Chapter 13 Neuronal Communication Flashcards
Describe why co ordination of communication systems is needed
Organisms need to co ordinate the function of different cells and systems to operate effectively and produce the required response.
What is homeostasis?
The maintenance of a stable equilibrium of internal body conditions through co ordination.
What is cell signalling?
The process in which a cell releases a chemical which in turn has an impact on another cell, known as the target cell.
What is the purpose of cell signalling?
-Transfer signals locally eg neurotransmitters
-Transfer signals across large distances eg hormones
State examples of an organisms internal environment that need maintaining
Blood glucose concentration
Internal temperature
Water potential
Cell pH
State examples of an organisms external environment that need maintaining
Humidity
External temperature
Light intensity
New/ sudden sound
What is the function of the nervous system?
The transmission of an electrical impulse along neurones.
What is the function of the endocrine system?
Release hormones in blood to target organs
State the function of neurones
Transmit electrical impulses rapidly around the body so the organism can respond to stimuli in its internal and external environment.
State the different types of neurones
Motor neurone
Sensory neurone
Relay neurone
State the function of a sensory neurone
Transmit impulses to the CNS from sensory receptors.
State the function of a motor neurone
Transmit impulses from the CNS to an effector (muscle or gland)
State the function of a relay neurone
Found in the CNS and transmit impulses between sensory and motor neurones
What are receptors?
Receptors are specific to detect a particular form of of stimuli
What are effectors?
Cells which provide a response to a stimulus, producing an effect.
Muscles and glands
What is the negative feedback mechanism?
Negative feedback systems work to reverse the initial change and restore conditions to their base level.
A small change in one direction will be detected by a sensory receptor, as a result effectors will work to then counteract the change.
What is the positive feedback mechanism?
Positive feedback systems work to amplify the initial change.
A change in the internal environment of the body is detected by sensory receptors and effectors are stimulated to reinforce this change.
Outline the process of neuronal communication
A stimulus is detected by sensory receptors
The impulse is transferred along the sensory neurone
The impulse is sent along the relay neurone in the CNS
The CNS processes information and decides how to react
The impulse is then sent along motor neurones to the effector cells to stimulate a response.
What is a sensory receptor?
Detects stimuli and converts it into an electrical impulse known as a generator potential which is then sent onto a sensory neurone by acting as a transducer.
Why are sensory receptors known as transducers?
Receptors change one signal into another form.
State some examples of sensory receptors
Photoreceptors- sight
Mechanoreceptors- pressure
Sound receptors- noise
Chemo receptors- scent/ taste
Thermo receptors - temperature
Spatial receptors
State the role of the Pacinian Corpuscle
Mechanoreceptor which can detect pressure changes
Describe how a resting potential is maintained within the Pacinian Corpuscle
- No pressure is applied meaning the stretch mediated Na ion channels remain closed
-Therefore, resting potential is maintained because there is a higher concentration of Na ions outside the neurone.
Describe how pressure changed can activate the Pacinian Corpuscle
- When pressure is applied the capsule changes shape causing the neurone membrane to stretch
- This causes the stretch mediated Na ion channels to open and allows an influx of Na+ to move via diffusion into the sensory neurone down an electrochemical gradient
-Depolarising the membrane initiating a generator potential
-Action potential is then propagated down the neurone
Describe the structure of the sensory neurone
-Short dendrites with a long dendron to carry the nerve impulse from the receptor cells to the cell body
-Short axon that carried impulse from the cell body to CNS
Describe the structure of the motor neurone
Short dendrites that carry nerve impulse from CNS to cell body
Long axon that carries nerve impulse from cell body to effector cells
Describe the structure of the relay neurone
Short dendrites which carry nerve impulse from the sensory neurone to the cell body
Short axon which carried the impulse from the cell body to motor neurone
Describe the structure of the myelin sheath
Schwann cell produces layers of lipids which act as an electrical insulator to speed up nerve impulse transmission via saltatory conduction at the nodes of ranvier
