A & P Exam 3

What are the 3 basic functions of the nervous system?

-Sensory input

-Integration

-Motor output

What are the 2 main divisions of the nervous system?

Central nervous system → brain & spinal cord

Peripheral nervous system → peripheral nerves

What are the two divisions of the peripheral nervous system?

Somatic nervous system → really info between skin, skeletal muscle, & CNS, consciously control pathways

Autonomic nervous system → relay info between organs & CNS, involuntary control

What are the two divisions of the autonomic nervous system?

Sympathetic → “fight or flight”

Parasympathetic → “rest & digest”

What is a neuron?

The structural & functional unit of the nervous system, functions to recieve and send signals throughout the body. Contains dendrites, a soma, an axon, a myelin sheath, and nodes of rancher

What are sensory (afferent) neurons?

Carry info from sensory receptors TO the CNS

What are motor (efferent) neurons?

Carry info FROM CNS to systems

What are interneurons?

Connect sensory and motor neurons

What are oligodendrocytes?

Myelinate the CNS axons, provide structural framework

What are astrocytes?

Glia that maintain the blood-brain barrier, provide structural support, regulate ions, nutrients, & dissolved gas, recycle neurotransmitters

What are microglia?

Glial cells that remove cell debris, wastes, and pathogens by phagocytosis

What are ependymal cells?

Line ventricles & central canal, assist in producing cerebrospinal fluid

What are satellite cells?

Surround neuron cell bodies in PNS, regulate nutrient and transmitter levels

What are Schwann cells?

Myelinate peripheral axons

What is the difference between a nerve and a tract?

Nerve is a bundle of axons in the PNS, tract is a bundle of axons in the CNS

What is the difference between a nucleus and a ganglion?

Nucleus is a cluster of cell bodies within the CNS, ganglion is a cluster of cell bodies within the PNS

What is the importance of the myelin sheath?

Insulates the axon, increases saltutory conduction, speeding up the action potentials

What is the process of an action potential?

At rest, high Na+ outside, high K+ inside, around -60mV

Depolarization → Na+ channels open, membrane potential rises

Overshoot → membrane potential gets wry high, Na+ begins to inactivate

Repolarization → membrane potential begins to drop, K+ channels open and Na+ channels are inactivated

Undershoot → membrane becomes more negative than resting

Back to resting potential

What is a synapse?

Specialized junction where neurons communicate with other cells

What’s the difference between electrical and chemical synapses?

Electrical → 2 neurons physically connected by gap junctions, single transmission is instantaneous, relies on direct flow of electrical current

Chemical → neurons are separated by a synaptic cleft, communicate between neurotransmitters through the release of them into the cleft

What are neurotransmitters?

Chemicals that allow neurons to communicate across synapses by binding to receptors

Classified by molecular structure (amino acids, amines, peptides)

Classified by functional effects (excitatory, inhibitory, modulatory)

What is the neural tube?

Structure in embryonic development taht becomes that brain & spinal cord, formed when the neural plate folds, creating a groove then fuses to form the tube

What is the prosencephalon?

The forebrain, becomes the telencephalon and diencephalon

What is the mesencephalon?

The midbrain, becomes the mesencephalon

What is the rhombencephalon?

The hindbrain, becomes the metencephalon and the myelencephalon

What does the telencephalon become?

The cerebrum and lateral ventricle

What does the diencephalon become?

The thalamus, hypothalamus, and 3rd ventricle

What does the mesencephalon become?

The brain stem, midbrain, and cerebral aqueduct

What does the metencephalon become?

The pons, cerebellum, and 4th ventricle

What does the myelencephalon become?

The medulla and 4th ventricle

What is gray matter?

Composed mostly of cell bodies, outer layers of brain

What is white matter?

Composed of fiber tracts within gray matter

What are projection fibers?

Cerebral cortex w lower levels of spinal cord

What are association fibers?

Connect 2 areas of cerebral cortex on the same side of brain

What are commissural fibers?

Connect same cortical regions on 2 sides of brain (corpus collosum)

What is the basal nuclei?

Internal island of gray matter

What is the frontal lobe?

Responsible for executive skills and higher thinking. Contains prefrontal association areas, premotor cortex, and primary motor cortex

What is the parietal lobe?

