Physiology EXAM 1

define homeostasis

"standing still" maintaining relatively stable state of conditions in the body

spinal cord organization

- extend from base of brain stem to base of spine - regions along trunk attach to PNS spinal nerves: cervical, thoracic, lumbar, sacral, coccygeal - forked structure of spinal nerves ➣ they are mixed nerves: sensory AND motor ➣ dorsal (back) carries sensory (afferent) info to CNS ➣ ventral (belly side) carries motor (efferent) info to muscles & glands

electrical synapse

- gap junctions: tunnels called connexons - bidirectional or one-way flow - speed and synchronization effect

what does the CSF provide?

- mechanical protection: CNS is buoyant, floats in CSF; this provides padding, protection from bruising, also reduces weight and pressures on brain (blood pressure, local pressure on neurons, nerves) - chemical protection: environment for chemical signaling - nutrient delivery, waste exchange: CSF is dynamic: made constantly and flushed out to the circulatory and/or lymph systems

brain

- simple multicellular organisms have nerve nets; increasingly complex brains cluster neurons - evolution of clusters led to forebrain, which in humans dominates the brain; brain is precious and must be sheltered/protected

protection of the brain

- strategy of many layers with different physical and chemical properties - skin (epidermis, dermis) - cranium - meninges (aka membranes) ➣ dura mater: dense connective tissue ➣ arachnoid mater: loose connective tissue ▶ subarachnoid space ▶ cobweb-like spaces hold the cerebrospinal fluid (CSF) ▶ brain also contains caverns that contain CSF: lateral ventricles (left, right), third ventricle, fourth ventricle (which is continuous with the central canal of the spinal cord) ➣ pia mater: thin membrane directly adherent to brain, spinal cord - neurons of brain ➣ blood-brain barrier (BBB) ➣ glia

chemical synapse

- uses neurotransmitters - know the 7 types of neurotransmitters ⇨ 6 are small molecules: acetylcholine, amino acids, amines, purines, gases, lipids ⇨ 1 is larger, the neuropeptides ⇨ CNS uses many neurotransmitters ⇨ PNS: mainly acetylcholine, norepinephrine, epinephrine

know the composition and characteristics of ECF and ICF

- what ions they contain - how changes in these ions or in charge will affect the polarization state of the cell ECF: ✰ Na+: high ✰ K+: low ✰ Cl-: high ✰ anionic proteins & phosphates: low ✰ Ca++: high ICF: ✰ Na+: low ✰ K+: high ✰ Cl-: low ✰ anionic proteins & phosphates: high ✰ Ca++ low

afferent sensory systems

-sensory pathways detect -neural pathways conduct to CNS

2 somatic sensory pathways

1) crossover in spinal cord (synapse in dorsal horn): coarse touch, temperature, nociception (*some nociception are reflexes that do not involve brain) 2) ascend to medulla and cross over: fine touch, proprioception, vibration sensory pathways synapse in thalamus, sensations are perceived in the primary somatic sensory cortex

neuron function relies on 4 types of integral membrane proteins, which are membrane channels

1. leak 2. ligand gated 3. mechanically gated 4. voltage gated

what are the PNS glia cell types?

Schwann

astrocyte

a star-shaped glial cell with numerous processes (extensions) that run in all directions -most numerous -maintain BBB -maintain chemical environment

oligodendrocyte

a type of glial cell that forms myelin in the central nervous system

process of synaptic signaling

action potential ➝ depolarization opens Ca++ voltage-gated channels ➝ Ca++ triggers vesicle/membrane fusion ➝ neurotransmitter release

define action potential

arise at a trigger zone, typically axonal hillock ✺ ultimately propagate along the axon; regenerated away from axon ✺ when Na+ flows in, local current flow triggers voltage-gated Na+ channels in adjacent membrane to open ✺ involve voltage-gated channels - voltage-gated channels: Na+ and K+ - location, amplitude, all-or-nothing, distance traveled - know sequence of ion flow, ion permeability, and cycle of each gate opening/closure - define the refractory period (incapable of responding) ➣ absolute: Na+ open and then close ➣ relative: Na+ are resting; stronger stimulus than normal needed to trigger action potential because not all the gates are reset and K+ gates are open (losing + charge) - propagation: regenerative nature - conduction: continuous, saltatory - stimuli can be subthreshold, threshold, suprathreshold - effect of chemical factors on electrical activity: K+, Na+, Ca++ - clinical application: how conduction is altered in demyelinating diseases

