15.1 Neurones and nervous coordination Flashcards
nervous system
use nerve cells to pass electrical impulses along their length
stimulate target cells by secreting neurotransmitters
rapid, short-lived and localised response
hormonal system
produce hormone chemicals that are transported in blood plasma to target cell
target cells have specific receptors on cell surface membrane and change in hormone concentration stimulates them
slower, less-specific communication
long-lasting and widespread
neurone
specialised cell adapted to rapidly carrying electrochemical changes(nerve impulses) from one part of the body to another
mammalian motor neurone
- cell body
- dendrons
- axon
- schwann cells
- myelin sheath
- node of Ravier
cell body
contains usual cell organelles
-nucleus
-rough endoplasmic reticulum
associated with production of protein and neurotransmitters
dendrons
extensions of cell body
- subdivide into dendrites
carry nerve impulses towards body cell
axon
single long fibre that carries nerve impulses to axon terminal and away from cell body
schwann cells
surround axon by wrapping around it- many layers of membrane built around it
protecting axon and provide electrical insulation
carry out phagocytosis and play part in nerve regeneration
myelin sheath
forms covering of axon
made up of membranes of schwann cells
- rich in lipid myelin
nodes of Ranvier
constrictions between adjacent Schwann cells where there is no myeline sheath
sensory neurone
transmit nerve impulses from receptor to intermediate or motor neurone
one dendron that is very long
-carries impulse toward cell body
one axon that carries away form cell body
motor neurone
transmit nerve impulses from intermediate or relay neurone to an effector
long axon and many short dentrites
intermediate or relay neurone
transmit impulses between neurones
have numerous short processes
