Monday, December 13, 2010

Endocrine system

Endocrine system
                Continues to grow the more we understand it
                Maintains homeostasis
                                Communication
                                Integration
                                Control
                Detects imbalances
                                Hormones act as messengers
                                Hormones regulate a wide variety of bodily functions
                                Small amounts of hormones in the body
                                                Hormones get moved around by the blood
                Slow response, yet is long lasting
                No ducts
Common endocrine organs
                Hypophysis cerebris (pituitary gland)
                Thyroid
                Parathyroid
                Pineal
                Adrenal
                Pancreas
                Ovary
                Testes
                Kidney
                Thymus
Pituitary gland
                Small .5g
                Below brain in sella turcica of sphenoid bone
                8 different hormones
                                Cause wide range of activities
                2 lobes
                                Arising from different tissues
                                Act as different glands
                Adenohypophysis
                                Anterior side
                                Typical gland
                                6 hormones
                                                1 prolactin (lactogenic)
                                                                Stimulates production of milk
                                                2 Growth hormone (somatotropin)
                                                                Promotes protein synthesis
                                                                More cell divisions + bigger cells
                                                                Dominate in skeletal and fat cells
                                                Tropic hormones (cause other glands to produce its hormones)
                                                3 Thyroid stimulating (TSH)
                                                4 adrenocorticotropic (ACTH) adrenal cortex – Glucocorticoid
                                                Gonadotropic
                                                5 follicle stimulating (FSH)
                                                6 luetinizing hormone (LH)
                                Hypothalamus regulates
                Nuerohypophysis
                                Holds ADH & oxytocin
                                                Both produced by nuclei in hypothalamus
                                ADH & oxytocin are just released from here
Thyroid
                Below larynx
                In front of trachea
                Bi-lobbed gland
                Rich blood supply
                Follicular cells
                                Produces thyroid hormones
                                Increases Ca in blood
                                                By removing Ca from bone
                Parafollicular cells
                                Produce thyrocalcitonin
                                Decreases Ca in blood
                                                Deposits on bone
                Triiodothryronine
                Tetraiodothyronine
                Colloid storage
                Regulates metabolism
                Essential for proper growth & development
                Traps iodine
Parathyroid
                Produces parathyroid hormone
                Increases blood Ca
Adrenal/Suprarenal gland
                2 parts
                                Each part functions as its own gland
                Outer cortex (life essential)
                                Gland tissue
                                Produces steroids
                                Starts with cholesterol
                                Mineralcorticoid
                                                Aldosterone
                                                Tells kidneys to re-absorb Na
                                                Increases BP
                                Glucocorticoids
                                                Cortisol (hydrocortisone)
                                                Normal glucose metabolism
                                                BACKUP for adrenal medulla
                Inner medulla
                                Nervous tissue
                                Epinephrine
                                Norepinephrine
                                                Both prepare body for stress
                                                Fight or flight response
                Regulates metabolism
                Handles stress
Pancreas
                Islands of endocrine cells
                β cells produce Insulin
                                Decreases blood sugar
                α cells produces Glucogon
                                increases blood sugar
Pineal gland
                Part of diencephalon
                Secretes melatonin
                Body clock
                Circadian rythym
                Possible plays a role in the female reproductive system
                Season affective disorder (SAD)
                                Mild depression in winter
Thymus
                2 hormones
                Thymosin
                Thymopoesin
                                Involved in production of T-Cells
Reproductive hormone
                Male
                FSH
                                Stimulates seminiferous tubules
                LH
                                Stimulates Interstitial cells to produce androgen
                Female
                FSH
                                Stimulate growth of follicle
                                Follicle then produces estrogen
                LH
                                Causes release of 2nd oocyte
                                Estrogen levels decrease for a short time

