PSIO 201 Lab Practical 4.1 - some of 4.3

Oligodendrocytes

Forms myelin sheath in CNS

Astrocytes

• Maintains environment around neurons

• Keeps neurons in place

• Forms the blood brain barrier

Microglia

engulfs (eats) invading microbes, debris, and necrotic tissue

Ependymal cells

• Line the 4 ventricles of the brain and central canal

• Facilitate circulation of CSF

Schwann cells

Entire cell forms the myelin sheath around a segment of the axon in PNS

Satellite cells

• Covers sensory/afferent neuron cell bodies

• Maintain neuron chemical environment

Multiple sclerosis

Causes damages to myelin sheaths surrounding nerve fibers and nerve fibers themselves

Medulla Oblongata

• Heart rate

• blood pressure

• **respiratory rate

• coughing/sneezing/swallowing/vomiting reflexes

Pons

Respiratory depth

Midbrain

Contains superior/inferior colliculus

Superior colliculus

Visual reflex center

Inferior colliculus

Auditory/startle reflex

Cerebellum

• Posture and balance

• Contains vermis, folia, and arbor vitae

Thalamus

• Relay station (sensory processing)

• Assc. w/ the third ventricle

• Regulation of emotion, memory, motor activity

• Contains intermediate mass

Epithalamus

Contains pineal gland (secretes melatonin)

Hypothalamus

• Manages body’s homeostasis, body temp, sleep-wake cycle

• Contains mammillary bodies (smell/taste), optic chiasm (where optic nerves cross, visual info gets processed by both sides of brain), infundibulum, pituitary gland

Cerebrum

• Corpus callosum (communication btwn lateral hemispheres)

• Fornix (transmits signals from the hippocampus, assc. with memory, learning, emotion, to the mammillary bodies and thalamus

• Choroid plexus (network of capillaries in brain that produces CSF by filtering blood plasma)

Flow of CSF

heart → blood plasma → choroid plexus → ependymal cells → CSF → lateral ventricles → interventricular foramen → third ventricle (thalamus) → cerebral aqueduct → fourth ventricle (pons/cerebellum) → central canal OR median and lateral aperatures of fourth ventricle → subarachnoid space → arachnoid villi → superior sagittal sinus → heart

Cranial Nerve I

Olfactory I

• Sensory

• Responsible for carrying smell to the brain

Cranial Nerve II

Optic II

• Sensory

• Transmits visual info from retina to brain, allowing for sensation of visual stimuli

Cranial Nerve III

Oculomotor III

• Motor

• Movement of eyeball/eyelid

• Accommodation of lens

• Constriction of pupil

Cranial Nerve IV

Trochlear IV

• Motor

• Innervates the superior oblique muscle, moving the eye downward

Cranial Nerve V

Trigeminal V

• Both Sensory and Motor

• Sensory: provide touch, pain, and temp sensations from the ophthalmic, maxillary, and mandibular regions of the face

• Motor: controls muscles for chewing and innervates tensor tympani muscle in inner ear, damping chewing noises, shouting, thunder, etc

Cranial Nerve VI

Abducens VI

• Motor

• Controls the lateral rectus muscle, abducting the eye

Cranial Nerve VII

Facial VII

• Both Sensory and Motor

• Sensory: provides sensation from the anterior 2/3 of the tongue

  • Motor: controls facial expressions, controls production of tears and saliva

Cranial Nerve VIII

Vestibulocochlear VIII

• Sensory

• Cochlear branch: responsible for sensation of sound

• Vestibular branch: maintains balance and spatial orientation by sending info about head position

Cranial Nerve IX

Glossopharyngeal IX

• Both Sensory and Motor

• Sensory: provides taste sensation from posterior 1/3 of tongue and sensations from pharynx (throat)

• Motor: assists with swallowing, speech, and saliva production, monitors O₂, CO₂, and BP

Cranial X

Vagus X

• Both Sensory and Motor

• Sensory: taste and somatic sensation from pharynx and epiglottis

• Motor: swallowing, coughing, voice production, smooth muscle contraction, secretion of Gi tract, slows heart rate, constriction of respiratory pathways

Cranial Nerve XI

Accessory XI

• Motor

• Controls muscles in neck (sternocleidomastoid, superior trapezius)

