Animal Phys Exam 2

diffusion

random movement of solutes from thermal energy (high to low)

electrochemical gradients

ions move based on charge; chemical move based on high to low concentration

membrane potential (Vm)

difference in charge across a membrane

equilibrium potential (Nernst equation)

hypothetical membrane potential where the chemical and electrical gradient are equal in magnitude and opposite in direction

Potential difference = E

difference in voltage between two points

membrane potential = Vm

Difference in voltage across the plasma membrane; always given in terms of voltage inside the cell relative to voltage outside the cell

resting Vm (membrane potential)

Difference in voltage across the plasma membrane when a cell is at rest( not receiving or sending signals)

Graded Potential

A relatively small change in membrane, potential produced by some type of stimulus that triggers the opening or closing of ion channels; strength of graded potential is relative to strength of stimulus

Synaptic potential

Graded potential's produced in the postsynaptic cell response to neurotransmitters binding to receptors

Receptor potential

Graded potential's produced in response to a stimulus acting on a sensory receptor (small charge)

Action potential

A large rapid change in membrane, potential produced by depolarization of an excitable cells plasma membrane to threshold (all or none)

Equilibrium potential

The membrane potential that counters, the chemical forces acting to move on an ion across the membrane there by putting the ion at equilibrium

Threshold potential

The Vm (membrane potential) at which an action potential is initiated

Goldman-Hodgkins-Katz (GHK) Equation

Defines membrane potential when cell is permeable to more than one ion at the same time. We will only consider the effect of Na+ and K+ because these are the dominant ions and the ones that play a really important role in establishing the resting Vm and Vm changes during an action potential

Permeability

Permeability depends on a lot of factors such as solubility temperature. And the units are complex for our sake we will simply think of ions as NOT being permeable through cell membranes, and that changes in permeability and mediated by the opening, or closing of ion specific channels

Resting membrane potential results from a balance between

* activity of Na+/K+ pump
* Relative permeability of the membrane to different ions (determined by presence of ion channels – leak channels in this case)

What mediates membrane permeability?

Changes in membrane permeability are mediated by ion channels

what are the different types of ion channels?

* leak channels
* ligand gated channels
* voltage gated channels

Leak channels

Always open

Ligand gated channels

Closed, but opened by some specific ligand (neurohormone)

voltage gated channels

* Open or close by change in membrane potential
* What makes excitable cells excitable
* Basis for action potential

Action potential

* All or none changes in membrane potential
* Triggered at axon hillock (neurons) & at motor end plate in muscle

The phases of a typical action potential

* Depolarization phase
* Repolarization phase
* Hyperpolarization phase

Depolarization phase

Due to increased Na+ permeability

Repolarization phase

Due to increased K+ permeability

Hyperpolarization phase

Due to increased K+ permeability

Voltage gated Na+ channel

2 gates

* Activation gate
* Inactivation gate

Voltage gated sodium channel - At Rest

Activation, gate closed ; inactivation gate open

voltage gated sodium channel – threshold

Activation gate opens; sodium in

Voltage gated, sodium channels - brief time later

inactivation gate closes; inward Na+ stops

* Gates, do not return to rest configuration until membrane potential drops below threshold

Voltage gated potassium channel

Only one gate

Voltage gated potassium channel – at rest

Gate is closed

Voltage gated potassium channel - thereshold

Gate triggers to open, but occurs slower than sodium activation gate

\* Gate does not close until membrane potential drops below threshold

Conduction of action potential down axon or along muscle membrane (sarcolemma)

* Na+ entry during, AP spreads to adjacent region of the cell, causing it to depolarize to threshold and generate an action potential
* Repeats down axon until reaches, axon terminal

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What does a neuron secrete when triggered by an action potential?

neurotransmitters then secrete neurohormones

soma (cell body)

Contains the nucleus and hold all of the general parts of the cell

axon

Send signals to other neurons muscles or organs

dendrites

Extend away from cell body and receive messages from other neurons at synapses

synapses

* Specialized junctions between neurons
* Enable the dendrites from a single neuron to interact and receive signals from many other neurons

Neural tissue

* neruons and glial cells (all support neruron function in some way)
* Produce myelin, sheath increases actionvpotential velocity; insulation
* schwann cell- PNS
* oligodendrocyte - CNS

What are the main parts of a typical neuron?