Saturday, December 4, 2010

Cranial Nerves Need to Know

List of cranial nerves
#NameSensory,Function
  Motor 
  or Both 
IOlfactory nervePurely SensoryTransmits the sense of smell; Located in olfactory foramina in the Cribriform plate of ethmoid
IIOptic NervePurely SensoryTransmits visual information to the brain; Located in optic canal
IIIOculomotor nerveMainly MotorInnervates levator palpebrae superioris, superior rectus, medial rectus, inferior rectus, and inferior oblique, which collectively perform most eye movements; Also innervates m. sphincter pupillae. Located in superior orbital fissure
IVTrochlear nerveMainly MotorInnervates the superior oblique muscle, which depresses, rotates laterally (around the optic axis), and intorts the eyeball; Located in superior orbital fissure
VTrigeminal nerveBoth Sensory and MotorReceives sensation from the face and innervates the muscles of mastication; Located in superior orbital fissure (ophthalmic nerve - V1), foramen rotundum (maxillary nerve - V2), and foramen ovale (mandibular nerve - V3)
VIAbducens nerveMainly MotorInnervates the lateral rectus, which abducts the eye; Located in superior orbital fissure
VIIFacial nerveBoth Sensory and MotorProvides motor innervation to the muscles of facial expression, posterior belly of the digastric muscle, and stapedius muscle, receives the special sense of taste from the anterior 2/3 of the tongue, and provides secretomotor innervation to the salivary glands (except parotid) and the lacrimal gland; Located and runs through internal acoustic canal to facial canal and exits at stylomastoid foramen
VIIIVestibulocochlear nerve Mostly sensorySenses sound, rotation and gravity (essential for balance & movement). More specifically. the vestibular branch carries impulses for equilibrium and the cochlear branch carries impulses for hearing.; Located in internal acoustic canal
IXGlossopharyngeal nerveBoth Sensory and MotorReceives taste from the posterior 1/3 of the tongue, provides secretomotor innervation to the parotid gland, and provides motor innervation to the stylopharyngeus. Some sensation is also relayed to the brain from the palatine tonsils. Sensation is relayed to opposite thalamus and some hypothalamic nuclei. Located in jugular foramen
XVagus nerveBoth Sensory and MotorSupplies branchiomotor innervation to most laryngeal and all pharyngeal muscles (except the stylopharyngeus, which is innervated by the glossopharyngeal); provides parasympathetic fibers to nearly all thoracic and abdominal viscera down to the splenic flexure; and receives the special sense of taste from the epiglottis. A major function: controls muscles for voice and resonance and the soft palate. Symptoms of damage: dysphagia (swallowing problems), velopharyngeal insufficiency. Located in jugular foramen
XIAccessory nerveMainly MotorControls sternocleidomastoid and trapezius muscles, overlaps with functions of the vagus. Examples of symptoms of damage: inability to shrug, weak head movement; Located in jugular foramen
XIIHypoglossal nerveMainly MotorProvides motor innervation to the muscles of the tongue (except for the palatoglossus, which is innervated by the vagus) and other glossal muscles. Important for swallowing (bolus formation) and speech articulation. Located in hypoglossal canal

Nervous System

Nervous System
                Respond & act to environment
                Memory, thinking, feeling, reasoning
                Biochemical

                Network of nerve cells
                                Function to receive assimilate & transport information
                Sensory neurons
                                Come from sense organs
                                Go to the central nervous system (CNS)
                                Afferent
                Internuerons
                                Evaluate signal from sensory
                Motornuerons
                                Carry instructions back to effector organ for action
                                Efferent

CNS = Brain & spinal cord
PNS = 31 paired spinal nerves & 12 paired cranial nerves

                Afferent = sensory
                Efferent = motor
                                Somatic NS = skeletal muscle
                                Autonomic = glands & smooth muscles
                                                Sympathetic = response to stress (fight or flight reaction)
                                                Parasympathetic = Normal functions

Neuron
                transport information
                excitable
                conductive         
Neuroglia
                support & nourish neurons

dendrites
                carry info to the neuron
axons
                carry info away from neuron

nerve fiber
                axon unless otherwise specified

mylinated axons
                have schwan cells wrapping the axon
                much faster data transport
                white matter
                has nodes of Ranvier
                                small gap between each schwan cell
unmylinated
                slower
                grey matter

synapse
                a region between nerves
synaptic end bulb
                small encapsulated bodies at the end of a nerve
synaptic vesicle
            release ACh (begins synaptic transmission)
            or AChE (ends synaptic transmission)

axons running same direction are bundled
white matter = mylinated axons
grey matter = unmylinated axons & cell bodies

