The Nervous System Flashcards
the chemical messengers of the nervous system
Neurotransmitters
the chemical messengers of the endocrine system
Hormones
What 2 things make up the CNS vs the PNS?
CNS = Brain + Spinal Cord
PNS = Spinal Nerves + Cranial Nerves
the basic functional units of the nervous system that respond to stimuli and conduct impulses from one part of the cell to another
Neurons
the cell body of a neuron
Perikaryon (Soma)
neuron extensions involved in afferent processes
Dendrites
neuron extensions involved in efferent processes
Axons (Nerve Fibers)
a sheath of fatty substance that cover axons and works with nodes of Ranvier to enhance the speed of impulse conduction
Myelin Sheath
small gaps in the myelin sheath between adjacent glial cells that work with the myelin to enhance the speed of impulse conduction
Nodes of Ranvier
specialized glial cells whose cell membranes makes up the myelin sheath in the brain and spinal cord
Oligodendrocytes
specialized glial cells that make up the myelin sheath in nerves outside of the brain and spinal cord
Schwann Cells
nervous tissue made up of many myelinated axons
White Matter
nervous tissue made up largely of neuron somas
Grey Matter
neurons that carry signals of touch, taste and sensation to the brain
Sensory Neurons
neurons which carry instructions from the brain to the muscles, causing them to move
Motor Neurons
motor neurons in the peripheral nervous system
Lower Motor Neurons
motor neurons carrying signals that initiate body movement from nuclei in the brain
Upper Motor Neurons
How many types of motor neurons are there and what are they called?
- Upper Motor Neurons
- Lower Motor Neurons
neurons that carry signals between neurons
Interneurons
cells that structurally and functionally support and protect neurons so the neurons can do their jobs as well as outnumber neurons 10:1
Neuroglia (Glial Cells)
conduct nerve impulses toward the CNS
Afferent (Sensory) Nerve Fibers
Afferent vs Efferent
Sensory vs Motor
Afferent > Sensory
Efferent > Motor
conduct nerve impulses away from the CNS
Efferent (Motor) Nerve Fibers
a nerve that contains only afferent nerve fibers
Sensory Nerve
a nerve that contains only efferent nerve fibers
Motor Nerve
nerve fibers that contain both afferent and efferent nerve fibers
Mixed Nerves
What 2 places are mixed nerves found?
- Most nerves in the PNS
- Nerve tracts in the CNS
the system that controls and coordinates voluntary control of skeletal muscles
Somatic Nervous System
nerves that control the voluntary initiation of efferent impulses
Somatic Motor Nerve
nerves that send impulses to the CNS from receptors in the muscles, skin, eyes, or ears that are consciously perceived by the brain
Somatic Sensory Nerve
the system that controls and coordinates the self-regulation of necessary bodily functions
Autonomic Nervous System
nerves that control the involuntary initiation of efferent impulses
Autonomic Motor Nerve
nerves that receive the afferent sensory impulses from sensory receptors used to self-regulate necessary bodily functions
Autonomic Sensory Nerve
Give an example of:
1. Somatic Motor Nerve
2. Somatic Sensory Nerve
3. Autonomic Motor Nerve
4. Autonomic Sensory Nerve
- Somatic Motor Nerve = Animal turning its head in response to owner calling its name
- Somatic Sensory Nerve = Animal feeling you petting them
- Autonomic Motor Nerve = Digestion
- Autonomic Sensory Nerve = The body feeling the stomach stretch to tell the brain to initiate digestion
the state when a neuron is not being stimulated but is still working to maintain this state
Resting State
the difference in electrical charges across a neuron cell membrane in which the inside is more negative than the outside
Resting Membrane Potential
What is the standard resting membrane potential?
