Nervous system Flashcards
What are the specific functions of the nervous system?
Sensory input, integration and motor output
Stimulus – receptor – afferent pathway – integrated centre – efferent pathway
What is nervous tissue made up of?
neurons and neuroglia cells
What are neurons and what is their role?
Highly specialised nerve cells – Neurotransmission/synaptic transmission employing action protentional and neurotransmitters
What are neuroglia and what is their role?
includes many cells types that protect neurons
examples of neuroglia cells
largest glial cell found in the brain (CNS) are the astrocytes
smallest are microglial cells
neurones depend on having a constant internal environment, which is effected by the ……
blood- brain barrier (BBB).
What role do astrocytes have in the CNS?
Regulate movement of substances from blood into brain tissue, by bulbous cling to capillaries
provide physical structure and support for neurons
regulate the internal environment and neurons.
Maintain balance of Ca2+ and k+ ions
The Blood Brain Barrier is a highly selective membrane. What are some of the clinical implications of this high selectivity?
Restricts the movement of microscopic pathogens into the Central nervous system.
Draw and label a motor neuron
terminal buttons, presynaptic membrane, synaptic cleft, post synaptic membrane. Axon myelien sheath Node of ranvier axon hillock soma dendrite
What is the difference between sensory neurons and motor neurons
Sensory neurons are efferent pathway - receptors to CNS
Motor neurons run afferent pathway - CNS- affectors
Resting membrane potential is due too;
Unequal distribution of cations and anions between the inside and outside of the cell,
Examples of cations
sodium/potassium/calcium ARE POSITIVELY CHARGED
Examples of anions
chloride/fixed negatively charged proteins ARE NEGATIVELY CHARGED
what does depolarisation mean?
polarised means difference in charge so depolarised means it is become less charged. Resting is polarised when open channels it starts depolarisation
What is resting membrane potential?
Balance of positive and negative ions are across membrane results in negative resting membrane potential, intracellular proteins are fixed, by controlling the movement of sodium and potassium across the cell membrane. Membrane potential can be changed
what is action potential?
In response to the appropriate stimulus, the cell membrane of a nerve cell goes through a sequence of depolarization and repolarization
What is Nerve impulse conduction or propagation?
where action potentials are sequentially triggered along the length of the nerve cell membrane allowing for the signal transmission.
What is a myelin sheath?
Myelin Sheath is a many layered coating that protects and insulates the axon.
Made of fatty substance called myelin.
What are Nodes of Ranvier and their role?
Are gaps in the Myelin.
speed up propagation of action potential along the axon
what are autoimmune demyelinating conditions?
conditions that damage myelin (body creates antibodies that attack the mylien sheath). When this happens, scar tissue forms in its place. Brain signals can’t move across scar tissue as quickly, so your nerves don’t work as well as they should
List the events that occur at a synapse in order to perpetuate an impulse from one nerve to another
Step 1: Neurotransmitter synthesis
Step 2: Neurotransmitters packaging into vesicles (dopamine and ACH)
Step 3: release across synaptic cleft (exocytosis) (or Na2+) Ca 2+ ion gives instructions on how to cross. Opening channel in membrane
Step 4: Neurotransmitter binding - they now swim through synaptic cleft to the postsynaptic neuron which contains receptors and bind that translate the action potential from the vesicles. These channels let ions into the next neurone and travel along it and depolarising allowing action protentional.
Step 5: Receptors are cleared and recycled back to the presynaptic terminal to be degraded and turned back into neuro transmitters sometimes absorbed by postsynaptic terminal. Ready to repeat the cycle
Briefly explain the mechanism of action of Fluoxetine (Prosac)
delay the re-uptake of serotonin, resulting in serotonin persisting longer when it is released. Acting as an antidepressant and reduces anxiety
Neurotransmitter Excitatory and inhibitory chemical messengers allow…
neurons to communicate with each other at the synapse
Central nervous system:
part of the nervous systems that includes the brain and the spinal cord and coordinates the motor responses of the body.
