Physiology 2

Humans are...

trichromats-three types of cones for blue, green, red corresponding to their frequency absorption maximum.

Structural organization for a muscle. Name the components and their relationships.

whole muscle-fasciculus-muscle fiber (myocyte)-myofibrils_myofilaments skeletal muscle->muscle fascicles>muscle fiber (myocyte)>Sarcoplasm>myofibrils>myocin>thick filaments actin-thin filaments. actin and myosin form a sarcomere

3 dimensions to any stimulus. Explain how stimulus intensity and duration are coded into sensory neuron action potentials

1) Intensity - coded by number of receptors activated and freq of action potentials 2) Duration-some receptors can adapt, or cease to respond 3) Location

Cerebellum location and primary function

"secretary" for all parts of the brain that participate in motor function, an integration and smoothing function. The cerebellum does NOT initiate motor function. receives and sends on the ipsilateral side.

Hypothalamus contains nuclei for...

(neural centers) for hunger, thirst (osmoreceptors), circadian rhythms, and ADH release. Hypothalamus is important in thermoregulation and "homeostatic" control mechanisms in general. Identify key hypothalamic functions

components of the vestibular apparatus

Utricle - linear accelerations horizontally Saccule- vertical linear accelerations semicircular canals-rotational accelerations.

explain how the same neurotransmitter (norepi) can have both excitatory and inhibitory effects on different tissues - specificity of the receptor determines the nature of the response...not the response

...

Vagus nerve is...

10th nerve that is key to many internal organs (parasympathetic nervous system)

Somatosensory input from skin and proprioceptors in joints:

3 orders of nerves conduct signals thru the thalamus to the parietal sensory cortex. Disproportionate representation of the body on the post-central gyrus of the parietal lobe. "homunculus" provides a map for locating the stimulus site.

Identify key components of spinal reflex

A spinal reflex initiates a response without input from the brain.

Alpha1, Beta2, Beta1

Alpha 1 stimulation from sympathetic - skeletal muscle arterioles constrict. Beta 2 effects-dilate arterioles from hormonal epinephrine Bronchiole dilation is a beta 2 effect (albuterol). Heart rate increase is a beta 1 effect.

Sound transmission

Bones of middle ear: Malleus, Incus, Stapes sound waves strike tympanic membrane, transferred into bones, goes through oval window, vibrates fluid in cochlea, hair cells bend, NT release and action potentials through cochlear nerve to brain sound waves can be increased in freq (hertz) intensity/amplitude (decibels-DB) power of 10 increase for every 10 decibel increase

What are the roles of CSF in the CNS? Where is cerebrospinal fluid generated in the CNS and where is it reabsorbed? **Associate the ependymal glial cell with the choroid plexus. ** Know the ventricles of the brain: lateral, third and fourth. CSF cirulates through them and around the CNS in the space between the PIA matter and ARACHNOID MEMBRANE.

Brain floats in CSF. Exchange of materials b/t neural cells and interstitial surrounding brain. **FORMED BY CHOROID PLEXUSES. **reabsorbed in arachnoid villi - sagital sinus and by lymphatics

Functional organizations of the brain

Brain plasticity is the capacity to transfer a function to another brain region. 95% RT handed, 70% LFT <<speech localization into left hemisphere. Broca-speech production wernicke's area-comprehension

potential sources of muscle fatigue

Ca leaks cause fatigue? Lactate no longer a likely cause. depletion of glycogen stores due to oxygen. decrease calcium release from slowed p release from myosin. changes in na-k-atpase activity, accumulating lactate levels. CNS-psychological effects, protective reflexes...no decrease in ATP noted.

derivatives of the amino acid tyrosine

Dopamine, norepinephrine (postganglionic sympathetic, neuron NT and hormone) epinephrine (hormone of adrenal medulla) are all derivative.

Most visceral organs demonstrate this.

Dual intervation from both sympathetic and parasympathetic neuron whose actions are opposite. Antagonistic (complementary) control demonstrated by ANS. exceptions are: 1. innervated blood vessels are sympathetic only: alpha1 receptors mediate vasoconstriction, beta-2 are inhibitory and mediate vasoldilation and bronchiole dilation. 2. sweat glands are sympathetic only 3. salivary glands both. similar increase in saliva but differences in composition

What are nuclei and ganglions and where do they occur in the CNS?

Gray matter consists of sensory and motor nuclei. The Cerebrum consists of basal nuclei. Many nuclei are associated with the reticular formation. Neurons are about 10% of total number of brain cells - glial cells.