law of mass balance

balance of input and metabolic production with output via excretion or metabolic removal

diencephalon

between brain - thalamus, pineal gland, hypothalamus, pituitary gland

lipid component of cell membrane

bilayer = fluid mosaic model: sea of lipids with protein rafts (75% phospholipids, 20% glycolipid, 5% cholesterol- percentage impacts water permeability)

define central nervous system (CNS)

brain and spinal cord

dendrites

branchlike parts of a neuron that are specialized to receive information

define AFFERENT division

brings information from the body (peripheral organs) TO the central nervous system ✷ somatic senses: tactile, thermal, pain, proprioceptive ✷ special senses: smell, taste, vision, hearing, equilibrium

ligand gated channels

channel that opens when a neurotransmitter attaches ➣ particular molecule must be there as a key

leak channels

channels that are always open and allow ions to move along their gradient ➣ random, leak across just based on opening and closing; molecules move with respect to electrochemical gradients

limbic system

cingulate gyrus, hippocampus, amygdala; the emotional brain

capillary in BBB

composed of epithelial cells with many tight junctions TIGHT JUNCTION: interlocking protein complexes; seals adjacent cells to solute flow

define feedback system

controlled variable ➞ monitored by receptors ➞ control center ➞ effectors ➞ response

what allows the 2 hemispheres of the brain to communicate?

corpus callosum; band of white matter that connects the hemispheres (axons)

stimulus modality

encoded by sensory receptor and neural pathway = "labeled lines" ❊ thalamus = relay station example: taste is perceived when a stimulus activates a gustatory receptor and its path to the gustatory cortex in the insula region of the brain example: smell is perceived when a stimulus activates an olfactory cortex in the temporal lobe of the brain

define lateral inhibition

enhances contrast and makes a stimulus easier to perceive

midbrain

eye movement

define cerebral lateralization, give examples

functional areas in the cerebral hemispheres that are NOT symmetrical concentrated on LEFT: ✪ language, verbal, mathematic skills; "analysis" ✪ examples: reasoning, numerical/scientific skills, spoken & written language, use and understanding sign language concentrated on RIGHT: ✪ spatial skills, "creative" ✪ examples: music and artistic awareness, space and pattern perception, recognizing faces, patterns, emotional content of language, odor discrimination

ependymal cell

glial cell that lines membranes within the brain and spinal cord and helps form cerebrospinal fluid

what can pass with regulated passage through blood-brain barrier?

glucose and other water-soluble substances example: glucose transporter proteins in the membrane quickly move glucose to the brain; brain needs a lionshare of glucose in our bodies for its anaerobic metabolism

regions of gray and white matter

gray matter: cortex, basal ganglia, limbic system white matter: corpus callosum

basal ganglia

help control movement and muscle tone

stimulus location

how sensitive various areas of the body are; how innervated, how big the receptor fields are, if there is any overlap ❊ 2 point discrimination ❊ acuity: sharpness of perception example: back has big receptor fields that do not overlap; body does not know the exact place; lack acuity with big sensory receptors example: hand has very small sensory fields, lots of overlap, body can discriminate and tell where stimulus is example: auditory uses timing! -uses timing differences to localize sound

thalamus

integrating center and relay station for sensory and motor information

medulla oblongata (medulla)

involuntary functions, control heart rate, breathing, sense blood pressure, sense toxins in blood and will stimulate vomit reflex

what molecules are impermeable to cell membrane?

ions, large uncharged polar molecules

define selective permeability

know what can pass the cell membrane and what cannot

cell body

largest part of a typical neuron; contains the nucleus and much of the cytoplasm

cerebrum

largest part of the brain, the "seat of intelligence", walnut appearance with gyri and sulci - 2 hemispheres - frontal lobe, parietal lobe, temporal lobe, occipital lobe, insula

hypothalamus

links nervous and endocrine systems, secretes hormones

stimulus intensity and duration

longer or stronger stimuli release more neurotransmitter -intensity encoded by frequency of action potentials

define graded potential

membrane potential changes that vary in amplitude depending on the stimulus ✺ typically occur on dendrites or the cell body ✺ stronger stimuli affect more membrane proteins and cause graded potentials of higher amplitude ✺ summation: graded potentials can add up when stimuli happen close together - mechanical and ligand-gated channels - location, amplitude, distance traveled, depolarize, hyperpolarize - summation, no refractory period - local current flow, decremental nature

brain stem

most ancestral, primitive part of brain - midbrain, pons, medulla, reticular formation

white matter

myelinated axons

what molecules are highly permeable to cell membrane?