Peripheral nervous system;
Part of the nervous system that includes all the nerves what are not in the brain or spinal cord.
Somatic nervous system:
Part of the nervous system that coordinates the voluntary movement of skeletal muscles, sensory input from the special senses and pro-proceptive sensation from mechano-receptors in skin, joints and muscles
Autonomic nervous system:
Is the functional part of the peripheral nervous system. that acts as a control centre to ensure homeostasis is maintained.
These activities are generally performed without conscious control including heart rate, digestion, respiration rate, salivation, perspiration, and diameter of the pupils, micturition (urination), and sexual arousal.
Sympathetic nervous system:
functions part of the autonomic nervous system that controls fight or flight response.
Parasympathetic nervous system:
Part of the autonomic that regulates SLUDD (Salivation, lacrimation (tears), urination, digestion, defecation.
Cranial Nerves
Part of the peripheral nervous system
Cranial Nerves
Part of the peripheral nervous system in the brain stem that control head and neck motor function
Spinal Nerves
peripheral nervous system. Nerves that originate in the spinal cord that control motor and sensory function of the body.
what is the Cerebral cortex
part of the brain that controls emotions and feelings, memory and sensation
functions of the Hypothalamus
controls homeostasis by linking nervous and endocrine systems.
what does the Mid brain control?
controls vision and hearing
what does the Cerebellum do?
important for the coordination, balance and perception.
What does the brain stem control?
contains the controls for breathing and the heart.
what happens in the Spinal cord
sensory information passing from the peripheral nervous system to the brain and motor information passing from the brain to muscles and glands found in the body
where is the Cortico-spinal tract and what doe sit do?
within the spinal cord
motor commands passing from the primary motor cortex to the ventral horn where upper motor neurons synapse with lower motor neurons
what are the Meninges
The 3 membranes which envelop the brain and spinal cord that consist of the Dura, arachnoid mater and pia mater whose primary function is to protect the central nervous system
what are Ventricles in the brain?
The cavities found in the brain and spinal cord that are filled with cerebrospinal fluid whose main functions are: buoyancy, protection, and chemical stability of the brain
what is the Circle of Willis
The collateral circuit of blood vessels that is Functional Anatomy of the Autonomic Nervous System
viscereceptors
receptors in the visceral organs and are attached to the autonomic sensory neurons.
measure the physical and chemical internal environment
Visceral organs
Heart, brain, lungs, blood vessels, urinary and gastational tracts
examples of viscereceptors
Chemorecepters - measure blood CO2
mechanoreceptors - detect the degree of stretch in the walls of organs or blood vessels
thermoreceptors - that measure temperature
baroreceptors - that measure blood pressure
visceral pain
Visceral pain occurs when pain receptors in the pelvis, abdomen, chest, or intestines are activated. We experience it when our internal organs and tissues are damaged or injured. Visceral pain is vague, not localized, and not well understood or clearly defined. It often feels like a deep squeeze, pressure, or aching.
Somatic pain
Surface pain: eg. scratches
Visceral pain occurs when pain receptors in the pelvis, abdomen, chest, or intestines are activated. We experience it when our internal organs and tissues are damaged or injured. Visceral pain is vague, not localized, and not well understood or clearly defined. It often feels like a deep squeeze, pressure, or aching.
Autonomic reflexes
are responses that occur when nerve impulses pass through an autonomic reflex arc. These reflexes play a key role in regulating controlled conditions in the body, such as: blood pressure: by adjusting heart rate, force of ventricular contraction, and blood vessel diameter; digestion by adjusting the motility (movement) and muscle tone of the gastrointestinal tract; defecation and urination by regulating the opening and closing of sphincters.
Dual innervation:
Sympathetic and parasympathetic divisions innervate mostly the same structures (e.g Gastrointestinal function)
Antagonistic action:
Sympathetic and parasympathetic divisions cause opposite effects (e.g heart function)