Diencephalon functions

Includes thalamus and hypothalamus. Thalamus forms walls of third ventricle on brain. thalamus a sensory and motor relay center with connections to: cerebral cortex, basal ganglia, hypothalamus, and brainstem. Thalamus also functions as a filter for what goes to the cortex.

Hypothalamus does what?

Interconnects the brainstem and the endocrine system. Recall hypothalamus as source of hormonal releasing factors that signal the anterior pit gland. Also, the posterior pit secretions, ADH and oxytocin, come from the hypothalamus.

Summary map of muscle contraction. sequence of events for depolarization of the NMJ?

Lower motor neuron from spinal cord triggers calcium flux to release acetylcholine neurotransmitter at the myoneural junction. ACh from the axon binds to nicotinic receptors on motor endplate causing Na+ influx and change in EPP. Sufficient EPP triggers an action potential across the muscle sarcolemma. Analogous to depolarization of neuron.

How does the muscle action potential move along the sarcolemma? What events turn off Ca flow, reduce Ca levels, and result in relaxation of muscle fiber.

Muscle action potential travels along the sarcolemma and into the muscle fiber along T tubles and results in the release of Ca++ from the sarcoplasmic reticulum. Recognize dihydropyridine and ryanodine as receptors linking action potential to Ca++ release. This calcium flow is the coupling event bt neurologic excitation of the muscle fiber and mechanical contraction of the muscle sarcomeres. **Sarcoplasmic Ca++ ATPase pumps Ca back into SR. **Decrease in cytosolic Ca causes Ca to unbind from troponin **Tropomyosin recovers binding site. myosin filaments release and go back to relaxed position.

3 phases of voluntary movement. Sketch relationships of their key components.

Planning movement: idea>cortical association areas> , initiating, executing. will need to write this down.

explain max oxygen consumption, lactate threshold, and oxygen debt.

Recall phosphocreatine (Pcr) as a quick way to generate ATP for 5-10 sec burst. PCr not used directly by muscle. Phosphocreatine, glycolysis, and glycogenolysis do not require oxygen for ATP generation "anaerobic" glycolysis alone can supply maximal energy expenditure for only 1-2 min before lactate turnover is overwhelmed. Accumulation of lactate, H+ and K+ impair metabolic processes.

adrenal medulla. which NS?

Sympathetic POSTGANGLIONIC cell. SYMPATHOADRENAL response releases the hormone epinephrine that also elevates heart rate, increases blood glucose levels and production.

ANS divisions and classifications

Sympathetic-preganglionic fibers short. Thoracic parasympathetic-fibers originate from cranial sacral, preganglinoic fibers longer

Significance of length-tension relationship for generating force of contraction. Explain how force of contraction can be voluntarily adjusted.

Too much or too little overlap of thick and thin filaments in resting muscle results in decreased tension.

ANS NT

acetylcholine for preganglionic, parasympathetic postglanglionic fibers release acetylcholine as well. sympathetic release norepinephrine/noradrenaline

Recognize 4 key lobes of cerebrum and their basic functions. Be able to associate basic components of brain: brain stem, diencephalon, cerebellum and limbic system with basic functions

brain stem - regulate involutnary functions, reticular formation: arousal, sleep, tone, pain. eye movement diencephalon thalamus-integrating center. relay station for sensory and motor info. pineal gland-melatonin secretion. hypothalamus. pituitary cerebellum movement coordination limbic system -amygdala and hippocampus

Area of a sensory fibers receptive field is ___ related to the density of receptors found here. An example of this.

inversely. Demonstrated by the two-point touch threshold where fingertips are most sensitive while back and leg skin are least discriminating for tactile acuity.

parts and key associated functions of limbic system

cingulated gyrus (part of cortex), septal nuclei, amygdala (fear and aggression), hippocampus. Associate limbic system and hypothalamic connections w/ general coordination of fear, feeding and ex behaviors, and goal directed behavior (reward/punishment). Associate memory with temporal lobe and hippocampus. associate amygdala with memory of fear responses.

alpha and gamma motor neurons are ____ by upper motor neurons.

co-activated

Law of specific nerve energies

each sensory nerve has a characteristic sensaiton produced by an above threshhold stimulus. In a graded potential, a stronger stimulus results in greater Na+ influx, and there is no refractory period.

