axon. The charge across the membrane then becomes normal again and the membrane is repolarised. However so many potassium ions leave the axon that the inside of the axon becomes more negative than the resting potential causing the membrane to be hyperpolarised causing potassium ion channels to close. the sodium potassium pump then restores the resting potential (refractory period).

lol sorry about the long answer but here's a harder question . How does an action potential travel across a synapse ?

Alcohol is absorbed via the duodenum, it flows into the liver via the portal vein (I think). Alcohol is broken down by enzymes to form Acetalhyde + 2H. Acetalhyde is then converted futrher by ALDH into an Acetyl radical +H.

Thats all I can remember of that

Thats a very detailed response , you don't need as much info as that buddy but you do know your stuff!

Impulse arrives at synaptic knob
Potential difference changes in the synaptic knob
Voltage gated calcium ion channels open
Calcium ions diffuse into the axon.
Calcium ions bind onto the vesicles containing the neurotransmitter acetylcholine
Vesicles bind to the pre-synaptic membrane
Leave by exocytosis
Acetylcholine binds on complementary receptors on the post synaptic membrane
Sodium ion channels open on post synaptic membrane
Sodium ions diffuse down the synaptic cleft
Sodium ions enter the post synaptic membrane.

What text book do you use?
I'm not familiar with Acetly radical , I think your over complicating yourself!

Alcohol is absorbed via the duodenum, it flows into the liver via the portal vein (I think). Alcohol is broken down by enzymes to form Acetalhyde + 2H. Acetalhyde is then converted futrher by ALDH into an Acetyl radical +H.

Thats all I can remember of that

I think you mean Acetaldhyde? I learnt the detoxification of alcohol as this:
alcohol dehydrogenase catalyses the breakdown of alcohol into acetaldehyde and the enzyme aldehyde dehydrogenase converts it to acetate which enters the krebs cycle and 2 reduced NAD are formed in the process.

so ethanol from alcohol becomes ethanal (by alcohol dehydrogenase) and then converted to ethanoate (by aldehyde dehydrogenase). hope this cleared things up ?

I think you mean Acetaldhyde? I learnt the detoxification of alcohol as this:
alcohol dehydrogenase catalyses the breakdown of alcohol into acetaldehyde and the enzyme aldehyde dehydrogenase converts it to acetate which enters the krebs cycle and 2 reduced NAD are formed in the process.

so ethanol from alcohol becomes ethanal (by alcohol dehydrogenase) and then converted to ethanoate (by aldehyde dehydrogenase). hope this cleared things up ?

Yeah that rings a bell! ty

If you don't mind me asking, what revision techniques are you using?