-70 mV
the opening of neuron sodium channels that causes a sudden influx of sodium ions into the cell
Depolarization
the significant change in electrical charge within a neuron from negative to positive due to an influx of Na+ ions
Action Potential
the opening of neuron potassium channels that causes a sudden outflux of potassium ions from the cell
Repolarization
Explain the conduction of an action potential in 5 steps
- Cell membrane is polarized (resting state)
- Stimulus changes the membrane potential voltage > Threshold reached
- Nerve impulse is generated > Na+ channels open along the cell membrane of the entire neuron > Na+ passively flow in (depolarization)
- K+ channels open > K+ passively flow out > cell membrane returns to resting potential (repolarization)
- Sodium-Potassium Pump returns the Na+ and K+ to their appropriate sides of the membrane
the membrane potential voltage that must be reached in order to generate a nerve impulse
Threshold
a stimulus of sufficient intensity to generate a nerve impulse
Threshold Stimulus
when an initial stimulus causes a wave of the opening of sodium channels along the cell membrane of the entire neuron
Conduction of the Action Potential (Wave of Depolarization / Nerve Impulse)
the phenomenon in which a complete neuron depolarizes to its maximum strength or it does not depolarize at all
All-or-Nothing Principle
the very brief phase during and after a neuron has generated a nerve impulse and cannot generate another
Refractory Period
the part of the refractory period involving the sodium influx and early potassium outflux in which no stimulus, no matter how strong, can cause the cell to depolarize again
Absolute Refractory Period
the part of the refractory period involving a very strong stimulus arriving during the tail end of the repolarization in which the cell may depolarize again
Relative Refractory Period
the rapid process of conducting an action potential via the depolarization wave in the myelinated axon that skips from one node of Ranvier to the next
Saltatory Conduction
a drug injected into superficial areas of the body to block the conduction of sensations from that area
Local Anesthetic
a local anesthetic molecule that prevents the sensory neuron from depolarizing by clogging and blocking the sodium channels
Lidocaine
the perpetuation of nerve impulse from one neuron to the next cell via the release of a chemical to stimulate the next cell
Synaptic Transmission
the junctions between 2 neurons or a neuron and a target cell
Synapse
the physical gap between the 2 cells
Synaptic Cleft
the neuron bringing the nerve impulse to the synapse and releasing the neurotransmitter to stimulate the next cell
Presynaptic Neuron
the chemical released into the synaptic cleft to stimulate the next cell
Neurotransmitter
a branched structure at the end of the axon of a presynaptic neuron
Telodendron
the enlarged bulb at the end of telodendron containing mitochondria, calcium channels, and vesicles containing neurotransmitters
Synaptic Knob
the neuron containing receptors the receive and bind to the neurotransmitters in order to initiate the impulse
Postsynaptic Neuron
specialized proteins on the postsynaptic membrane that bind to specific neurotransmitters in the synaptic cleft in order to trigger changes in the postsynaptic cell
Receptors
Name the 2 types of neurotransmitters that affect postsynaptic membranes
- Excitatory Neurotransmitters
- Inhibitory Neurotransmitters
neurotransmitters that cause an influx of sodium into the postsynaptic membrane to move the membrane toward threshold and trigger a new nerve impulse
Excitatory Neurotransmitters
neurotransmitters that cause the opening of chloride or potassium channels in order to hyperpolarize the postsynaptic membrane and move the membrane charge away from the required threshold
Inhibitory Neurotransmitters
a catecholamine neurotransmitter associated with arousal and fight-or-flight reactions of the sympathetic nervous system
Norepinephrine
a catecholamine neurotransmitter released primarily from the adrenal medulla and plays more of a role as a hormone in the fight-or-flight reactions of the sympathetic nervous system
Epinephrine
a catecholamine neurotransmitter in the brain involved with autonomic functions and muscle control
Dopamine
an inhibitory neurotransmitter found in the brain
Gamma-aminobutyric Acid (GABA)
a tranquilizer that works to inhibit activity in the brain and producing reduced anxiety with sedation (drowsiness) aka enhancing the GABA effects on the brain
Diazepam (Valium)
an inhibitory neurotransmitter found in the spinal cord
Glycine
a neurotransmitter that can be either excitatory or inhibitory depending on its location in the body
Acetylcholine
a common antiparasitic drug that causes an increased inhibitory neurotransmitter effect
Ivermectin
The stopping and recycling of neurotransmitters are achieved by what?
