Cell physiology - part 2 Flashcards
excitation (ions)
increase Na+ and Ca+
inhibition (ions)
increase K+ and Cl-
excited area
depolarised
more positive inside
resting area
polarised
more negative inside
saltatory conduction
impulses jump Schwann cells from node to node of Ranvier, faster
what are nerves made up of
neuroglia/ glia
epineurium
perineurium
endoneurium
neuroglia/ glia
non-neural cells maintain homeostasis by forming myelin (insulate, supply O2, hold neuron in place)
epineurium
dense sheath of connective tissue covers each nerve
perineurium
layer surrounds bundles of axons
endoneurium
cover surrounding each fibre
EPSP
excitatory post synaptic potential
depolarisation
glutamate, acetylcholine
Na+ in, K+ out
IPSP
inhibitory post synaptic potential
hyperpolarisation
GABA, glycine
Cl- or K+ in
summation
combination of EPSP and IPSP
EPSP-IPSP cancellation
cancel each other out
EPSP spatial summation
EPSP from different neurons trigger threshold point
EPSP temporal summation
two EPSP from same neuron trigger threshold point
composite post synaptic potential
all EPSPs and IPSP occur at the same time
3 types of muscle
cardiac muscle
smooth muscle
skeletal muscle
cardiac muscle
branched, unaligned fibres
gaps between allow for contraction
gap junction - exchange of small molecules
desmosomes (anchoring junction) - mechanical strength, keratin
smooth muscle
spindle shaped, non-striated
types of skeletal muscle
red muscle
white muscle
mixed muscle
skeletal muscle
myofibrils (contractile fibres) are striated, aligned
red muscle
skeletal muscle
highly vascular, many mitochondria and myoglobin
aerobic
slow contractility
white muscle
skeletal muscle
not very vascular, not many mitochonria and myoglobin
anaerobic
faster contractility
titin filaments
elastic protein chain keep filaments aligned
syncytium
multicellular cell from fusion of many unicellular cells structtural syncytium - skeletal muscle function syncytium - cardiac and smooth muscle
phases of muscle contraction
contraction is depolarisation excitation stimulates Na+ open Ca2+ open, Ca2+ in Ca2+ induce receptors on sarcoplasmic reticulum (SR) to secrete more Ca2+ (positive feedback) Ca2+ stimulate contractile apparatus
phases of muscle relaxation
relaxation is repolarisation
Ca2+ reuptake into sarcoplasmic reticulum (SR)
Na+/ Ca2+ exchanger (NCX): 2Na+ in, 1Ca2+ out
Na+/ K+ ATPase: 3Na+ out, 2K+ in
activation of K+ channels
control of muscles
Ca2+ homeostasis from internal stores in sarcoplasmic reticulum (SR)
latent period
time between stimulus and contraction
excitation of muscles
twitch - single muscle contraction
wave summation - muscle does not completely relax between successive stimulations
incomplete tetanus - partial relaxation between increased frequency of stimulations
complete tetanus - no relaxation, complete contraction, maximal contraction
