Exam 3 by alexis_harrison180

Central Nervous System (CNS)

-consists of the brain and spinal cord

-controls our thoughts, movements, emotions, and desires

-controls breathing, heart rate, release of some hormones, body temperature, etc.

Peripheral Nervous System (PNS)

-consists of cranial and spinal nerves

-plays a key role in both sending information from different areas of the body back to the brain, as well as carrying out commands from the brain to various parts of the body

PNS two main subsystems:

Autonomic and somatic

autonomic nervous system (ANS)

-the part of the peripheral nervous system that controls the glands and the muscles of the internal organs (such as the heart).

-involuntary

-Its sympathetic division arouses; its parasympathetic division calms.

-Controls functions such as heart rate, blood pressure, respiration, digestion, and sexual arousal

-Consists of visceral motor nerve fibers

-Preganglionic fibers release ACh

-Postganglionic fibers release norepinephrine or ACh at effectors

-Effect is either stimulatory or inhibitory, depending on type of receptors

Somatic Nervous System (SNS)

-The division of the peripheral nervous system that controls the skeletal muscles and transmits sensory information.

-voluntary

-All somatic motor neurons release acetylcholine (ACh)

-Effect is always stimulatory

Sensory (afferent) division

-Division of the PNS that carries impulses/information from peripheral organs to the CNS

Motor (efferent) division

-transmits impulses from the CNS to the peripheral organs to cause an effect or action

sympathetic nervous system

-activates the fight-or-flight response during a threat or perceived danger

-Shunts blood to skeletal muscles and heart

-Dilates bronchioles

-Causes liver to release glucose

parasympathetic nervous system

-a set of nerves that help the body return to a normal resting state, calming the body

divisions of autonomic nervous system

sympathetic and parasympathetic

somatic sensory fibers

convey impulses from skin, skeletal muscles, and joints to CNS

visceral sensory fibers

convey impulses from visceral organs to CNS

Ganglia

clusters of cell bodies in the PNS

Cranial Nerve I: Olfactory

-sense of smell

-sensory function

Cranial Nerve II: Optic

-vision

-sensory function

Cranial Nerve III: Oculomotor

-innervates four of the extrinsic eye muscles

-Passes through the superior orbital fissure to enter the orbit.

-Function in raising eyelid, directing eyeball, constricting iris (parasympathetic), and controlling lens shape

-Damage results in double vision, drooping of the eye laterally

-Motor function

Cranial Nerve IV: Trochlear

- Primarily motor nerve that directs eyeball -"moves down and out"

-damage results in double vision

-Motor function

Cranial Nerve V: Trigeminal

-chewing, smiling

-Damage results in brain freeze sensation, overstimulated facial sensations and pain

-Both sensory and motor function

Cranial Nerve VI: Abducens

-innervates the lateral rectus muscle (abducts eye)

-damage results in double vison

-Motor function

Cranial Nerve VII: Facial

-facial expression; taste - anterior 2/3 of tongue; eyelid and lip closure

-Damage results in loss of taste and dryness of mouth

-Both sensory and motor function

Cranial Nerve VIII: Vestibulocochlear

-sensory, hearing, and balance

-Afferent fibers from hearing receptors (cochlear division) and equilibrium receptors (vestibular division) pass from inner ear through internal acoustic meatuses and enter brain stem at pons-medulla border

-Damage results in lack of balance and relationship to horizon

-Sensory function for hearing and balance, some motor function for sensitivity of sensory receptors

Cranial Nerve IX: Glossopharyngeal

-gagging; swallowing, taste

-fibers emerge from medulla oblongata and run through throat

-Damage results in dryness of mouth, difficulty swallowing, loss of taste

- Sensory functions: taste

- Motor functions: swallowing and salivary glands

Cranial Nerve X: Vagus

-Only nerves that extend to thorax and abdomen to visceral organs

-Sensory fibers carry impulses to thorax and abdomen for blood pressure, respiration, and taste

-Motor fibers are parasympathetic, supply heart, lungs, regulate heart rate, breathing, and digestive system activity

-known as "wanderer"; damage results in difficulty swallowing, stomach aches, loss of taste.

-Sensory and motor function

Cranial Nerve XI: Accessory

-shoulder movement and head rotation

-Damage results in head deviating to one side

-Motor function

Cranial Nerve XII: Hypoglossal

-Innervate extrinsic and intrinsic muscles of tongue that contribute to swallowing and speech

-Motor Function

Astrocytes

- Most abundant, versatile, and highly branched of glial cells

- Cling to neurons, synaptic endings, and capillaries

-Support and brace neurons

-Play role in exchanges between capillaries and neurons

-Guide migration of young neurons

-Control chemical environment around neurons -Respond to nerve impulses and neurotransmitters

-Participate in information processing in brain

Oligodendrocytes

-Type of glial cell in the CNS that wrap axons in a myelin sheath.

Satellite cells (PNS)

-Surround neuron cell bodies in PNS

-Function similar to astrocytes of CNS

-Provide nutrients and structural support for neurons in the PNS

Schwann cells

-Supporting cells of the peripheral nervous system responsible for the formation of myelin.

resting membrane potential

-Membrane is polarized

-All channels are closed

Depolarization

-The process during the action potential when sodium is rushing into the cell causing the interior to become more positive.

Repolarization

-Return of the cell to resting state, caused by reentry of potassium into the cell while sodium exits the cell.

Hyperpolarization

Inside of the cell membrane becomes more negative than it was at resting due to potassium exiting the cell.

Thalamus

-the brain's sensory switchboard, located on top of the brainstem; it directs messages to the sensory receiving areas in the cortex and transmits replies to the cerebellum and medulla

-All information from the body's senses (besides smell) must be processed through the thalamus before being sent to the brain's cerebral cortex for interpretation

-plays a role in sleep, wakefulness, consciousness, learning, and memory

Hypothalamus

-A neural structure lying below the thalamus; it directs several maintenance activities (eating, drinking, body temperature), helps govern the endocrine system via the pituitary gland, and is linked to emotion and reward.

-Forms cap over brain stem and forms inferolateral walls of third ventricle

-Contains many important nuclei such as: - Mammillary bodies: paired anterior nuclei that act as olfactory relay stations

-Infundibulum: stalk that connects to pituitary gland

- Controls autonomic nervous system

epithalmus

-Most dorsal portion of the diencephalon

-Forms roof of the third ventricle

-Contains pineal gland (body)

- Extends from the posterior border

- Secretes melatonin that helps regulate the sleep-wake cycle

Midbrain

-A small part of the brain above the pons that integrates sensory information and relays it upward.