Ataxia

inability to coordinate movements, associated with cerebellar dysfunction

Define isotonic, isometric, and eccentric contractions. **Recognize most muscle work as third class lever systems and at a mechanical disadvantage for torque. What is the advantage of this arrangement for movement of the hand or foot?

isotonic- muscle contracts, shorten, creates enough force to move the load. isometric-muscle contracts, but does not shorten. force created cannot move load. eccentric-the muscle elongates while under tension due to an opposing force greater than the muscle generates Because insertion of biceps is close to fulcrum, a small movement of the biceps becomes a much larger movement of the hand.

Why is cocaine considered to be sympathomimetic?

it blocks reuptake of dopamine and norepi. and promotes sympathetic nerve effects.

injury to LMN vs UMN

lower motor neuron - flaccid paralysis upper motor neuron - spastic paralysis due to loss of inhibitory effect on LMN

Important in the regulation of respiration and heart rate in cardiorespiratory system.

medulla oblongata - receiving center for afferent signals from heart and lungs (via Vagus) and connects these signals to autonomic nervous system.

Brainstem parts and functions

midbrain-relay center for both sensory and motor pathways. substantia nigra connects to basal ganglia and limbic system and is involved in motor coordination. **Dopamine is the NT and Parkinson's is associated with problems here. Pons is a relay station and integrates input from the cerebellum and contains cranial nerve nuclei. Two autonomic centers are here. Medulla contains all ascending (sensory) and descending (motor) tracts bt the brain and spinal cord. Location of the DECUSSATION - CROSS OVER - of nerve tracts results in contralateral representation of the brain.

muscle spindle vs golgi tendon organ: location, length of muscle vs tension on tendon, monosynaptic reflexive muscle reset vs disnaptic inhibition of alpha motoneuron.

muscle spindle - sends info about muscle stretch. gamma motor neuron-intrafusal. alpha-from spinal cord. Tonically active and firing even when the muscle is relaxed. (restores arm position after extension) Golgi-tendon potects the muscle from excessively heavy loads by causing the muscle to relax and drop the load. polysnaptic with interneuron.

Mechanism for oxidative capacity depends on... Oxidative capacity requires oxygen ___ to maintain ATP ___

myocyte myoglobin content (oxygen supply), capillary density (blood flow), myocyte mitochondrial density (oxidative phophorylation ATP production), and myosin ATP-ase activity (slow isozyme) flow

opposites

nicotinic vs muscarinic ACh receptors, alpha vs. beta adrenergic receptors

visual fields project to...

opposite half of retina and contralateral occipital cortex

Trace signal from uppter motor neuron down the pyramidal tract of spinal cord to anterior horn cell of lower motor neuron...out to target muscle. 2 tracts

pyramidal and extrapyramidal

rods v cones

rods-low light black and white vision cones- sharp color vision in bright light

microanatomy of myofibril and myofilaments. What is the fundamental unit of contraction? Know its components and action. Striations are... How do actin and myosin filaments interact with each other?

sarcomere is the fundamental unit of contraction. Striations are light microscopic appearance of alternating dark A bands and alternating light I bands. Thin actin and thick myosin filaments do not shorten during contraction. Actin slides over myosin.

define motor unit

somatic motor neuron with its cell body in the anterior horn of the spinal cord and all the muscle fibers it innervates - understand implications of innervation ratio - number of muscle fibers per single neuron. lower ratio enables finer control (RULE) Recall motor recruitment as the process for getting a larger number of motor units involved for improving strength by motor learning without hypertrophy.

pain neurotransmitters. Explain built in analgesic system in the brain.

substance p and glutamate. Brain has a built in analgesic system based on opiate receptors that can bind endogenous endorphins and enkephalins. Exogenous opiods like morphine bind to these receptors. Example of presynaptic inhibition on the pain fiber terminus.

sympathetic vs parasympathetic signals

sympathetic NS sends signals to skin effectors: red in the face with anger, hair stands up with fear. Parasympathetic NS is craniosaccral distribution and not "wired" to skin response. "Rest and digest"

fight or flight "mass activation"

sympathetic chain of ganglia allows a single preganglionic neuron to synapse at mulitple levels with postganglionic neurons. A single postganglionic neuron receives input from mulitple levels of preganglionic nerves. MASS ACTIVATION is the net effect and the coordinated sympathetic stress response of "flight or fight"

sympathetic vs parasympathetic NT receptors

target cells: sympathetic is adrenergic. parasympathetic is muscarinic. both ganglionic synapses are ach on on nicotinic receptor.