15.1 Flashcards
What happens as species evolved?
Their cells become adapted to perform specialist functions
By specialising in one function , cells lost the ability to perform some other functions
What do different groups of cells each have?
Carry out their own function
Makes cell dependent upon each other to cary out functions they aren’t specialised in
Example of cells working together
Cells in reproduction
Depend on other cells to obtain oxgen for their respiration to provide glucose or remove their waste products
What are the two forms of coordination in animals as a whole?
- The nervous system
- The hormonal system
What does the nerve system use?
- They use nerve cells to pass electrical impulses along their length
- They stimulate their target cells by secreting chemicals known as neurotransmitter directly on them
- Results in rapid communciation betwen part of organisms
- Responses produced are often short-lived and restrictied to localised reigon of body
What is an example of nervous coordination?
Reflex action
e.g withdrawl of hand fom an unpleasant stimulus
What is the hormonal system?
- Produce chemicals (hormones) that are transported in blood plasma to their target cells
- The target cells have specific receptors on their cell-surface membrane - change of concentration of hormones stimulate them
- This results in slow, less specific form of communication between parts of organism
- Responses are often long-lasting and widespread
An example of hormonal coordination
Control of blood glucose concentration
Produces a slower response but has amore long term and widespread effect
Comparison of nervous system
- Communication by nerve impulses
- Transmission is by neurones
- Transmission very rapid
- Nerve impulses travel to specific parts of the body
- Response is localised
- Response is rapid
- Response is short-lived
- Effect is usually temporary and reversible
Comparison of hormonal system
- Communication is by chemicals called hormones
- Transmission by blood system
- Transmission is usually relatively slow
- Hormones travel to all parts of body , only target cells respond
- Response is widespread
- Response is slow
- Response is often lasting
- Effect may be permanent and irreversible
What are neurones?
(nerve cells)
Specialised cells adapted to rapidly carrying electochemical changes called nerve impulses from one part of the body to another
What are the parts of motor neurone?
- Cell body
- Dendrons
- Axon
- Schwann cells
- Myelin sheath
- Nodes of Ranvier
What cell body?
Contains all the usual cell organelles including a nucleus and large amounts of RER
This is associated with production of proteins and neurotransmitters
What is dendrons?
Extension of the cell body which subdivide into smaller branched dibres called dendrites that carry nerve impulses towards the cell body
What axon?
A single long fibre that carries nerve impulses away from the cell body
Diagram of labelled motor neurone
