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A2 Coordination Cheat Sheet (DRAFT) by

This cheat sheet highlights important points about the topic Co-ordination and response of IGCSE AL CIE Biology chapter 15.

This is a draft cheat sheet. It is a work in progress and is not finished yet.

Nervous & Endocrine systems

 
Nervous system
Endocrine system
Commun­ication
Action potent­ial­/Im­pulses
Hormones
Nature of commun­ication
Electrical (& chemical)
Chemical
Mode of transm­ission
Neuron­es/­Nerve cells
Blood
Response destin­ation
Muscle­s/G­lands
Target organs­/Ti­ssu­es/­Cells
Transm­ission speed
Faster
Slower
Effects
Specif­ic/­loc­alised
Widespread
Response speed
Faster
Slower
Duration
Short-­liv­ed/­Tem­porary
Long-l­ast­ing­/Pe­rmanent
Receptor location
On cell surface membrane
On cell surface membrane or within the cell
ATP requir­ement
Higher
Lower
Both systems involve cell signaling, chemicals & signal molecules binding to receptors.

Defini­tions

Dendrites
Thin, short and highly branches cytopl­asmic processes extend from the cell body.
Receptor cells
Cells that respond to a stimulus by initiating an action potential.
Transd­ucers
Convert energy from one form into energy in an electrical impulse in a neurone.
Reflex arc
The pathway along which impulses are transm­itted from a receptor to an effector without involving the conscious regions of the brain.
Reflex action
An immediate response by an effector to a specific stimulus without involving the conscious regions of the brain.
Neurot­ran­smi­tters
Chemical messengers that are released from neurons and they are used to stimulate another cell.

Structure of the sensory & motor neurones

 
Sensory neurone
Motor neurone
Function
Transmits impulse from receptors to the CNS.
Transmits impulse from the CNS to the effectors.
Cell body
In the middle of the neurone and NOT within the CNS.
At the end of the neurone and within the CNS.
Axon
Short
Long
Dendrites
Attached to dendron.
Attached to cell body.
Terminal branches
present
present
$ The dendrites provide large surface area for the axon terminals of the other neurons.
$ Relay neurons are found entirely within the CNS & they transmit impulses from the sensory to the motor neuron.
  

Role of a chemor­eceptor cell (in human taste buds)

1. Chemicals act as a stimulus.
2. Chemor­ece­ptors are specific in detecting taste and they are transd­ucers.
3. Na+ diffuses into the cell upon the stimul­ation of the receptor, via microv­illi.
4. The membrane gets depola­rized.
5. Ca2+ channels are stimulated to open and Ca2+ enter the cell.
6. This causes the movement of vesicles containing neurot­ran­smi­tters, and the neurot­ran­smi­tters are released by exocyt­osis, stimul­ating an action potential.