Nerves
            Bundle of axons outside of CNS
            Mylinated or unmylinated

Tract
            Bundle of axons inside the CNS

Ganglion (grey)
             Collection of cell bodies outside the CNS

Nucleus
            Collection of cell bodies inside the CNS

Spinal Cord
                Starts just as brain stem leaves foramen magnum
                End at L1~L2
                Lower it degrades as Conus medularis
                                Non nervous tissue from conus to coccyx
                                Filum terminale
                                                delicate strand of fibrous tissue
                                                gives longitudinal support to the spinal cord
                                Cauda equinae
                                                within the lower end of the spinal column
                                                consists of nerve roots and rootlets from above
                                                The space in which the cerebrospinal fluid is present is actually an extension of                                                                                 the subarachnoid space
Cross section of the cord
                Anterior median fissure
                Posterior median fissure

                Grey matter appears “H” shapped
                Opening on the crossbar of the H is for the canal
                                Divides posterior/anterior commissure
                                Canal is cerebrospinalfluid (CSF)
                White matter fills in spaces around the grey matter
                                White matter tracts
                                                Too brain
                                                                Afferent/sensory
                                                Away from brain
                                                                Efferent/motor

Spinal nerves
Common nerve
                Anterior root = motor
                posterior root = sensory
               
The meninges
                the system of membranes which envelopes the central nervous system
                Dura mater
                                Tough outer membrane covers roots and extends the length of the cord
                Sub Dural Space
                                Between dura mater and arachnoid
                                For serous fluid to lubricate
                Arachnoid
                                Spider like webbing covers roots and extends the length of the cord
                Sub arachnoid space
                                Contains CSF
                Pia mater
                                Outer layer of the brain, delicate, attaches by roots of nerves
                                Attaches with denticulate ligaments
                Bone lined with epidural fat

Spinal Nerves
                31 pairs
                8 cervical
                                1st nerve comes off before 1st CSpine
                12 thoracic
                5 lumbar
                5 sacral
                1 coccyx

                Nerves leave between the vertebrae
                plexus  
                                Regrouping of the nerves
                                Cervical plexus
                                                For shoulders and neck
                                Brachial plexus
                                                Arm
                                Lumbar plexus
                                                Down to lower extremities
                                Sacral
                                                1st 3 join to form sciatic nerve (the largest nerve)
                                                Skin & posterior thigh
Seat of reflex actions
                Automatic & involuntary
                Simple reflex arc
                                Sensory receptor
                                Dorsal root
                                Association neuron
                                Ventral root
                                Effector
                Not all stimuli cause a response
                                Ex. Inhibition response

Brain
                In the cranial cavity
                Ends at foramen magnum
                Dominates rest of NS
                Billions of neurons
                More neurological
                1300grams 3pounds
                Females smaller
                Smaller with age
                Neurons only undergo mitosis in prenatal & slightly postnatal
                Roughly full size at age 18
                                Rapid growth during that first half
                4 principal regions
                                Cerebrum
                                Cerebellum
                                Diacephalon
                                                Thalymus + hypothalymus
                                Brain stem
                                                Medulla oblongata + pons + mesencephalon (midbrain)

                Dura mater
                                Periosteal layer
                                Meningeal layer
               
                CSF
                                140ml total
                                Mostly water
                                Protein, glucose, salts, urea
                                Produced in choroid plexuses
                                Which then goes to
                                4 ventricles
                                Spaces within the brain
                                1 & 2 are lateral
                                3 slit
                                4 diamond shaped
                                CSF then goes to central canal & subarachnoid space
                                Circulates

Brain Stem
                Continuous with the spinal cord                               
                Structurally the same
                                Just a slightly different location
Medulla oblongata
                                White matter traces
                Reticular formation
                                Interlacement of white and grey mater
                Pyramids
                                Moving laterally on each side of the medulla oblongata
                Decussion of the pyramids
                                Crossing of fibers
                                Why left brain controls right side of body & vice versa

