Quiz 1 Flashcards
The nervous system contains
Brain, spinal chord and nerves which connect to the rest of the body
- maintain homeostasis- relative stability of the body
Divisions of the nervous system
CNS- consist of the brain and the spinal cord
-Integrates and processes information
PNS- links the CNS with the body
Somatic
Control, skeletal muscle bone and skin
-Under conscious control
Sensory: carries information from the body to the CNS
Motor: carries information from the CNS to the body
Autonomic
Involentary
- regulates and maintains homeostasis
-Consist of sympathetic and parasympathetic systems that work in opposition
Sympathetic
Activated in stressful situations
- Cause increase in heart rate, blood pressure, breathing, dilation of the airways, blood pressure, dilation of the pupils
-decreased digestion in urine production
Parasympathetic
Ask to restore and conserve energy
- increased digestion and urine product
-Decreased heart rate, breathing, pupil, and airway, dilation, blood pressure.
Cells of the Nervous System
Neutron: functional cell of the nervous
- Have an excitable cell membrane, which can conduct an electrochemical impulse
- group is called a nerve
Glial cells: support cells for the nervous system
-Nourishes, neurons, removes waste, defence against infection, supporting framework
3 main types of neurons
Sensory neurons: gather information from sensory receptors and transmit impulses to the CNS
Interneurons: act as a bridge between sensory and motor neurons. Process sensory information and relay outgoing motor information.
Motor neurons: transmit information from the CNS to effectors
Dendrites
Projections of a cell body/cytoplasm that carry impulses towards the cell body
Axon
Projections of the cell body that carry impulses away from the dendrites
-impulse carry towards other neurons or effectors
Synaptic Knob
End of the neuron where the cell synapses with another neuron effector
Myelin Sheath
Insulation for the neuron
- formed by Shwan Cells
- white coat of fatty protein
- prevents loss of charged ions from axon
- helps increase speed of nerve impulses
Nodes of Ranvier
Sections between the myelin
Neurolemma
Membrane around nerve fibres within the PNS that promote the regeneration of damaged axons.
White and Grey Matter
White- contains myelin and neurilemma
Grey- does not contain myelin or nuerilemma
Electrochemical impulse
An electrochemical message created by the movement of ions through the nerve cell membrane
Action potential
Reversal of charge across the membrane
Resting membrane potential/polarization
: Net negative charge of -70 mV
- inactive or resting neuron
- Charge difference is caused by an unequal concentration of positive ions outside the cell
- 3 sodium ions are pumped out for every two potassium ions that are pumped in
- Inside is therefore negative compared to outside
Depolarization
The reversal of charge were the inside of the membrane is more positive relative to the outside
- Caused by a stimulus, causing sodium channels to open and allow the diffusion of sodium ions into the cell
- This depolarization one area causes neighbouring sodium channels to open
- Wave of depolarization
Re-polarization
Refers to the restoring to original polarity
Sodium channels close in potassium channels open then quickly close
Sodium/potassium pump is operation
Causes the membrane to overshoot two approximately -90 mV before quickly being brought back to normal resting potential
Refractory period
The time required before neuron can produce another action potential
Threshold level
The minimum level of a stimulus required to produce a response, approximately 55 mV
All or non-response
A neuron will either fire maximally or not at all, more intense to stimulus the greater the frequency of the impulses
Saltatory conduction
In myelinated neurons, action potential occur only at the nodes of Ranvier
- Nerve impulse to spread down the axon by saltatory conduction