Enzymes
an enzyme in the postsynaptic membrane that breaks down acetylcholine so the components can be reabsorbed by the synaptic knob, reassembled into new acetylcholine molecules, and repackaged into vesicles for the next depolarization
Acetylcholinesterase
an enzyme in the synaptic knob that breaks down reabsorbed norepinephrine into its components
Monoamine Oxidase (MAO)
an enzyme that breaks down any norepinephrine not reabsorbed into the synaptic knob
catechol-O-methyl transferase (COMT)
the nerve poison found in the skin of poison dart frogs
Curare
What are the 4 sections of the brain?
- Cerebrum
- Cerebellum
- Diencephalon
- Brainstem
the area of the brain that receives and interprets sensory information, initiates conscious nerve impulses to skeletal muscles, and integrates neuron activity associated with higher order behaviors and behaviors associated with conscious activity
Cerebrum
The largest part of the brain
Cerebrum
the most superficial layer of the cerebrum made of grey matter
Cerebral Cortex
the set of fibers that connects the 2 halves of the cerebral cortex made of white matter
Corpus Callosum
the folds of the cerebral cortex
Gyri (sg. Gyrus)
the deep grooves of the cerebral cortex
Fissures
the most prominent groove in cerebral cortex that divides the cerebrum into hemispheres
Longitudinal Fissures
the shallow grooves of the cerebral cortex that divide the cerebral hemispheres into lobes
Sulci (sg. Sulcus)
regions of the cerebral hemispheres that specialize in certain functions
Lobes
a projection of tissue on the rostral and ventral surface of the brain which receives and processes sensory signals from the nose
Olfactory Lobe
the cavity within each hemisphere of the brain where cerebrospinal fluid is produced
Lateral Ventricle
the area of the brain that controls movement coordination, balance, posture, and complex reflexes by using sensory feedback to keep informed on the location of the body and its parts
Cerebellum
the most superficial layer of the cerebellum that consists of grey matter
Cerebellar Cortex
a condition in which voluntary movements become jerky and exaggerated due to a diseased or damaged cerebellum
Hypermetria
What is a clinical sign of hypermetria?
Goose-step gait > lifting and placing of the foot becomes exaggerated
the nervous system passageway between the brainstem and the cerebrum
Diencephalon
the relay station for regulating sensory inputs to the cerebrum
Thalamus
the interface between the nervous system and the endocrine system and plays a major role in temperature regulation, hunger, thirst, and components of anger responses
Hypothalamus
the endocrine gland that regulates production and release of hormones throughout the body
Pituitary Gland
the connection between the rest of the brain and the spinal cord that is heavily involved in autonomic control functions of the body
Brainstem
List the 3 components of the brainstem
- Medulla Oblongata
- Pons
- Midbrain
The brainstem is involved in what 5 autonomic control functions?
- HR
- Respiration
- Vasomotor Control
- Swallowing
- Vomiting
blood vessel diameter control
Vasomotor Control
the 3 vascular connective tissue layers that surround the brain and spinal cord
Meninges
What are the 3 meningeal layers?
- Dura Mater
- Arachnoid
- Pia Material
the tough, fibrous and outermost meningeal layer
Dura Mater
the delicate, web-like meningeal layer
Arachnoid
the thin meningeal layer directly on the surface of the brain and spinal cord
Pia Mater
the area between the dura mater and the arachnoid meninges composed of fluid, fat, and connective tissue that provide some cushioning
Subdural Space
the area between the arachnoid and pia mater meninges composed of fluid, fat, and connective tissue that provide some cushioning
Subarachnoid Space
the inflammation of the connective tissue layers surrounding the brain and spinal cord that typically result from viral or bacterial infection
Meningitis
the clear, slippery fluid circulating between layers of the meninges, through brain ventricles, and through the spinal cord central canal that function to protect these structures
Cerebrospinal Fluid
the process used to take a sample of CSF in order to examine it for particular types of cells or specific changes in composition and diagnose certain nervous system diseases or cancers
CSF Tap
the functional barricade separating the capillaries in the brain from the nervous tissue itself to protect the brain from poisons circulating in the bloodstream
Blood-Brain Barrier
the openings between the cells of capillary walls except those capillaries found in the brain
Fenestrations
a special set of 12 nerves in the PNS that originate directly from the brain that may contain axons of motor neurons, axons of sensory neurons, or combinations of both
Cranial Nerves
How many cranial nerves are there?