nonpolar molecules

temporal lobe

olfactory cortex, auditory cortex, auditory association area

what are the CNS glia cell types?

oligodendrocyte, microglial cell, astrocyte, ependymal cell

voltage gated channels

open and close in response to changes in membrane potential

mechanically gated channels

open and close in response to physical deformation of receptors ➣ particular pressures applied

microglial cell

phagocytic glial cell that removes waste products from the central nervous system

pons

relay station between cerebrum and cerebellum; coordinate breathing with medulla

cerebellum

second largest part of brain; coordinates movement

pituitary gland

secretes hormones that affect other glands and organs

pineal gland

secretes melatonin to regulate circadian rhythm

4 attributes of sensory coding

sensory coding: how the CNS tells the difference among all the input stimuli - modality, definition of labeled line - location, definition of acuity ➣ 2-point discrimination ➣ timing ➣ lateral inhibition - intensity - duration

parietal lobe

sensory cortex, sensory association area

3 types of neurons

sensory neuron, interneuron, motor neuron

frontal lobe

skeletal muscle movement, motor cortex

what molecules are moderately permeable to cell membrane?

small uncharged polar molecules; cross via gaps as lipids move, # of gaps depends on the amount of cholesterol

what dictates function and behaviors of cells?

structure and composition (features) - size, shape, organelles, gene expression

Schwann cell

supporting cells of the peripheral nervous system responsible for the formation of myelin

synaptic end bulb

swelling at the end of an axon where neurotransmitter molecules are released onto a target cell across a synapse

factors under homeostatic control

temperature, pH, fluids, gases, nutrients, electrolytes, hormones

define "polarized state of cells"

the cell is POLARIZED because it exhibits a resting membrane potential

axon hillock

the cone-shaped area on the cell body from which the axon originates -where action potentials start

axon terminal

the endpoint of a neuron where neurotransmitters are stored

axon

the extension of a neuron, ending in branching terminal fibers, through which messages pass to other neurons or to muscles or glands

action potential propagation

the movement of an action potential along an axon; in myelinated axons, it occurs via saltatory conduction -continuous is like the space bar, saltatory like the tab key

somatosensory cortex

the sensory homunculus -this map depicts the relative proportion of the sensory receptors in the various parts of the body

gray matter

unmyelinated axons

occipital lobe

visual cortex and visual association area

what can pass freely through blood-brain barrier?

water, lipid soluble materials lipid soluble: oxygen, carbon dioxide, caffeine, nicotine, steroid hormones, alcohol, barbiturates, some antihistamines

define resting membrane potential

when a cell is at rest (unstimulated), the voltage that exists across the plasma membrane is the resting membrane potential

define feedforward system

★ controlled variable ➞ monitored by receptors ➞ control center ➞ effectors ➞ prepare for change ★ body is "looking forward," anticipatory sequence of events

positive feedback loop

★ sequence of events that promotes/reinforces the change ★ example of cervix stretching and smooth muscle contractions during labor

negative feedback loop

★sequence of events that negates/reverses the change ★ example of elevated blood pressure

protein component of cell membrane

✢ integral = pass all the way through ✢ peripheral ✢ glycoproteins

define peripheral nervous system (PNS)

✷ all nervous system outside the CNS ✷ cranial nerves connect brain to body: 12 pairs ✷ spinal nerves connect spinal cord to body: 31 pairs ✷ extensive networks of sensory receptors and wiring to effectors

define EFFERENT division

✷ somatic nervous system: connects to skeletal muscle ✷ autonomic nervous system: connects to all other tissues ➞ sympathetic: fight or flight activities ➞ parasympathetic: rest and digest activities ➞ enteric: gastrointestinal tract