Chapter 13 (Neuronal Communication) Flashcards
How does the Pacinian corpuscle convert mechanical pressure into a nervous impulse
1) In the resting state, stretch mediated sodium ion channels are closed, so the Pacinian corpuscle has a resting potential
2) Pressure= surrounding membrane stretches
3) Therefore, sodium ion channels widen and diffusion occurs
4) An influx of positive ions depolarises the membrane = generator potential
5) Generator potential creates an action potential (nerve impulse) and passes along the sensory neurone
How is a resting potential established?
1) Sodium-potassium pump moves 3 Na+ ions out and 2 K+ ions into the axon
2) Therefore, there mare more Na+ ions outside the membrane and more K+ ions inside, so both diffuse down their respective electrochemical gradients
3) However, most gated sodium ion channels are closed but potassium ion channels are open, meaning that only K+ ions can diffuse, resulting in a positive outside and negative inside (resting potential of -70mv)
What is the value of resting potential across a membrane?
-70mv
What are the stages of myosin binding to actin in the sliding filament model?
1) Tropomyosin blocks binding site on actin molecule
2) Ca2+ ions released from endoplasmic reticulum causes tropomyosin to move away from the binding sites
3) Myosin head (with ADP molecule) attaches to the binding site on actin filament
4) Myosin head changes angle, moving actin filament and ADP is released
5) ATP molecule attaches to myosin head, causing the head to detach from actin
6) Hydrolysis of ATP to ADP provides energy for myosin head to go back to its original position
7) Myosin head attaches to actin binding site further along and the cycle is repeated
What are the cells called that make up the myelin sheath?
Schwann cells
Where is the cell body on a sensory neurone?
Cell body is found on an offshoot from the axon/dendron
Where is the cell body on a relay neurone?
Cell body is near the start of the neurone, connected to the dendrites by a short dendron
Where is the cell body on a motor neurone?
Cell body is at the start of the neurone, where all the dendrites meet
When is ADP released from myosin?
When the myosin head changes angle while bounded to the actin
What is the Cerebrum and what does it do?
Made up of the 4 lobes, controls voluntary actions
What is the cerebellum and what does it do?
Controls unconscious functions
What is the Medulla oblongata and what does it do?
Part below the pituitary gland, used on autonomic control
What does the hypothalamus do?
Regulatory centre for temperature and water balance
What does the pituitary gland do?
Store and release hormones
