Module 3 Homeostasis and Structure of the Nervous System Flashcards
Define homeostasis
The body maintaining a constant environment and changes in conditions that challenge its constant environment
Stages of maintaining homeostasis
Senses detect changes, integration centres stimulate effectors (interprets signals), effectors respond to changed conditions
Define positive and negative feedback
Whether the changes require a positive or negative feedback from body (concept)
What is positive feedback
When the environment is stable and constant, the body doesn’t have to do anything but continue its processes and maintain
What is negative feedback
When theres changes in the environment that the internal environment needs to adjust to and revert back to constant state. Adjustments cease when set point is reached
Difference between endocrine and nervous system
endocrine is slow, duration is long and more general, nervous is fast, duration is short more specific
What does the central nervous system (CNS) consist of
Brain, spinal cord,
what is part of the Peripheral nervous system
all other nervous tissue
describe features of the brain
Located in the cranial cavity, surrounded by meninges, bathed in cerebrospinal fluid (the brain moves around in this fluid and provides nutrients), dense collection of neurons (receiving info, integrated and determining what to do), has white matter (cable of information coming in and out of centre) and grey matter (Processing centre).
Name the 4 regions of the brain
Cerebrum, Diencephalon, cerebellum, brainstem
Which is the largest part of the brain
Cerebrum- generates conscious thought, responsible for memory, reasoning emotions
which region of the brain is the main junction for sensory inputs
Diencephalon
What is the fluid that protects the brain called and where is it formed
Cerebrospinal fluid, made in ventricles
Which region of the brain generates breathing patterns and heart rhythm
Brain stem
which cells produce cerebrospinal fluid
ependymal cells
which cells protect neurons from bacteria
microglial cells
Name the 5 spinal nerves and where they are
cervical(neck), thoracic (chest) , lumbar (abdomen), sacral (pelvis), coccygeal (tailbone).
What is a nerve
A collection of neurons
Define neuron
functioning cells generating an electrical signal, a nerve is a collection of them.
What is afferent
Afferent means it will come out and COME INTO the spinal chord and AFFECT the nervous system. Sensory nerve
What is efferent
Efferent is coming out of the central nervous system and is AN EFFECT of the CNS. Motor nerve
What parts of the body do spinal nerves receive/ transmit signals to
all over the body not so much the head
What parts of the body do cranial nerves receive/transmit signals to
Mostly the head, but vagus goes to all over the body.
Name the parts of a neuron
Dendrites, cell body, axon, axon terminal
How do neurons generate electrical signals
Occurs because of difference in charge over gradient, cation leaks out of cells and causes a charge
What is a voltage difference
Potassium leaks back out causing an imbalance inside becomes negative and outside becomes positive, allows neurons to generate electrical signals
How are signals stimulated
dendrites pick up signals, cell body integrates, sends to axon if threshold is reached an action potential is formed
where does action potential occur
at axon hillock
Where in the spinal cord do sensory neurons enter?
dosal surface (SAD)
Where is the most basic integration of sensory input?
at the receptor field and goes into the spinal cord
describe the path of a sensory stimulus from receptor ti the sensory cortex
- receptor field to spinal cord 2. up spinal cord to thalamus 3. thalamus to cortex
what is the most basic level of control of the somatic system
spinal cord
where in the spinal cord do motor neurons emerge from
ventral- efferent
what is the highest level of control of the somatic system
cerebellum
what is the parasympathetic system
rest and digest.
what are the effects of the cranial nerves
constrict pupils, saliva secretion, nasal secretion
what are the effects of the vagus nerve
increase secretion, muscle contraction, relax sphincter , glucose uptake(liver), contracts gallbladder
What are the vagus effects on the cardiovascular system
reduce heart rate, constrict bronchioles
what is the sympathetic system
fight or flight- from thoracic and lumbar nerves, ganglia in spinal cord or plexus
Give an example of negative feedback
Thermorecptors detect temperature, brain integrates signals and alters blood flow, alters muscle activity, alters behaviour, ceases alternation when normal
an example of positive feedback
a tear. platelet system: some platelets on site, release chemical to attract more, platelet plug is fully formed.
example of endocrine response
blood glucose. pancreas senses glucose, releases insulin, liver stores glucose, tissue takes up more glucose
example of nervous response
blood pressure. sensors detect decrease, brain integrates response, HR increases -vasoconstriction, BP returns to normal
what is the cation inside the cell
potassium
what is the cation outside the cell
sodium
how is an action potential formed- basic
axon reaches threshold, tells cell to transmit signal start AP occurs at axon hillock
describe the net effect
depolarisation- sodium enters cell, repolarisation - sodium stops entering, potassium leaves, hyper polarisation - too much potassium leaves cell.
describe saltatory conduction
Action potential propagating down a myelinated neuron. action potentials in myelinated neurons: gaps in myelin = nodes of Ranvier, AP travels faster down the axon
what is absolute refractory period
when an action potential cannot be created, occurs when there is already one in progress
what is relative refractory period
when it is difficult to stimulate an action potential (axon less sensitive), when cell is hyper polarised
what is a synapse
the gap between the action potential and target cell, signal to release neurotransmitter. neurotransmitter affects target cell
describe the components of the synapse
presynaptic neuron, postsynaptic target, synaptic cleft, neurotransmitter, receptor for neurotransmitter
describe the conversion of a signal
voltage gated sodium channels open in synapse and lets calcium in = vesicle binds membrane, vesicle releases neurotransmitter to synapse.
movement of which ion is mostly responsible for resting membrane potential
potassium and moves out of cells
which ion triggers vesicle fusion and neurotransmitter release in the axon terminal
calcium
what 5 structures does the cortex have
frontal, parietal, occipital, temporal, insular.
what functional areas does the cortex have
sensory, motor, association areas
name the functional associated areas
premotor and motor, somatosensory and somatosensory association, primary visual and visual association, auditory and auditory association
what is the pre-frontal cortex responsible for
memory and reasoning
what is the posterior association responsible for
sensing environment
what is the limbic system responsible for
emotions
where is the thalamus and what does it do
in diencephalon, relays sensory neuron input to sensory cortex(s)
where is the hypothalamus and what does it do
in diencephalon, involuntary signal integration, homeostatic control centre, regulates hormone secretion
what does the cerebellum do in terms of regulating signals
fine control of motor activity, received information from sensory receptors, motor cortex and sensory areas, fine tunes motor cortex output
what does the brain stem do
controls visual+auditory reflexes, regulates respiratory rate, controls heart rate, blood vessels, generates respiratory and GI reflexes
describe how a reflex occurs
reflex is generated in the spinal cord, opposed muscle sets in limbs cause flexion or extension, spinal cord inhibits one set and and stimulates the other to cause withdrawal. In crossed extensor, opposite signals in different limbs causes one to flex and one to extend
what does the parasympathetic system do
stimulates secretions from the salivary glands, nose and constricts pupils. reduces cardiovascular and respiratory activity, reduces heart rate and constricts airways. increases gastrointestinal activity, secretion, motility, glucose storage and bladder contractions
what effects does the sympathetic system have
increases heart rate, blood pressure, respiration, inhibits gastrointestinal system