• Head rotation and shoulder elevation

Cranial Nerve XII

Hypoglossal XII

• Motor

• Controls tongue movements required for speech, food manipulation, and swallowing

Spinal Nerve Anatomy

inside → outside

• axon → myelin sheath → endoneurium → bundles of axons (fascicle) → perineurium → bundles of fascicles → epineurium → spinal nerve

Phrenic nerve

• Cervical plexus

• Innervates diaphragm

Axillary nerve

• Brachial plexus

• Innervates deltoid and teres minor

• Abduction of arm

Musculotaneous nerve

• Brachial plexus

• Innervates anterior arm muscles (biceps brachii and brachialis)

• Flexion of arm and/or forearm

Radial nerve

• Brachial plexus

• Innervates posterior arm/forearm muscles

• Extension of forearm and wrist

Ulnar nerve

• Brachial plexus

• Innervates medial region of flexor digitorum profundus and all of flexor carpi ulnaris

• Sensory input from medial 1.5 fingers

Median nerve

• Brachial plexus

• Innervates most of the anterior forearm muscles

• Sensory input from lateral 3.5 fingers

Obturator nerve

• Lumbar plexus

• Innervates the medial thigh muscles

• Adduction of the thigh

Femoral nerve

• Lumbar plexus

• Innervates the anterior thigh muscles (quads, sartorius, psoas major, and illiacus)

• Extension of the leg

Sciatic nerve

• Sacral plexus

• Longest nerve in body

• Innervates posterior thigh muscles (hamstrings)

• Flexion of the leg, extension of the thigh

Tibial nerve

• Sacral plexus

• Innervates extensors of thigh/flexors of leg and posterior leg muscles

• Plantar flexion of foot and flexion of toes

Common fibular nerve

• Sacral plexus

• Innervates anterior leg muscles

• Extension of toes and dorsiflexion of foot

Cranial reflexes

Integrated at the level of brain via cranial nerves

Spinal reflexes

Integrated at the level of spinal cord via spinal nerves

Corneal Reflex

• Stimulation: stimulation of cornea

• Afferent nerve: trigeminal V

• Efferent nerve: facial VII

• Response: contraction of orbicularis oris muscles

• Cranial reflex

Salivary reflex

• Stimulation: smell, taste, sight, etc. of food

• Afferent nerves: facial VII and glossopharyngeal IX

• Efferent nerves: facial VII and glossopharyngeal IX

• Response: production of saliva by the salivary glands

• Cranial reflex

Pharyngeal reflex (gag reflex)

• Stimulation: stimulation of back of throat/soft palate

• Afferent nerve: glossopharyngeal IX

• Efferent nerve: vagus X

• Response: constriction of pharyngeal muscles and elevation of soft palate

• Cranial nerve

Meissner Corpuscles

• Encapsulated tactile receptors

• In dermal papillae (bumps), mostly in lips, palms, eyelids

• Light touch

• Low freq

• Textures → fine details and distinct shapes

Pacinian Corpuscles

• Encapsulated tactile receptors

• Deep in reticular layer of dermis/hypodermis, mostly in palms, soles, ext. genetalia

• Deep pressure

• High freq

• Strong tactile stimuli

Hair root plexus

• Unencapsulated tactile receptors

• In reticular layer of dermis

• Hair movement

Merkel discs

• Unencapsulated tactile receptors

• In s. basale of epidermis, mostly in ext. genitalia, lips

• ONLY detect light touch

Muscle spindles

• Proprioceptor

• In skeletal muscles

• Monitor change in muscle length

Golgi tendon organ

• Proprioceptor

• In junction where muscle and tendon meet

• Detects change in muscle tension

Krause end bulbs

• Thermoreceptors

• in dermis of skin and mucous membrane

• Detect cold temp

Ruffini corpuscles

• Thermoreceptors

  • in deeper layers of dermis

  • detect warm temps

• Proprioceptor

  • In deeper layers of the dermis, esp. around joints and fingers

  • Skin stretch and sustained pressure

Negative afterimage

When hands previously in cold and warm water are placed in room temperature water, the hand from cold water feels warm, while the hand from warm water feels cool due to the adaptation of skin's temperature receptors. The hand in hot water adapts quicker because its temperature is closer to body temperature.

Referred pain

ex: heart problems cause pain in chest and left arm (nerves nearby)

ex: brain freeze