Transcript Animal Form & Function Physiolog

Animal Form & Function
Physiology
AP Biology
Nerve Impulse Transmission
Resting potential
 More negative inside cell than outside




Why?
Large negatively charged proteins & nucleic
acids
Na+/K+ pumps maintain high [Na+] outside
cell and high [K+] inside cell
Nerve Impulse Transmission
Resting potential
 Membrane potential = -70 mV

Nerve Impulse Transmission
Depolarization
 Stimulus causes Na+ gates to open
 Na+ rushes into cell
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Nerve Impulse Transmission
Repolarization
 Na+ gates close
& K+ gates open
 K+ rushes out of
cell
 High [Na+] inside
cell
 High [K+]
outside cell

Nerve Impulse Transmission
Hyperpolarization
 K+ gates slow to close
 More K+ moved out
than necessary

Nerve Impulse Transmission
Refractory
period
 Na+/K+ pumps
move

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

Na+ out of cell
K+ into cell
Restores resting
potential
distribution of
Na+ and K+
Transmission Across a Synapse
Synapse
 Gap between neurons

Transmission Across a Synapse

Stimulus reaches synaptic end bulb
Transmission Across a Synapse
Ca2+ gates open
 Ca2+ enters end bulb
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Transmission Across a Synapse
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Vesicles with neurotransmitter
migrate to presynaptic membrane
Transmission Across a Synapse

Vesicle fuses with presynaptic
membrane
Transmission Across a Synapse
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Neurotransmitter released into
synaptic cleft
Transmission Across a Synapse

Neurotransmitter diffuses across
cleft
Transmission Across a Synapse

Neurotransmitter binds to receptor
protein
Transmission Across a Synapse

Postsynpatic neuron depolarizes
Muscle Contraction

Sliding filament model
Muscle Contraction
Sliding filament model
 Depolarization of muscle causes
sarcoplasmic reticulum to release Ca2+

Muscle Contraction
Sliding filament model
 Ca2+ exposes binding sites on actin
 Myosin heads bind to actin
 Cross bridges form

Muscle Contraction
Sliding filament model
 Myosin heads lose ADP + P
 Myosin heads change shape
 Actin pulled toward center of sarcomere
 Muscle contracts

Muscle Contraction
Sliding filament model
 ATP binds to myosin heads
 Cross bridges break
 Muscle relaxes
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Muscle Contraction

Sliding filament model
Steroid Hormone

Steroid hormone
enters cell
Steroid Hormone
Steroid hormone
enters cell
 Binds to receptor
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Steroid Hormone
Steroid hormone
enters cell
 Binds to receptor
 Hormonereceptor complex
enters nucleus
 Causes
transcription

DNA transcribed
RNA translated
Protein Hormone

Protein hormone
too big to enter cell
Protein Hormone
Protein hormone
too big to enter cell
 Binds to receptor

Protein Hormone
Protein hormone
too big to enter cell
 Binds to receptor
 Activates enzyme

Protein Hormone
Protein hormone
too big to enter cell
 Binds to receptor
 Activates enzyme
 Enzyme used to
make cyclic AMP

Protein Hormone
Protein hormone
too big to enter cell
 Binds to receptor
 Activates enzyme
 Enzyme used to
make cyclic AMP
 Cyclic AMP
targets cell
responses

Kidney
Filtration
 Formation of
filtrate
 Waste, nutrients,
water, ions,
proteins move
from the blood
into the Bowman’s
capsule

Kidney
Reabsorpton
 Nutrients, ions, &
water move from
filtrate back into
blood

Kidney
Secretion
 Ions & wastes
more from the
blood into the
filtrate
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Kidney
Bowman’s capsule
 Filtrate production
 Blood pressure forces
small solutes, water &
ions from blood into
capusule
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Kidney
Proximal convoluted
tubule
 Reabsorption of water,
ions, and all organic
nutrients
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Kidney
Loop of Henle
 Descending limb
 Water reabsorbed
 Wall permeable to water
but not solutes
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Kidney
Loop of Henle
 Ascending limb
 Wall impermeable to
water and solutes
 Cells actively pump Na+
and Cl- out of tubular
fluid

Kidney
Distal convoluted
tubule
 Secretion of ions, acids,
drugs, toxins
 Variable reabsorption of
water and Na+

Kidney
Collecting duct
 Variable reabsorption of
water and ions
 Variable secretion of
water and ions
 Balancing act homeostasis
