Nervous System Flashcards
What are the two sections that the nervous system is divided into?
CNS
PNS
What does CNS stand for?
Central nervous system
What is the central nervous system comprised of?
Brain and Spinal cord
What’s does PNS stand for
Peripheral Nervous System
What is the PNS made up of?
All the other neurons outside the CNS
What does the nervous system allow the body to do?
Allows the organism to react to the stimulus very quickly.
What are the responses like of nervous system?
Rapid and short
What are the two parts of the PNS?
- Sensory division
- Motor Division
Outline the role of the sensory division
Transmits information to the CNS
Outline the role of the motor division.
Transmits information away from the CNS
What are the roles of the somatic sensory neurons?
Transmits information to the CNS from the external environment via senses
What is the role of visceral sensory neurons?
Transmits information to the CNS from the internal environment e.g organ
What are the two systems of motor division?
Somatic Nervous System
Autonomic Nervous a System
What is the role of the somatic nervous system?
Transmits messages to skeletal muscles. This is a VOLUNTARY system
What is the role of the autonomic nervous system
It is an involuntary system
It sends messages to smooth muscles, heart muscle and glands as humans cannot control these things
What are the two sections of the autonomic nervous system
- Sympathetic
- Parasympathetic
Explain synaptic signalling
Nerve cells releases neurotransmitter molecules into synaptic celft, stimulating target cell
What are responses to the changed dectected by the nervous system like?
Rapid and short
What is a nerve cell called
A neuron
What sort of impulses do neurons transmit?
Electrical
Function:Cell body in neuron
Mass of cytoplasm with contains a nucleus, from which branches of neurons arise
Function: Axon
Carry information away from the cell body to another neuron or tissue
Function Dendrites
Recieve stimuli from other cells
Function Synaptic terminals
Communicate with other cells
located on the dendrites
Function myelin sheath
increases speed of electrical impulses and insulates against loss of impulses for the neuron
Function Nodes of Ranvier
Impulses jump from one to the next hence creating a more rapid impulse
(spaces in between the myelin sheath)
Function Axon Terminal
Release neurotransmitter to next cell
Three types of neurons
- Sensory
- Interneurons
- Motor Neurons
Function- Sensory neurons
Carry sensory information from the receptors to the CNS
Function- Interneurons
Form connections or links between other nuerons in the CNS
Function- Motor Neurons
Carry information from the CNS to the effectors to generate a response
Definition of a nerve
A bundle of motor neurons and or sensory neurons with tissue and bloo vesscles.
What initially begins action potential?
When a signal binds to a receptor on a dendrite it creates an electrical impulse which travels along the axon to the axon terminal
What happens when the electrical impulses reaches the axon terminal?
Releases a neurotransmitter which will either move to the enxt neuron or effector via brownian motion
Explain the resting state of a neuron
Potassium inside
Sodium Outside
Hence a resting state of an overall negative charge inside the neurone.
What happens to the membrane when the signal binds to the dendrite?
It becomes more permeable to sodium ions and they rush into the cell
What is known as action potential
The temporary charge outside the neuron when sodium ions rush into the neuron via the protein channels
Does action potential move in sections?
Yes
What happens after the impulse has moved along the neuron
It will return back to its resting state, and will repolarise
Define neurohormones
Hormones released into the bloodstream and are produced by neurosecretory cells
What is the synapses?
The region at the end of an axon
What are neurotransmitters?
Proteins in which are chemical messengers and exit the neurone via secretory vesicles. They will then diffuse across the synapse and join to protein receptors on the membrane of a dendrite, muscle or gland.
What are the two types of neurotransmitters?
Excitatory
Inhibitory
What is the neuromuscular junction
Synpase (gap) between a neuron and a muscle
Explain the ecitatoory synapse
- net low of positive charges into the cell, leaving the cell depolarised
- leading to becoming closer to threshold
Explain the inhibitory synapse
- Membrane pushes even more negative than the resting state
- Cell then becomes hyperolarised
- Reduced chance of action potential
Role of meninges in brain
Membranes which enclose the brain
Cerebrospinal fluid
Fluid between membrane acts as cushioning to the CNS when it recieves a knock
Cerebrum
Controls all concsious actions
Cerebellum
Coordination of complex muscle movement
Thalumus
Recieves impluses from the sensory neurons and directs the message to a part of the brain
Hypothalamus
Regulates the release of hormones and controls other aspects of homeostasis.
What is a reflex arc?
A pathway from a receptor to effector that does not involve the brain
How do reflex arc work?
involuntary movement directly controlled by the spinal cord
