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Biol 336 Unit 1 Notes
Human Physiology (San Diego State University)
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Lecture 1: Introduction to Physiology
● Physiology
○ Study of function
○ How does the body work?
○ Conceptual thinking
● Anatomy
○ Study of structure
○ How does it look?
○ Memorization
● Phospholipid bilayer: separates intracellular fluid (inside cell) and extracellular fluid
(saliva, urine, blood)
● Cell membrane: 50% phospholipids and 50% proteins
● Phospholipids
○ Amphipathic: polar heads, non-polar tails
● Factors that regulate membrane fluidity
○ Higher temperatures → higher fluidity
○ More saturated fatty acids → fluidity decreases
○ More unsaturated fatty acids → fluidity increases
● Proteins: integral (transmembrane)
○ 1. Pump (ATP)
○ 2. Gate (drugs)
○ 3. Receptor (hormones)
● Sodium Potassium ATPase
○ Protein pump using ions
■ Cations: positive charge
■ Anion: negative charge
○ 25% energy used in body is used by sodium potassium pump
○ Active Transport
■ ATP → ADP + P + energy
○ Exchange of Na+ and K+
■ 3 Na+ moved out of cell
Downloaded by joshua wesonga ()
, lOMoARcPSD|59939466
■ 2 K+ in
○ Hyponatremia: low salt in blood (less than 135 mmol/L)
■ Hypernatremia: high salt in blood
■ Eunatremia: normal
● Fluid concentration of Na+
○ Na+ outside = 135-145 mmol/L
○ 10x more Na+ outside vs inside the cell
● Fluid concentration of K+
○ K+ outside = 3.5-5 mmol/L
○ 10x more K+ inside vs outside the cell
● Excitability and concentration gradients
○ Excitability: the ability of a cell to send and receive electrical signals across the
plasma membrane
● Clinical application
○ What occurs when the concentration of K+ outside the cell if cells are crushed?
■ Hyperkalemia: death
● Membrane potential
○ Difference: the intracellular minus the extracellular electrical potential
Lecture 2: Neurons and Action Potential
● Resting membrane potential
○ Membrane is more permeable to K+
○ More K+ leaves the cell than Na+ enters
○ Inside of the cell becomes negative
■ Polarized cells
■ Like a battery
○ RMP for humans is -80mv
■ Red blood cells is -60mv
■ Goes to 0 mv right before you die
● Hodgkin-Huxley Nerve Membrane Model
○ Measured time varying sodium conductance and time varying potassium
conductance
○ Won 1961 Nobel Prize in Physiology
● Action potential
○ How our body communicates with 87 billion neurons and the environment
○ When difference in resting membrane potential becomes -50mv → big spike in
electricity occurs
○ All or none
■ Threshold must be reached for an action potential to occur (-50mv)
■ Take away polarity (-80mv to 0mv) is depolarization
● Membrane potential moves from rest to a more positive value
■ Going positive (0mv to +30mv) is overshoot
■ Making the cell polarized again is repolarization
● Membrane potential moves back to resting value
Downloaded by joshua wesonga ()
Biol 336 Unit 1 Notes
Human Physiology (San Diego State University)
Scan to open on Studocu
Studocu is not sponsored or endorsed by any college or university
Downloaded by joshua wesonga ()
, lOMoARcPSD|59939466
Lecture 1: Introduction to Physiology
● Physiology
○ Study of function
○ How does the body work?
○ Conceptual thinking
● Anatomy
○ Study of structure
○ How does it look?
○ Memorization
● Phospholipid bilayer: separates intracellular fluid (inside cell) and extracellular fluid
(saliva, urine, blood)
● Cell membrane: 50% phospholipids and 50% proteins
● Phospholipids
○ Amphipathic: polar heads, non-polar tails
● Factors that regulate membrane fluidity
○ Higher temperatures → higher fluidity
○ More saturated fatty acids → fluidity decreases
○ More unsaturated fatty acids → fluidity increases
● Proteins: integral (transmembrane)
○ 1. Pump (ATP)
○ 2. Gate (drugs)
○ 3. Receptor (hormones)
● Sodium Potassium ATPase
○ Protein pump using ions
■ Cations: positive charge
■ Anion: negative charge
○ 25% energy used in body is used by sodium potassium pump
○ Active Transport
■ ATP → ADP + P + energy
○ Exchange of Na+ and K+
■ 3 Na+ moved out of cell
Downloaded by joshua wesonga ()
, lOMoARcPSD|59939466
■ 2 K+ in
○ Hyponatremia: low salt in blood (less than 135 mmol/L)
■ Hypernatremia: high salt in blood
■ Eunatremia: normal
● Fluid concentration of Na+
○ Na+ outside = 135-145 mmol/L
○ 10x more Na+ outside vs inside the cell
● Fluid concentration of K+
○ K+ outside = 3.5-5 mmol/L
○ 10x more K+ inside vs outside the cell
● Excitability and concentration gradients
○ Excitability: the ability of a cell to send and receive electrical signals across the
plasma membrane
● Clinical application
○ What occurs when the concentration of K+ outside the cell if cells are crushed?
■ Hyperkalemia: death
● Membrane potential
○ Difference: the intracellular minus the extracellular electrical potential
Lecture 2: Neurons and Action Potential
● Resting membrane potential
○ Membrane is more permeable to K+
○ More K+ leaves the cell than Na+ enters
○ Inside of the cell becomes negative
■ Polarized cells
■ Like a battery
○ RMP for humans is -80mv
■ Red blood cells is -60mv
■ Goes to 0 mv right before you die
● Hodgkin-Huxley Nerve Membrane Model
○ Measured time varying sodium conductance and time varying potassium
conductance
○ Won 1961 Nobel Prize in Physiology
● Action potential
○ How our body communicates with 87 billion neurons and the environment
○ When difference in resting membrane potential becomes -50mv → big spike in
electricity occurs
○ All or none
■ Threshold must be reached for an action potential to occur (-50mv)
■ Take away polarity (-80mv to 0mv) is depolarization
● Membrane potential moves from rest to a more positive value
■ Going positive (0mv to +30mv) is overshoot
■ Making the cell polarized again is repolarization
● Membrane potential moves back to resting value
Downloaded by joshua wesonga ()