Contains the primary somatosensory cortex and the sensory association areas

What is the occipital lobe?

Contains the visual association areas and primary visual cortex

What is the temporal lobe?

Contains the primary auditory cortex, auditory association areas, olfactory cortex, and limbic association cortex

What is the limbic system?

Contains the olfactory bulbs, mamillary bodies, amygdala, hippocampus, fornix, and cingualte gyrus. Responsible for learning, emotion, and behavior

What is short term memory?

Working memory, closed neural circuit stimulated over and over, when stimulation ends the memory does too unless consolidated, limited to around 7 bits of info

What is long term memory?

Changes the structure/function of neurons, enhances synaptic transmission

What is the thalamus?

Relay station for sensory impulses, transfers to cortex

What is the hypothalamus?

Autonomic nervous system center, regulates homeostasis, control emotions, attached to pituitary galnd

What is the epithalamus?

Forms roof of 3rd ventricle, houses pineal body and includes the choroid plexus, making CSF

What is the midbrain?

Contains fibers that join lower parts of brainstem and spinal cord with higher parts of brain, contains cerebral aqueduct, cerebral penduncle and corps quadrigemina

What is the pons?

Underside of brain stem, helps regulate breathing, relays impulses to and from medulla & cerebellum

What is the medulla oblongata?

Enlarged continuation of spinal cord, contains cardiac, vasomotor & respiratory control centers and various non vital reflex centers

What is the reticular formation?

Complex network of nerve fibers throughout brain stem filters incoming sensory info and arouses cerebral cortex to wakefulness

What are the 3 meninges superficial to deep?

Outside

-dura mater

-arachnoid mater

-pia mater

Brain

What is cerebral spinal fluid?

Similar to blood plasma, formed by choroid plexus, forms watery cushion to protect brain, recycled throughout day, travels in the ventricles

What is the spinal cord?

Cylinder of nerve tissue continuous with brain, surrounded by verterbral column and meninges, exterior contains white matter and conduction tracts, interior contains gray matter, cell bodies making up dorsal and ventral horns

What is a traumatic brain injury?

Insult to brain caused by an external physical force

What is a diffuse axonal injury?

Tearing/shearing of microscopic brain cells

What is an acquired brain injury?

Insult to brain that occurred after birth, can include TBI, stroke, infections, anoxia

What is a cerebrovascular accident? (Stroke)

Result of ruptured blood vessel supplying a region causing tissue death and loss of function. Causes severe headache, vision changes, dizziness, confusion, numbness. Can be ischemic (clot) or hemorrhagic (bleed)

What is Alzheimer’s disease?

Progressive degenerative brain disease caused by structural changes in protein deposits and twisted neuron fibers. Causes memory loss, irritability, confusion, and hallucinations

How are sensory receptors classified?

Through the type of stimuli required to activate them. Ex; photoreceptors-light, mechanoreceptors-movement

What are the general senses?

Senses within the skin, temperature, pressure, touch, pain, vibration, proprioception

What are uncapsulated nerve endings?

Free, no capsules on the ends. Includes free nerve endings (pain and temp), Markel’s discs (light touch and pressure), and root hair plexus (light touch)

What are encapsulated nerve endings?

Nerves with a capsule, included pacinian corpuscles (deep pressure), messinels corpuscles (discriminative touch), Krause end bulbs (discriminative touch ion mucous membranes), and ruffinins corpuscles (deep pressure)

What is olfaction?

Sense of smell, comes from chemoreceptors located in the olfactory epithelium, stiumulated by chemicals within the nasal passage, creating a sensation from both chemical perception and data processing within the olfactory bulb. Info goes to olfactory cortex then the limbic system

What is gustation?

Sense of taste, arises from taste buds within the tongue that have papillae that act as chemoreceptors, info travels into the brain through cranial nerves 7 & 9 to the medulla

What are the parts of the ear?

• outer ear → flabby stuff

• Middle ear → canal, ending with tympanic membrane that connects with the ossicles transferring vibration onto the oval window. Also contains the auditory tube, connecting middle ear to throat and only opens to equalize pressure during yawning/swallowing

• Inner ear → contains the organ of corti, vestibule, and semicircular canals, where sound is transduced into chemical signals and balance signals are created

What does the organ of corti do?

