Exam 3 Flashcards
What is the functional unit of the nervous unit of the nervous system
The neuron
What are the parts of the neuron
The perikaryon (soma/body), dendrites, axon, and the axon terminal
What is the function of the dendrites
The afferent process that receives signals from other neurons
What is the function of the axon
The efferent process that synapses w/ another neuron or effector cell
What is synapse
The small gap btw 2 neuron cells where electrical or chemical reaction occurs
What is the pre synaptic cell
The cell prior to the synapse
What is the post synaptic cell
Cell after the synapse
What are characteristics of neurons
High O requirement, only uses glucose for energy, lack repro ability, can regenerate if the cell body is intact, and supported by glial cells
What are astrocytes
Glial cells that maintain the blood brain barrier, levels of neurotransmitter around synapses, regulates ions, and provides metabolic support
What are ependymal cells
Glial cells that line spinal cord and ventricles of the brain and produce CSF
What are oligodendrocytes
Glial cells that myelinate CNS axons and provide structural framework
What are microglia
Glial cells that form the brains immune cells removing dead cells and pathogens via phagocytosis
What are satellite cells
Glial cells that surround neuron cell bodies in ganglia of PNS regulating neurotransmitter levels
What are schwann cells
Glial cells that myelinate neurons in PNS, maintain, and regenerate neurons after injury
What is white brain matter
Lots of myelinated fibers
What is grey brain matter
Lots of neuron cell bodies
What are nodes of ranvier
Gaps in myeline sheath that is vital for accomplishing action potentials by enhancing conduction of nerve impulses
What are afferent nerve fibers
Sensory nerves fibers that send impulses from periphery to CNS
What are efferent nerve fibers
Motor nerve fibers that send impulses from CNS to periphery
What are mixed nerves
Nerves that have both sensory and motor functions primarily found in PNS
What is the autonomic nervous system
Automatic control of smooth muscle, cardiac muscle, and glands allowing afferent activity in terms of autonomic sensory function and efferent activity in terms of autonomic motor function
What is the somatic nervous system
Conscious control of skeletal muscle w/ afferent activities such as somatic sensory function such as muscles, skin, eyes, and ears and efferent w/ somatic motor function
What are the 3 states of a neuron
Resting, depolarization, and repolarization
What is the resting state
The cell membrane working to maintain electrical polarization using the sodium potassium pump and concentration gradients making it more negatively charged inside the cell
What is depolarization
When an action potential causes a sudden influx of Na where the stimulus occurs causing loss of membrane potential this occurs via passive diffusion
What is repolarization
When the Na channels shut, K channels open, passive diffusion occurs, the membrane potential shifs back toward the negative polarized state, and the sodium potassium pump takes over placing the K and Na back on the right side of the membrane
What is the depolarization threshold
The membrane potential that must be reached in order for an action potential to occur
What is an action potential
Wave of depolarization down the cell membrane
What is the all or nothing principle
Neuron completely depolarizes or not at all
What is the refractory period
Insensitive to new stimuli and can be absolute or relative
What is the absolute refractory period
Period of sodium influx and early potassium outflux keeping the cell cannot respond at all no matter how strong the stimulus is
What is relative refractory period
A strong stimulus at the end of repolarization may result in a new action potential
How do myelin sheaths cause conduction
The myelin sheath prevents sodium from crossing the cell membrane allowing the rapid conduction of the action potential to leap down the axon
What is the flow of the synapse down a pre synaptic neuron action potential
Axon, telodendron, and synaptic knob
What happens once the action potential hits the synaptic knob
Ca influxes, a neurotransmitter releases, they bind to receptors on the post synaptic neuron, and the synaptic transmission occurs
What are excitatory neurotransmitters
They open Na channels to depolarize the post-synaptic membrane causing an action potential
What are inhibitory neurotransmitters
Open Cl or K channels that hyperpolarize postsynaptic membrane preventing an action potential
What type of neurotransmitter is acetylcholine
Excitatory by stimulating skeletal and smooth muscle contraction and inhibitory by inhibiting cardiac muscle via parasympathetic nerves slowing HR
What type of neurotransmitter is epinephrine
Excitatory causing the fight or flight response in the sympathetic nervous system
How is epinephrine a hormone and neurotransmitter
Because it is also produced by the adrenal medulla as adrenaline along w/ the sympathetic nervous system
What type of neurotransmitter is norepinephrine
Excitatory as it is an arousal fight or flight response in the sympathetic nervous system
What type of neurotransmitter is dopamine
Excitatory as it stimulates the secretion of GH and inhibitory as it inhibits unnecessary movements and certain hormone secretion from the pituitary gland
What disease is associated w/ a decrease in dopamine neurons
Parkinson’s
What type of neurotransmitter is Gamma Aminobutyric Acid (GABA)
Inhibitory as it reduces neuronal excitability such as seizures
What type of neurotransmitter is glycine
Inhibitory by reducing neuronal excitability
What stops the acetylcholine signal
Acetylcholinesterase breaks down acetylcholine the products are reabsorbed by synaptic knob are reassembled and wait for next action potential in vesicles
What happens if acetylcholinesterase is inhibited
There will be a persistent stimulation of receptors causing salivation, diarrhea, vomiting, dyspnea, miosis, muscle fasciculations, and seizures
How is the norepinephrine signal stopped
At a slower process than stopping acetylcholine and occurs after the release into synaptic cleft and is reabsorbed by synaptic knob broken down by monoamine oxidase (MAO) if any is not reabsorbed in the synaptic knob it is broken down by catchol-O-methyl transferase (COMT)
What is contained in the CNS
Neuron cell bodies, myelinated, unmyelinated nerve fibers, and glial cells
What are the parts of the brain
Cerebrum, cerebellum, diencephalon, brainstem, meninges, cerebrospinal fluid, blood brain barrier, and cranial nerves
What is the cerebrum
The largest part of the brain in domestic animals, area of learning and intelligence, the gyri is separated by fissues and sulci, where sensory info is received and interpreted, voluntary motor control is initiated here, and integration of neuron info such as emotional response, learning, memory, and recall
What divides the cerebrum into 2 hemipheres
The longitudinal fissure
What is the function of the corpus callosum in the cerebrum
Allows for communication btw the left and right hemipheres
What does the sulci do
Divides the hemispheres into lobes superficially
What are the different lobes of the brain
Frontal, parietal, occipital, and temporal
What is the cerebellum
Second largest part, contains grey matter cortex w/ white matter underneath, coordinates movement, balance, posture, and complex reflexes, and results in hypermetria if damage/disease which is exaggerated movements
What is the diencephalon
Passageway btw cerebrum and brainstem and contains the thalamus, hypothalamus, and pituitary
What is the function of the thalmus
Regulates the sensory input to the cerebrum
What is the function of the hypothalamus
Nervous system-endocrine system interface w/ temperature control, thirst, hunger, and anger response
What is the pituitary
Master gland of the endocrine system
What is the brainstem
The connection btw the spinal cord and the rest of the brain, it is the most primitive part for autonomic control of the cardiovascular system, respiration, swallowing, and vomiting, and contains the medulla oblongota, pons, and midbrain
What are the meninges
Connective tissue layers surrounding the brain/spinal cord supplying nutrient, oxygen, and cushioning, the layers are the dura mater, arachnod, and pia mater
What is dura mater
Tough and fibrous superficial layer of the meninges
What is the arachnoid
Delicate spider web looking layer that contains CSF
What is the pia mater
Thin layer that lies on the brain/spinal cord