Nervous System Flashcards
Nervous system division
Central and peripheral
Pressure receptors vary
in number around the body,
Less pressure receptors means
less messages
NS primary functions
sensory input, integration, motor output, controls all other body systems
CNS functions
the coordinator, it makes sense of the messages it receives from PNS,
CNS coordinates repsonses by
muscle and glands
Cns made up of
brain and spinal cord
PNS made up of
bundles of neves that branch off brain and spinal cord
PNS coordinates responses by
relaying meesages between sense organs and the CNS
Nervous tissue is
very concentrated in cells
Neurons are specalised cells that send and receive
electrical messages across the body
Neuron messages pass in the form of
one way nerve impulses
Neurons consist of:
cell body, dendrites, axon, myelin sheath,
Cell body
where the nucleus is located similar to a regular cell
Dendrites
branches off the nerve (receiver)
Axon
Thread like structure that carries impulses to other nuerons,
Myelin Sheath
fatty layer that insulates axon and dendrites to prevent signals from crossing, increases speed
Types of neurons
three (interneurons, motorneuron, sensory neurons)
motor neurons
transmit messages from CNS to effectors, connect directly to muscle tissue
sensory neurons
specialised receptors (to stimuli like heat or light) transmit messages from receptors to the CNS, connect directly to sensory receptors
Interneurons
transmit messages from sensory neurons to motor neurons and to brain, involved in reflex action
Synapses are:
the meeting point between two neurons
Synapses work:
action potential releases chemicals, vessicles transport to receptors, triggers new electrical signal
Presynpatic and postsynaptic cleft is
sender and receiver of chemical signals
An action potential is
a rapid sequence of changes in the voltage across a membrane
How do vessicles form
Presynaptic cleft chemicals merge with membrane
How do chemicals get removed
reuptake (reabsorbtion of chemicals) or diffusion (moves away)
Receptors are
cells that allow us to detect different types of stimuli
Chemoreceptors
sensitive to chemicals and are located in the nose and tongue
Mechanoreceptors
are sensitive to touch, pressure, sound and motion and are located in the skin, the inner ear and muscles
Thermoreceptors
are sensitive to temperature changes and are located in the skin
Photoreceptors
are sensitive to light and are located in the eyes
Pain receptors
are sensitive to chemical changes in damaged cells and are located throughout the body but most are located in the skin
Taste and smell both involve
the use of chemoreceptors
Internal organs use chemoreceptors
to detect changes in the environment
Organs and tissues can detect changes
in chemicals such as oxygen, carbon dioxide and PH
axon terminal
Part of neuron where passes the message to the next neuron
Effectors
muscels or glands that trnsalte the messages into action
glands
(tissues that secrete hormones)
neurotransmitter
chemical released into synapse, carries from presynaptic to postsynaptic cleft, control which nerves fire and when
nerves
bundled up neurons
white and grey matter
white - parts of CNS that contain neurons covered in myelin
grey - parts of CNS that contain unmylinated neurons
The brain
regulates and controls body functions
Hypothalamus
small region located deep in brain
controls body temperature, hunger and thirst, circadian rhythms, and the release of hormones from the pituitary gland
CNS protection
cranium protects brain
vertabrae protects spinal cord
cerevrospinal fluid surrounds all of it which provides nutrients and shock absorber
stimulus response
stimulus - receptor - sensory nerve - internrurons - motor neuron - effector - response
reflex action
involuntary and fast action