12
List the 12 cranial nerves
- Olfactory
- Optic
- Oculomotor
- Trochlear
- Trigeminal
- Abducent
- Facial
- Vestibulocochlear
- Glossopharyngeal
- Vagus
- Accessory
- Hypoglossal
Name the 4 cranial nerves that are both sensory and motor
- Trigeminal
- Facial
- Glossopharyngeal
- Vagus
List the types (sensory, motor, or both) of the following cranial nerves:
1. Olfactory
2. Optic
3. Oculomotor
4. Trochlear
5. Trigeminal
6. Abducent
7. Facial
8. Vestibulocochlear
9. Glossopharyngeal
10. Vagus
11. Accessory
12. Hypoglossal
- Olfactory - sensory
- Optic - sensory
- Oculomotor - motor
- Trochlear - motor
- Trigeminal - both
- Abducent - motor
- Facial - both
- Vestibulocochlear - sensory
- Glossopharyngeal - both
- Vagus - both
- Accessory - motor
- Hypoglossal motor
Cranial nerve involved with smell
Olfactory
Cranial nerve involved with vision
Optic
Cranial nerve involved with eye movement, pupil size, focusing the lens
Oculomotor
Cranial nerves involved with eye movement
- Oculomotor
- Trochlear
- Abducent
Cranial nerve involved with chewing and sensations from the head and teeth
Trigeminal
Cranial nerve involved with taste, tears, salivation, and face and scalp movement
Facial
Cranial nerve involved with balance and hearing
Vestibulocochlear
Cranial nerve involved with tongue movement, swallowing, salivation, and taste
Glossopharyngeal
Cranial nerve involved with sensations from the GI tract and respiratory tree and movement of the larynx, pharynx, PaSNS organs, abdominal organs and thoracic organs
Vagus
Cranial nerve involved with head movement and support movement with the Vagus nerve
Accessory
Cranial nerve involved with tongue movement
Hypoglossal
Cranial nerves involved with taste and salivation
- Facial
- Glossopharyngeal
Cranial nerves involved with tongue movement
- Glossopharyngeal
- Hypoglossal
the caudal continuation of the brainstem outside the skull that conducts sensory information and motor instructions between the brain and the periphery of the body
Spinal Cord
the innermost part of the spinal cord consisting of grey matter through which the central canal runs
Medulla
the passageway in the middle of the medulla that runs the length of the spinal and contains cerebrospinal fluid
Central Canal
the outermost layer of the spinal cord made of white matter
Spinal Cortex
located between each pair of adjacent vertebrae that link the spinal cord to peripheral nerves and contain afferent nerve fibers
Dorsal Nerve Roots
located between each pair of adjacent vertebrae that link the spinal cord to peripheral nerves and contain efferent nerve fibers
Ventral Nerve Roots
the region of the spinal cord’s grey matter butterfly where the neurons that process and carry afferent nerve impulses to the brain or other parts of the spinal cord are located
Dorsal Horns
the region of the spinal cord’s grey matter butterfly where the neurons that process and carry efferent nerve impulses to spinal nerves are located
Ventral Horns
the spinal nerve found medial to the scapula on each side of the body that is involved with controlling the thoracic limbs, and is formed from the fusion of the ventral branches of several spinal nerves
Brachial Plexus
List the 4 nerves that exit the brachial plexus
- Axillary Nerve
- Radial Nerve
- Median Nerve
- Ulnar Nerve
the nerve exiting the brachial plexus that supplies the muscles that flex the shoulder and the skin over the cranial surface of the elbow
Axillary Nerve
the nerve exiting the brachial plexus that supplies the lateral surface of the humerus and the cranial-lateral surface of the foreleg and foot
Radial Nerve
the nerve exiting the brachial plexus that supplies the medial surface of the foreleg and the palmar surface of the foot
Median Nerve
the nerve exiting the brachial plexus that supplies the caudal surface of the foreleg and palmar surface of the foot
Ulnar Nerve
the spinal nerve involved with controlling the pelvic limbs
Lumbosacral Plexus
List the 3 nerves that exit the lumbosacral plexus
- Femoral Nerve
- Obturator Nerve
- Ischiatic (Sciatic) Nerve
the nerve exiting the lumbosacral plexus that supplies the cranial muscles of the femur and sensory nerves to the medial surface of the thigh and hindlimb
Femoral Nerve
the nerve exiting the lumbosacral plexus that supplies primarily the muscles of the medial thigh
Obturator Nerve
the nerve exiting the lumbosacral plexus that passes over the hip joint and travels down the caudal-lateral surface of the thigh to supply the caudal thigh muscles
Ischiatic (Sciatic Nerve)
the introduction of anesthetic drugs into the space between the spinal cord dura mater and the surrounding bone
Epidural Anesthesia
a contrast radiography procedure involving the injection of radiopaque dye into the spinal cord subarachnoid space to identify the existence of a ruptured disc
Myelography
What are the 2 divisions of the autonomic nervous system?
