The Nervous System Flashcards
difference between central nervous system and peripheral nervous system
CNS: brain and spinal cord
PNS: cells called nerves branching from CNS to all of body
What is the nervous system responsible for
allows organisms to react correctly to stimulus in their environment so that they can survive
Def. of stimulus
Any change in our environment
Impulse def.
An electrical message that is carried along a nerve cell
Receptor def.
A sense organ that detects the stimulus.
Eg. Eye, Ear, Nose
Effector def.
Receives a message and carries out the action/ response
eg. Muscle/Gland
Nerve cells
Function
another name
types
Function: carry impulses to and from the CNS to allow us to react correctly to stimulus
Another name: Neurons
Types:Sensory, Inter, Motor
Sensory neuron function and other name
Function: Carries impulses from Receptor to the CNS
Another name: Afferent Neuron
Interneuron
Function
Another name
Function:Connects sensory and motor neurons and carries messages within CNS-within brain and spinal cord to brain
Another name: Intermediate/Relay/Association
Motor neuron
Function
Another name
Function: Carries messages from CNS to Effector
Another name: Efferent
Process of response
- Stimulus occurs
- Receptor detects stimulus
- Sensory neuron sends impulse to CNS, Interneuron sends impulse to brain.
- Brain decides on a response
- Motor neuron sends an impulse to the effector.
- Effector carries out response
Structure of a neuron
Three types
(in direction of impulse)
Receptor-Dendrites-Dendron-axon hillock-cell body(soma)-axon-axon terminal
Along dendron/axon: The myelin sheath-schwann cells. Node of Ranvier in between schwann cells
Sensory: soma/Cell body sticks up and receptor at start.
Inter: Soma is on the dendron in the middle
Motor: Soma is near dentrites-no dendron, effector at end.
Functions of cell body
contains nucleus
makes other parts of the neuron
connects to the dentrites and passes the impulse to the axon
Functions of dendrite
Nerve endings
connects to another neuron or receptor and receives the information/impulse
Functions of dendron
Short fiber that receives information from the dendrite and carries it toward the cell body
Functions of axon
carries impulses away from cell body
Functions of axon hillock
part where cell body connects to axon
Functions of schwann cell and myelin sheath
makes the myelin sheath which insulates and protects the neuron.
Functions of node of ranvier
gap between each schwann cell.
speeds up the impulse
Functions of axon terminal
release chemicals known as neurotransmitters to pass the impulse to the next neuron
Other names for axon terminal
terminal knob,
synaptic knob
Disorder of the nervous system Name Causes Symptoms Prevention treatment
Name: Parkinsons
Causes: Lack of dopamine (controls muscle contraction)
Symptoms: muscles become rigid, movement slow, movement difficult and painful, tremors
Prevention: no means of prevention
Treatment: giving L-dopa (converted to dopamine in body), physio, exercise with balancing and stretching, speech therapy, surgery to stimulate brain
Endocrine system vs. Nervous system Cells involved Message type Carried by Received by Speed of transmission Effects Duration
Cells involved: glands-sense receptor Message type: chemical-electrical Carried by: blood-neuron Received by: target organ-effector Speed of transmission: slow-fast Effects: widespread-localised Duration: long lasting-brief
Structure of brain
- skull
- lining skull (2 parts)
- big brainy thing
- like a heart
- smoother thing near big brain
- seahorse thing-bottom (6), tummy (7),head (8)
- centre of everything
- dotty thing near seahorse
- Cranium
- Meninges and cerebro-spinal fluid
- Cerebrum
- Cerebellum
- Corpus Callosum
- Medulla oblongata
- Pons
- Pituitary gland
- Thalamus
- Hypothalamus
What are the left and right sides of the brain referred to as
Hemispheres
Function of Cerebrum
Controls language, memory, intelligence and consciousness
Function of cerebellum (bella the ballerina)
Muscle coordination, movement and balance
Function of medulla oblongata
obligated to
Controls breathing and heart rate
Function of Meninges and Cerebrospinal fluid
Protects brain
Meninges-lining of fluid
Function of Hypothalamus
secretes hormones to control the pituitary gland
near to the pituitary
Function of Corpus Callosum
Connects right and left sides/hemispheres
Function of Pituitary gland
Secretes hormones to control other glands
Function of Thalamus
Sorting centre of all the messages that the brain receives and sends the message to the correct part
Where are the following located on the cerebrum
- intelligence, memory, consciousness, language
- Vision
- Smell
- Hearing
- Taste
- Speech
- Motor control
- Sensory control
- front
- back (eyes at the back of the head)
- Underneath
- Centre
- Centre
- Centre
- Top
- Top (behind 7.)
* (for 3-6 think of where they are positioned in the head)
Right hemisphere functions
Controls left side of body
Art, Music etc.
If strong right side often left handed
Left hemisphere
Controls right side of brain
Language, Maths
*right handed
Transmission of impulse from one neuron to next process
- Pre-neuron transmits impulse
- Impulse arrives at synaptic knob
- Vesicles containing the impulse move to the edge of the knob
- Vesicles open releasing neurotransmitters to carry the impulse to the post neuron
- The neurotransmitters bind to the receptors on the post neuron
- The impulse is generated on the post neuron and travels along the neuron.
What is the point where a pre neuron meets a post neuron called
a synapse
What is a synaptic cleft
the space between neurons in a synaps
Why are neurotransmitters needed at a synaps
Impulses are electrical and cannot cross a synaptic cleft. the impulse must be chemical to cross. neurotransmitters change the impulse to a chemical impulse
Neurotransmitters def.
type of particle
example
Def: Chemicals released from the pre neuron to carry the impulse to the post neuron. Released from vesicles and bind to receptors
Type: Ions
Examples: Dopamine, Acetylcholine, Noradrenalin
Inactivation of neurotransmitters
What it is
Why important
Once they have carried the impulse across the synaptic cleft they are broken down and digested by enzymes in the post neuron. they return back to vesicles on the pre neuron to be reused.
Important to prevent over stimulation of the post neuron and over firing of impulses
Threshold def.
the threshold is the minimum stimulus that is required to cause an impulse to be sent.
A stimulus below the threshold won’t send an impulse
One above will
All or nothing law
states that if the threshold is reached an impulse is carried, if the threshold is not reached an impulse will not be carried. Impulse is either carried or not.
Refractory period
The short period of time after a neuron has sent an impulse that a stimulus can cause no response on the neuron. ie. the neuron has a short rest
Importance of a synaps
Allows an impulse to be sent between neurons.
It prevents the over stimulation of effectors.
It controls the direction of impulses- neurotransmitters are only found in the terminal knobs
Reflex action def.
examples
advantages
A reflex action is a very fast unconscious, involuntary response to an unexpected stimulus
Eg. Knee jerk reaction, Blinking, moving finger away from flame
adv: Protects from damage
What is a reflex arc
Is a specific nerve pathway involved in this fast unconscious response to an unexpected stimulus.
Pathway of a reflex arc
and diagram
- Receptor
- Sensory neuron
- Spinal cord, brain
- Interneuron
- Motor neuron
- Effector
Diagram: Dorsal root (enter via the door), Dorsal root ganglion, ventral root, White matter (outside), Grey Matter (inside), Neural canal (centre)
Dorsal root ganglion function
swelling in the dorsal root caused by the cell body of the sensory neuron sticking up
Spinal cord function
protected by
Function: Transmits impulses to and from the brain
Protected by: vertebrae, meninges, cerebrospinal fluid
White matter vs. Grey matter
White matter: On outside-contains axons
Grey matter: On inside- contains cell bodies and dendrites