* Dendrites
* Soma
* axon hillock
* axon
* axon terminals

Location and function of ligand gated ion channel

* Dendrites
* Soma (deciding if cell will reach threshold)

Location and function of leak gated ion channel

Found everywhere

Location and function of voltage gated ion channel

Only found an axon and axon terminal, concentrated at axon hillock

SSynaptic function

Neurons “talk” to other neurons or effector cells, mainly through chemical synapses (neurons “talk” to effector organs through neuroeffector junctions.).

What are the structural classifications of neurons?

* Multipolar,
* Bipolar
* Pseudo-unipolar

multipolar

Most common, many dendrites, one axon

bipolar

One dendrite, one axon, few; mainly in retina, or olfactory cells

pseudounipolar

primarily found as first order neurons of the sensory system

functional classification of neurons

* afferent
* efferent
* interneuron or integrative
* association
* commissural
* projection

Where do afferent neurons carry information?

toward CNS

Where is interneuron or integrative information processed?

within CNS

Where do efferent neurons carry their information toward?

info from CNS to effectors

Somatic senses

skin; external (temp,pain)

Special senses

smell, sight

Visceral senses

internal; blood pressure, pH, O2, CO2

Cerebral cortex function

Info processing

Basal Nuclei function

movement coordination

Limbic System

emotions

Hippocampus

Memory

Thalamus

Relay of sensory info

Hypothalamus

homeostatic regulation

pituitary (posterior)

homeostatic regulation

Copora Quadrigemina

Reflex processing of visual, auditory ques

Cerebellum

Posture and coordinated movement

Pons

Involved in the regulation of breathing

Medulla Oblongata

Autonomic: HR, blood pressure, breathing

parts of the frontal lobe

* Prefrontal cortex
* premotor cortex
* primary motor cortex
* broca’s area

parts of the parietal lobe

* Somatosensory cortex
* Sensory association areas

Parts of the occipital lobe

* Visual cortex
* Visual association areas

Parts of the temporal lobe

* Auditory cortex.
* Factory cortex
* Wernicke’s area
* Limbic association
* Amygdala
* Hippocampus

Prefrontal cortex

Thought, behavior

premotor cortex

Motor planning

Primary motor cortex

Upper motor neurons send Info down to control lower motor neurons

Broca’s area

Special motor area for speech

Somatosensory cortex

Receive sensory info

sensory association areas

put sensory together with other

Visual cortex

First spot vision goes

Visual association areas

Put Info together

Auditory cortex

Sound

olfactory cortex

Smell

wernicke’s area

Language storage

limbic association areas

* Amygdala.


* Hippocampus

amygdala

Fear and anger

hippocampus

Memory

CCerebellum function

* knows what the plan is and received feedback and compares within cerebellum


* well correct if something has gone wrong, like intention, tremor.

Parietal lobe function

Receives and put a touch, pressure, temperature

White matter

Largely axons with, myelin sheaths

Grey matter

Mostly summer and dendrites (unmyelinated)

Nucleus

Collection of info and CNS

ganglion

Collection of soma and the PNS

N nerve

Bundle of axons in PNS; communicate action potentials (afferent or efferent)

track

Bundle of axons in CNS

Peripheral nervous system (CNS)

afferent info to CNS

Sensation

Anything detected by nervous system

Perception

Conscious process of that sensation

Sensations are detected by

* Sensory Receptors
* Visceral Receptors

Sensory receptors

Structures that detect something, external environment

Visceral receptors

Structures had to text something internal environment