                VITAL control center
                Respiratory
                                Medullary rhythmicity
                                Keeps breathing in rhythm
                Vasomotor
                                Vasoconstriction & dilation
                                Controls blood pressure
                Cardiac center
                                Controls rate and strength of contractions

                NONvital controls
                                Coughing
                                Sneezing
                                Vomiting
                                Swallowing
                                Hiccups
               
                has 9th 10th 11th & 12th cranial nerves

Pons
                Horizontal groove separates from medulla oblongata
                Bridge in structure & function
                Connects forebrain to spinal cord & midbrain
                Pnuemotaxic
                Apnuetaxic

                Has 5th 6th 7th & 8th cranial nerves

Midbrain
                Below cerebrum
                Above pons
                Mostly white matter
                Ventral surface
                                Cerebral peduncle
                                                Rope like structures
                Has 3rd 4th and part of 5th cranial nerves

Cranial nerves
                Named by distribution or function
                Can be motor sensory or mixed
                                Most are mixed

Cerebellum
                2nd largest
                Posterior & inferior
                Deep fissures separate into lobes
                Vermis hold the 2 hemispheres together
                Grey outside
                White inside (arbor vitae
                3 functions related to skeletal muscle
                                Skilled movements
                                Posture
                                Coordination/equilibrium/balance

Diencephalon
                Deep within cerebrum
                Midbrain
                Thalamus & hypothalamus
                Thalamus
                                                Circular
                                                Major relay for sensory input
                                Grey Mater
                                Lateral walls of 3rd ventricle
                                Large axons enter
                                                Sensory input
                                Large axons leave
                                                Leave to cerebral cortex
                                                1 exception is olfactory nerve
                                Pain temperature & touch (sensory inputs)
                Hypothalamus
                                Below thalamus
                                Link between mind and body
                                Links nervous & endocrine systems
                                                via the pituitary gland
                                Pleasure & reward center
                                Maintains homeostasis
                                Coordinator of autonomic (involuntary) activities
                                Causes bodily functions to shown as expressions
                                Produces ADH (antidiuretic hormone) or vasopressin
                                Produces oxytocin
                                Plays a central role in the waking state
                                controls body temperature, hunger, thirst, fatigue, sleep, rage, aggression
                                also controls circadian cycles
                                                A circadian rhythm is a roughly 24-hour cycle in the biochemical, physiological,                                                    or behavioural processes of living entities
Cerebrum
                Surface is convoluted
                Gyris
                                Raised area
                Sulci
                Fissures
                                Divides right and left hemispheres
                                Corpus callosum connects
                External grey mater
                Internal white mater
                                Deeper has grey islands
                Cortex is thin
                                Yet has 6 layers
                                Made of billions of axons and cell bodies
                4 lobes
                Parietal, temporal, frontal, and occipital
                Tracts of white mater
                                Association tracts
                                                Connect 1 gyrus to another gyrus in the same hemisphere
                                Commissure tract
                                                Connect 1 gyrus of the right hemisphere to the homologous gyrus on the left                                                    hemisphere
                                                Found in the corpus callosum
                3 functions
                                Sensory, motor, integrated
                Displays lateralization
                                Example is that speech center of the brain is found is the left hemisphere
Cortex
                Responsible for awareness of self, environment, feelings, and other beings
                Conscious
                Higher mental processes
                                Memory
                                Logic
                Limbic system
                                Wishbone shaped
                                Surrounds upper end of brain stem
                                Emotional aspects
                                                Behavior of survival
Autonomic nervous system (ANS)
                Subconscious
                Part of peripheral nervous system (PNS)
                Efferent
                Regulates smooth muscle, cardiac muscle & glands
                                Examples
                                Dilation of pupil
                                Vasoconstriction
                                Vasodilation
                                Heart rate
                2 axons involved
                                1st preganglionic
                                2nd postganglionic
                Can be ACh or NE (norepinephrine)
                Dual innervation
                                Sympathetic & parasympathetic
                                Sympathetic
                                                Near spinal cord
                                                So 1st axon is short
                                                2nd axon is long
                                Parasympathetic
                                                Near organ
                                                1st axon is long
                                                2nd axon is short