PHYL2002 Lecture Notes - Lecture 1: Nucleolus, Glucocorticoid Receptor, Neurochemistry
PHYL2002
Physiology of Cells
Alyssa Santarelli
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Table of Contents
CELL TRANSPORT 3
DIFFUSION: 3
CELL MEMBRANE: 3
MEMBRANE TRANSPORT: 3
VESICLE TRANSPORT: 3
OSMOSIS: 4
MEMBRANE POTENTIAL: 4
FACILITATED DIFFUSION: 5
ACTIVE TRANSPORT: 5
CARRIERS AND PUMP: 6
ABSORPTION OF NUTRIENTS: 6
FAST SIGNALING IN THE NERVOUS SYSTEM 7
INTRODUCTION TO THE NERVOUS SYSTEM: 7
ION CHANNELS: 9
ACTION POTENTIALS: 10
SYNAPTIC TRANSMISSION 13
MUSCLE PHYSIOLOGY 15
SKELETAL MUSCLE: 15
SMOOTH MUSCLE: 18
CARDIAC MUSCLE: 19
SENSORY PHYSIOLOGY 21
SENSORY PROCESSING AND SOMATOSENSATION: 21
CELLULAR BASIS OF HEARING AND BALANCE: 23
CELLULAR BASIS OF CHEMOSENSATION: 24
CELLULAR BASIS OF PHOTOTRANSDUCTION: 25
MOTOR CIRCUITS AND REFLEXES: 27
INTRACELLULAR MESSAGES 28
GPCR AND SECOND MESSENGERS: 28
INSULIN AND PROTEIN KINASES: 30
STEROID HORMONES AND TRANSCRIPTION: 31
FEATURES OF SIGNAL PATHWAYS: 33
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Cell Transport
Diffusion:
• Simple diffusion → uniform spreading out of molecules as a result of
random 3intermingling
• Molecules move from high to low concentration
• Movement is random for each individual molecule
• Amount of substance moving over time → flow → flux
• Flux from diffusion depends on concentration gradient
• Not very efficient over long distances → usually over short distances very
fast
• Permeability depends on membrane thickness, solubility in lipids and
water, diffusion constant → thickness + diffusion constant + solubility
Cell Membrane:
• Cell membrane is lipid bilayer
• Charged phospholipids face out
• Hydrophobic tails face in
• Selectively permeable
• Governed by transmembrane proteins that form channels/pores
• Almost all cells have aquaporins → water channels
• Water can diffuse into or out of the cell
Membrane Transport:
• Transmembrane proteins flow movement across lipid layer
• Controls permeability to ions, molecules etc.
• Substances that diffuse across the lipid layer → ethanol, carbon dioxide,
oxygen
• Substances that diffuse through a channel/pore → sodium, chloride
• Substances that diffuse through a carrier → glucose → can be active or
passive
• Active transport uses a carrier → uses ATP
• Endocytosis/exocytosis → requires ATP, mainly neurotransmitters
• Channels, carriers and endocytosis/exocytosis are selective and can be
regulated
Vesicle Transport:
• Material is moved into/out of the cell wrapped in membrane
• Endocytosis
o Transport into cell
o Plasma membrane surrounds substance to be ingested
o 2 types
▪ Pinocytosis → smaller molecules
▪ Phagocytosis → larger molecules
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Document Summary
In general water will follow salt/solute movement isosmotic doesn(cid:495)t mean isotonic if the solute can move. If the solute is impermeable isosmotic = isotonic. Inside 140 mm: outside 5 mm. Inside 10 mm: outside 145 mm. Ion channels are selective due to: size of pore, small throat will not let large ions through, electrical charge of chains of amino acids that enter pore, negative charged throat repels anions makes channel cation selection. Ionic basis of action potential: 3 states of na+ channels, resting, activated. Inactivated: 2 states of k+ channels, resting, activated opens after depolarization, both channels are voltage gated, no direct involvement of pump/carriers indirect role for na/k. Increases na+ permeability: inhibitory post-synaptic potential (ipsp) Increases cl- permeability: occur when a neuron signals another neuron, post-synaptic potentials are the change in voltage produced in the post synaptic cell epsp or ipsp.