Inside the cochlea, contains hair cell receptors that are bent by vibrations traveling down the tectorial membrane, transmitting nerve impulses to the auditory cortex

What does the vestibule within the ear do?

Contains maculae where otoliths float in a gel where movement causes hair ells to bend, sending info via the vestibular nerve about head positioning

What do the semicircular canals do?

Tuft of hair cells covered by cunula, moved by the flow of endolymph, sending signals to the cerebellum vis the vestibular nerve about orientation

What are the 3 tunics that surround the eye?

• fibrous tunic → sclera & cornea

• Choroid tunic → cilliary muscles and iris

• Sensory tunic → the retina

How is light transduced into electrical signals?

Light enters the eye thorugh the pupil, is bent by the lens into focus onto the retina where it hits photoreceptor cells (rods & cones) that pass info to bipolar neurons and then ganglion cells which send into out of the eye via the optic nerve

What is the difference between rods and cones?

• Rods → found around edges of eyes, allow dim light vision & peripheral vision, only perceives gray tones

• Cones → densest in the center of the retina, allow for detailed color vision, have 3 diff kinds sensitive to different wavelengths of light

What is the lacrimal apparatus?

Contains lacrimal fluid (tears) made of a dilute salt solution that functions to protect and moisten the eyes, produced by lacrimal glands, drained from lacrimal canals, and emptied into the nasal cavity through lacrimal sacs and ducts

What are meibomian glands?

Modified sebaceous glands the provide and oily secretion, lubricating the eye

What are ciliary glands?

Modified sweat glands between eyelashes

What are conjunctives?

The membrane lining the eyelids, connected to surface of eye, secretes mucus

What are special somatic afferent fibers?

Carry sensory impulses to brain from receptors of sight, hearing, and equilibrium

What are special visceral afferent fibers?

Carry sensory impulses to brain from olfactory and tast receptors

What are special somatic efferent fibers?

Carry motor impulses from brain to muscles for swallowing, speaking, and facial expressions

What are general visceral efferent fibers?

Carry motor impulses from CNS to smooth muscles and glands

What is the peripheral nervous system?

Nerves and ganglia outside of the cns, contains neuron fibers, cranial nerves, and spinal nerves

How are nerves classified?

Sensory nerves (send info TO brain)

Motor nerves (sends info AWAY from brain)

Mixed nerves (do both)

What is the first cranial nerve?

Olfactory nerve; sensory nerve for smell

What is the second cranial nerve?

Optic nerve; sensory nerve of vision

What is the third cranial nerve?

Oculomotor; innervates extrinsic eye muscles

What is the fourth cranial nerve?

Trochlear; innervates superior oblique muscle

What is the fifth cranial nerve?

Sensory innervation to face, motor innervaition of chewing muscles

What is the sixth cranial nerve?

Abdunces; abducts eyeball, innervates lateral Rectus in eye

What is the seventh cranial nerve?

Facial nerve; innervates facial expressions

What’s is the eight cranial nerves?

Vestibulocochlear; sensory nerve of hearing and balance

What is the ninth cranial nerve?

Glossopharyngeal; innervates tongue and pharynx

What is the tenth cranial nerve?

Vagus; mixed nerve, widespread through thorax nd abdomen

What is the eleventh cranial nerve?

Accessory nerve; innervates the trapezius

What is the twelvth cranial nerve?

Hypoglossal; innervates tongue muscles

What are the spinal nerves?

Contains 31 pairs, formed by a combo of ventral and dorsal roots of the spinal cord

What is the cervical plexus?

Branch of nerve fibers deep in neck, formed by ventral rami C1-C4, mostly cutaneous, some innervates muscles of anterior neck

What is the brachial plexus?

Lies in neck and axilla, formed by C5-C8, main nerves of upper limbs

What is the lumbar plexus?

Arises from L1-L4, small branches innervates posterior abdominal wall & psoas, main branches innervates anterior thigh

What is the sacral plexus?

Arises from L4-S4, rest of lower limb nerves

What are the components of a reflex arc

Receptor → sensory neuron → interneurons of spinal cord → motor neuron → effector