- Sympathetic Nervous System
- Parasympathetic Nervous System
the division of the autonomic nervous system that helps the body cope with emergency situations
Sympathetic Nervous System
the division of the autonomic nervous system that brings the body back to its resting state and facilitates all the processes that will replace body resources used up during an emergency
Parasympathetic Nervous System
Name 2 neurotransmitters of the sympathetic nervous system
- Norepinephrine
- Epinephrine
What type of neurons secrete the neurotransmitters of the sympathetic nervous system?
Adrenergic Neurons
Name a neurotransmitter of the parasympathetic nervous system
Acetylcholine
Name 3 adrenergic receptors of the sympathetic nervous system
- Alpha1-adrenergic receptors
- Beta1-adrenergic receptors
- Beta2-adrenergic receptors
receptors associated with the sympathetic nervous system that cause vasoconstriction of the skin, GI tract, kidney
Alpha1-adrenergic receptors
receptors associated with the sympathetic nervous system that increase the heart rate and force of contraction
Beta1-adrenergic receptors
receptors associated with the sympathetic nervous system that cause bronchodilation
Beta2-adrenergic receptors
Name 2 cholinergic receptors of the parasympathetic nervous system
- Nicotinic Receptors
- Muscarinic Receptors
receptors found primarily on the postganglionic neurons of both the sympathetic and parasympathetic nervous system, as well as between motor neurons and muscles in the somatic motor system
Nicotinic Receptors
receptors found on the target organs and tissues supplies by the postganglionic neurons of the parasympathetic nervous system
Muscarinic Receptors
a rapid, automatic response to stimuli designed to protect the body and maintain homeostasis
Reflex
List the 2 types of reflexes
- Somatic
- Autonomic
reflexes that involve contraction of skeletal muscles
Somatic Reflexes
List the 2 types of somatic reflexes
- Contralateral Reflexes
- Ipsilateral Reflexes
reflexes that start on one side and travel to the opposite side of the body
Contralateral Reflexes
reflexes in which the stimulus and the response are on the same side of the body
Ipsilateral Reflexes
reflexes that regulate smooth muscle, cardiac muscle, and endocrine glands
Autonomic Reflexes
the nerve pathway involved in a reflex action
Reflex Arc
Name 3 somatic reflexes commonly evaluated in vet medicine
- Stretch Reflex
- Withdrawal Reflex
- Crossed Extensor Reflex
the ipsilateral reflex that results in the contraction of a muscle that occurs in response to its stretch
Stretch Reflex
the sensory receptor in the stretch reflex arc
Muscle Spindle
the multisynaptic reflex arc that results in the rapid removal of a limb or flexion of a joint after touching a painful stimulus
Withdrawal Reflex
the contralateral reflex in which the afferent sensory impulse crosses to the other side of the spinal cord and stimulates the muscles that extend the opposite limb
Crossed Extensor Reflex
a reaction when a muscle contracts with more force and produce more limb movement that normal
Hyperreflexive
a reaction when a muscle contracts with less force or produces no movement altogether
Hyporeflexive
a reflex that produces a blink of the eyelids when the medial canthus of the eye is tapped
Palpebral Reflex
Reflexes are routinely tested in clinical settings. Name 2
- Assessing an animal for depth of anesthesia
- Performing a physical exam
a reflex that produces the constriction of both pupils when light shines in one or both of the animal’s eyes to protect the retina by reducing the amount of light entering
Pupillary Light Reflex