animal mt 1 Flashcards
what is the resting potential value of the membrane?
-65 mV
what two refractory periods cause an action potential to be unidirectional?
1) absolute refractory period - Na channels inactivate after use
2) relative refractory period - hyperpolarization drives voltage below resting potential and requires a stronger stimuli to reach threshold
what is locomotion?
an animal moving itself based on its own power
how does an action potential trigger muscle contraction?
- action potential triggers release of ACh into synaptic cleft
- ACh opens ligand channels by binding to postsynaptic receptors
- action potential in muscles is triggered
- action potential propagates into T-tubule channels in muscle
- action potential moves from T-tubules into sarcoplasmic reticulum, opening Ca channels
- Ca ions bind to troponin freeing up actin for myosin to bind
what are the main characteristics of cardiac muscle?
- striated + branched
- few nuclei
- involuntary movement
- sarcomeres
what happens when a synapse is used repeatedly?
signal becomes stronger over time and memories become more common (synaptic plasticity)
what effect did neurotoxins have on Na/K ion channels?
Na: blocked ion flow
K: not affected
what two hormones control the movement within the digestive system?
- ACh (parasympathetic “rest and digest”) activates contraction
- epiniphrine (sympathetic “fight or flight”) inhibits contraction
define learning
enduring change in behaviour due to a prior experience
what are the four parts of the brain?
- cerebellum
- cerebrum
- brain stem
- diencephalon
what is an integral/transmembrane protein?
a protein that has segments that face both the inside and outside of the plasma membrane
how do actin and myosin initiate muscle movement?
- ATP binds to myosin and releases the head from actin
- ATP –> ADP, myosin head straightens out
- myosin reaches forward and binds to a new actin subunit, head curls back to original position
- ADP released and myosin is open for new binding
what were three key findings from patch clamping experiments?
- voltage channels are either open or closed at a given time
- Na channels open quickly after depolarization and creates a positive feedback loop for more Na to enter
- K channels open with delay and then alternate between open and closed until hyperpolarization
what are the two divisions of the autonomic system?
1) parasympathetic - “rest and digest”
2) sympathetic - “fight or flight”
(roughly) what is the equilibrium potential for sodium?
60 mV
what are the three components of the cytoskeleton?
- actin/microfilaments (muscle contraction)
- microtubules (chromosome division)
- intermediate filaments (cell structure)
what are inhibitory post synaptic potentials (IPSP)?
hyperpolarization of post synaptic membrane as a result of neurotransmitter activity leading to a decreased chance of action potentials
(roughly) what is the equilibrium potential for potassium?
-90 mV
describe saltatory conduction
- as an action potential propagates down an axon, it loses momentum in the form of charge
- once potential reaches nodes of ranvier, ion channels add more charge, pushing potential further down axon
what factors affect the magnitude of a postsynaptic response?
- types of receptors
- amount of NT released
- how long NT stays in cleft
- number of receptors in post synaptic neuron
what are the two subsystems of the efferent division?
1) somatic - voluntary skeletal response
2) autonomic - involuntary organ response
how does the troponin-tropomyosin complex affect myosin and how does calcium fix this?
- complex blocks myosin binding sites on actin
- calcium ions bind to complex and frees up binding sites
what happens during repolarization?
certain ion channels close while others open and membrane regains negative charge, brings charge back down to resting potential
what are the main characteristics of skeletal muscle?
- striated + unbranched
- many nuclei
- voluntary movement
- sarcomeres
how does kinesin help in cell movement?
uses ATP to grapple and pull vesicles forward along a microtubule
describe the differences between voluntary and involuntary muscles
voluntary muscles - move via signals from somatic divison (conscious movement)
involuntary muscles - move via signals from autonomic division (unconscious movement)
what are the 3 parts of a neuron and their roles?
dendrites: recieves signals from axons
cell body: integrates signals from dendrites
axons: passes signals from cell body to dendrites
what does the prefrontal cortex do?
creates new synaptic branches (memory retention) or breaks down synapses (losing memory)
what are excitatory post synaptic potentials (EPSP)?
depolarization of post synaptic membrane as a result of neurotransmitter activity leading to an increased chance of action potentials
what are the lobes of the cerebral hemispheres?
- frontal
- parietal
- temporal
- occipital
what are the two types of active transport and what are their main characteristics?
primary transport - pumps powered by ATP used to move against concentration gradient
secondary transport - cotransporters (symporters/antiporters) used to move against concentration gradient
what happens during hyperpolarization?
membrane becomes more negative than resting potential
how do voltage channels work?
when membrane voltage shifts away from resting membrane and hits threshold, channels will either open or close in response
what molecules can easily pass through the membrane?
small nonpolar molecules (O2, CO2, N2 etc)
describe briefly how an action potential propagates down an axon
- Na ions from an action potential enter through channels as membrane depolarizes and repels positive charges away while attracting negative charges
- positive charges accumulate and cause depolarization further down axon
- new depolarization triggers more Na ions to enter and triggers another action potential
what are the two types of passive transport and what are their main characteristics?
diffusion - movement via concentration gradient
facilitated diffusion - use of channel proteins (allows ions through) or carrier proteins (morphs to bind to ions) without ATP
what is the relative refractory period?
phase during hyperpolarization where neuron requires more depolarization to reach threshold and initiate an action potential
what are the four themes of physiology?
- processes obey physical and chemical laws
- processes are shaped by evolution
- processes are usually regulated
- processes are integrated
what are the main characteristics of smooth muscle?
- unstriated + unbranched
- no nucleus
- involuntary movement
- no sarcomeres
what two filaments make up the sarcomere?
actin (thin filaments) and myosin (thick filaments)
what are peripheral membrane proteins?
proteins bound to the plasma membrane and do not pass through
what molecules require help passing through the membrane?
ions (Cl-, K+, Na+)
what are the two divisions of the PNS?
1) afferent division - sensory information
2) efferent division - motor information
what is an equilibrium potential?
the voltage at which an ion reaches equilibrium
what are the two types of cells found in myelin sheaths?
schwann cells (PNS) and oligodendrocytes (CNS)
define a memory
retained information from learning
what happens when the permeability of an ion increases?
the resting membrane potential shifts towards the ion’s equilibrium potential
how do drugs affect neurotransmitters?
can affect release of NT, uptake of NT and blockage of receptors
what happens during depolarization?
ion channels close and membrane loses negative charges, becoming more positive and increasing potential to +40 mV
