physio1: week 1
DESCRIPTION
Semester 1 - Physiology - Week 1TRANSCRIPT
Semester 1: Physiology
Body Fluid Compartmentsand
Introduction to Action Potentials
Week 1
Compartments TBW (total body water) = 0.6BW (body
weight) ICF (Intracellular fluid) = 0.4BW ECF (Extracellular fluid) = 0.2BW
Interstitial: 0.75ECF Plasma (blood): 0.25ECF
Capillary wall separates Interstitial and Plasma sub-compartments
T-I-E = 60-40-20
Expansion and ContractionECF ICF Hct = RBC vol/blood vol
Hct ~ ICF/ECF
Isoosmotic volume expansion
↑ - ↓
Isoosmotic volume contraction
↓ - ↑
Hyperosmotic volume expansion
↑ ↓ ↓
Hyperosmotic volume contraction
↓ ↓ -
Hypoosmotic volume expansion
↑ ↑ -
Hypoosmotic volume contraction
↓ ↑ ↑
Tonicity
Determining Tonicity Need EFFECTIVE OSMOLYTE Effective osmolyte = solute that can't
cross the cell membrane; impermeant Sucrose
Ineffective osmolyte = permeable solute Urea
π = σ(nCRT) π = Osmotic pressure
σ = reflection coefficient (0-1)
0 = ineffective osmolyte 1 = impermeant
N = dissociable particles C = total [solute] R = gas constant T = Kelvin
Determining Tonicity
Synaptic Transmission Electrical transmission:
Gap junction (for neuron synchronization) 6 connexins = 1 connexon = ½ gap jxn Can be bi-directional Modulated by:
pH Neurotransmitters (synthesized in RER,
Golgi) Ca2+
Synaptic Transmission Chemical Transmission:
Pre and post-synapse instead of gap jxn
Unidirectional Metabotropic receptors: slow
response via intracellular proteins) Ionotropic receptors: fast response
via depol/hyperpol ion channels
Major Neurotransmitters Acetylcholine (Ach) Excitatory: Glutamate Inhibitory: GABA and Glycine (in vesicles) Amines:
Dopamine Norepinephrine/Epinephrine Histamine Seratonin
Neuron ion content
Depolarization/Action Potential Gates:
M-gate = activation gate
H-gate = inactivation gate (plug)
N-gate = slow-closing K+ channel
Temporal/Spatial Summation → Threshold
EPSP depolarization (Na+)
IPSP hyperpolarization (Cl-)
At resting state: M-gate closed, H and N-gates open
Depolarization: All gates open
Repolarization: H-gates close
After absolute refractory period: All gates closed
Love,Julie and Jenesha