Exam 1 - Ch.2 Structure of the nervous system Flashcards
What are the 3 functions of the nervous system? (These are also the types of neurons)
- Sensory: monitors internal and external environment
- Integration: interpretation an processing of sensory information; complex functions
- Motor: response to information processes through stimulation of effectors
What are the two types of neural cells?
- neurons: form circuits that constitute the structural basis for brain function
- glial cells: provide support, regulation, and protection of neurons
What are the basic structures of the neuron? What do they do?
- dendrites: receive info
- cell body: metabolic center of the axon
- axon hillock
- axon: transport of substances and neural impulses (AP)
- myelin sheath: AP travels faster on these
- axon terminals/terminal buttons: NT release
What things provide strength and aid in the transport of materials along the length of an axon?
- neurofilaments, actin, and microtubules
How many glial cells are found in the CNS? PNS?
- 4
- 2
Astrocytes
- most abundant
- development and maintenance of BBB
- remove debris and seal off damaged tissue
Microglia
- least abundant
- phagocytes that engulf invading microorganisms and dead neurons
Ependymal cells
- surfaces are covered in cilia that help circulate CSF
Oligodendrocytes
- forming myelin sheaths in the CNS
- do not allow regeneration
Satellite cells
- located in PNS
- supply nutrients and provide structural support
Schwann cells
- create myelin sheaths in the PNS
- allow for regeneration
What is the synapse?
space between neurons, the site at which neurons communicate
Presynaptic neuron
conducts signal toward synapse - releases the NT
Postsynaptic neuron
transmits signal away from synapse - receives the NT
What are the types of synapses?
- axodendritic: btwn axon terminal of one neuron and dendrites of another
- axosomatic: btwn axons and cell bodies
- axoaxonic: btwn axon and axon
- dendrodendritic: btwen dendrite and dendrite
- dendrosomatic: btwn the dendrite and the cell body of another
What is the resting membrane potential? What contributes to this?
- -70 mV
- sodium, potassium, chloride, and negatively charged proteins
What are the two ways that the resting membrane potential is maintained?
- passive - passive diffusion of some ions
- active - sodium potassium pump (3 Na are moved out, and 2 K are moved in)
What are the stages of an action potential?
- local potentials depolarize to threshold (-55mV)
- sodium channels open, Na+ enters the cell, depolarizing it
- sodium channels close, gated potassium channels open, K+ leaves, hyperpolarizing the cell
- all gated channels close, cell returns to resting potential
What is the purpose of an AP?
to release a NT
Absolute refractory period
brief period in which it is impossible to elicit another action potential
Relative refractory period
period in which a higher amount of stimulation is necessary to make a neuron fire
Saltatory conduction
- one node of ranvier depolarizes the next - the AP jumps across them
- more rapid in myelinated
Gray matter
cell bodies, dendrites, unmyelinated axons
White matter
myelinated axons, made up mostly of fat
What are the meninges in order of most superficial to least? What is their function?
- to protect the brain
- dura -> arachnoid -> pia
Ventricles
house CSF, which protects and adds buoyancy to the brain
Spinal cord
- made up of white and gray matter
- relays messages and functions in reflexes
Brain stem, what is it made up of?
- attaches to the spinal cord
- medulla: respiration and HR
- pons: sleep cycles, visual and sensory sensations
- tectum: in midbrain, visual and auditory pathways
- tegmentum: in midbrain, pain pathways
Cerebral cortex
- comprised of fissures and sulci and separated
- important in higher intellectual functioning
Frontal lobe
executive functioning (organization, planning), primary motor cortex is located here, inhibition, production of speech
Parietal lobe
spatial and sensory (primary somatosensory cortex) - touch, feeling, sensation, temperature, pain
Occipital lobe
vision
Temporal lobe
hearing (primary auditory cortex), memory, and comprehension of speech
The entire body is represented spatially in the ______ ______ and ________________ cortex.
primary motor, somatosensory
Lateralization
- certain activities are exclusive to one of the 2 hemispheres
- L hemi: language, math, logic
R hemi: musical, artistic, and other creative endeavors
What structure allows for information to pass btwn both hemispheres of the brain?
corpus callosum
Cerebellum, what can its function be altered by?
- maintains balance and equilibrium, coordinates movements
- drugs like alcohol
Cerebellar ataxia
- damage to the cerebellum
- ataxia caused by disorders of the cerebellum and its afferent and efferent connections
- S/S: unsteadiness, jerky and irregular limb movements, slow speech
Thalamus
- primary sensory relay station, except for smell
- regulates sleep cycle
Thalamic syndrome
- neurological disorder that causes hypersensitivity to pain
- caused by damage to the thalamus
Hypothalamus
- regulates:
- autonomic response (fight or flight)
- emotional response
- body temp.
- food intake
- homones
Basal ganglia
fine motor responses
Limbic system
- amygdala, cingulate gyrus, hippocampus, and nucleus accumbens
- integrates emotional responses, regulates motivated behavior and learning
Amygdala
- regulates fear and anxiety, emotional memory
Hippocampus
- long term memory (transfer of STM to LTM)
- spatial navigation
Depolarization/Excitation
make more positive, brings cell to threshold, causing an action potential
Hyperpolarization/Inhibition
make more negative
