Chapter 5c Membrane Dynamics
Chapter 5c
Feb 24, 2016
Chapter 5c. Membrane Dynamics. The Body Is Mostly Water. Distribution of water volume in the three body fluid compartments 1 liter water weighs 1 kg or 2.2 lbs 70 kg X 60% = 42 liters for avg 154 lb male. Figure 5-25. Aquaporin. - PowerPoint PPT Presentation
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Chapter 5c
Membrane Dynamics
Figure 5-25
The Body Is Mostly Water
• Distribution of water volume in the three body fluid compartments
• 1 liter water weighs 1 kg or 2.2 lbs
• 70 kg X 60% = 42 liters for avg 154 lb male
AquaporinMoves freely through cells by special channels of aquaporin
Figure 5-26
Osmosis and Osmotic Pressure
• Osmolarity describes the number of particles in solution
Volumesequal
Osmotic pressure isthe pressure that must beapplied to B to oppose osmosis.
Volumeincreased
Volumedecreased
Two compartments areseparated by a membrane that is permeable to water but not glucose.
Water moves byosmosis into the moreconcentrated solution.
Glucosemolecules
Selectivelypermeablemembrane
A B
1
3
2
Table 5-5
Osmolarity: Comparing SolutionsHyper / Hypo / Iso are relative terms
Osmolarity is total particles in solutionNormal Human body around 280 – 300 mOsM
Table 5-6
Tonicity
• Solute concentration = tonicity• Tonicity describes the volume change of a
cell placed in a solution
Figure 5-27a
Tonicity
• Tonicity depends on the relative concentrations of nonpenetrating solutes
Figure 5-27b
Tonicity
• Tonicity depends on nonpenetrating solutes only
Figure 5-28
Tonicity
• Tonicity depends on nonpenetrating solutes only
(a)
(b)
(c)
(d)
Cell
Solution
H2O
Plasmolysis and Crenation
• RBC’s
Table 5-7
Osmolarity and Tonicity
Table 5-8
Intravenous Solutions
Electricity Review
1. Law of conservation of electrical charges2. Opposite charges attract; like charges repel
each other3. Separating positive charges from negative
charges requires energy4. Conductor versus insulator
Figure 5-29b
Separation of Electrical Charges
• Resting membrane potential is the electrical gradient between ECF and ICF
(b) Cell and solution in chemical and electrical disequilbrium.
Intracellular fluid Extracellular fluid
Figure 5-29c
Separation of Electrical Charges
• Resting membrane potential is the electrical gradient between ECF and ICF
Figure 5-30
Measuring Membrane Potential Difference
The voltmeter
Cell
The chart recorder
Saline bath
A recording electrode
Input
The ground ( ) or referenceelectrode
Output
Figure 5-31a
Potassium Equilibrium PotentialArtificial cell
(a)
Figure 5-31b
Potassium Equilibrium Potential
(b)
K+ leak channel
Figure 5-31c
Potassium Equilibrium Potential• Resting membrane potential is due mostly
to potassium• K+ can exit due to [ ] gradient, but electrical gradient will
pull back; when equal resting membrane potential
Concentrationgradient
Electricalgradient
(c)
Figure 5-32
Sodium Equilibrium Potential• Single ion can be calculated using the Nernst Equation
• Eion = 61/z log ([ion] out / [ion] in)
150 mM0 mV
15 mM+60 mV
Figure 5-33
Resting Membrane Potential
Extracellular fluid0 mV
Intracellular fluid-70 mV
Figure 5-34
Changes in Membrane Potential
• Terminology associated with changes in membrane potential
PLAY Interactive Physiology® Animation: Nervous I: The Membrane Potential
1Low glucose levels in blood.
No insulinsecretion
Metabolismslows.
ATPdecreases.
ATPMetabolismGlucose
Cell at restingmembrane potential.No insulin is released.
KATP
channels open.
Insulin in secretory vesicles
K+ leaks out
of cellVoltage-gated Ca2+ channel closed
GLUT transporter
(a) Beta cell at rest
2 3 4 5
Figure 5-35a
Insulin Secretion and Membrane Transport Processes
1Low glucose levels in blood.
Glucose
(a) Beta cell at restFigure 5-35a, step 1
Insulin Secretion and Membrane Transport Processes
1Low glucose levels in blood.
Metabolismslows.
MetabolismGlucose
GLUT transporter
(a) Beta cell at rest
2
Figure 5-35a, steps 1–2
Insulin Secretion and Membrane Transport Processes
1Low glucose levels in blood.
Metabolismslows.
ATPdecreases.
ATPMetabolismGlucose
GLUT transporter
(a) Beta cell at rest
2 3
Figure 5-35a, steps 1–3
Insulin Secretion and Membrane Transport Processes
1Low glucose levels in blood.
Metabolismslows.
ATPdecreases.
ATPMetabolismGlucose
KATP
channels open.
K+ leaks out
of cell
GLUT transporter
(a) Beta cell at rest
2 3 4
Figure 5-35a, steps 1–4
Insulin Secretion and Membrane Transport Processes
1Low glucose levels in blood.
No insulinsecretion
Metabolismslows.
ATPdecreases.
ATPMetabolismGlucose
Cell at restingmembrane potential.No insulin is released.
KATP
channels open.
Insulin in secretory vesicles
K+ leaks out
of cellVoltage-gated Ca2+ channel closed
GLUT transporter
(a) Beta cell at rest
2 3 4 5
Figure 5-35a, steps 1–5
Insulin Secretion and Membrane Transport Processes
1
Glycolysisand citric acid cycle
ATP
Ca2+ signal triggersexocytosis and insulin is secreted.
Ca2+
Ca2+
High glucose levels in blood.
Metabolismincreases.
ATPincreases.
Glucose
Cell depolarizes andcalcium channelsopen.
KATP channels close.
Ca2+ entry acts as anintracellularsignal.
GLUT transporter
(b) Beta cell secretes insulin
2 3 4 5
6
7
Figure 5-35b
Insulin Secretion and Membrane Transport Processes
1High glucose levels in blood.
(b) Beta cell secretes insulinFigure 5-35b, step 1
Insulin Secretion and Membrane Transport Processes
Glucose
1
Glycolysisand citric acid cycle
High glucose levels in blood.
GLUT transporter
(b) Beta cell secretes insulin
2
Figure 5-35b, steps 1–2
Insulin Secretion and Membrane Transport Processes
Glucose
Metabolismincreases.
1
Glycolysisand citric acid cycle
ATP
High glucose levels in blood.
GLUT transporter
(b) Beta cell secretes insulin
2 3
Figure 5-35b, steps 1–3
Insulin Secretion and Membrane Transport Processes
Glucose
Metabolismincreases.
ATPincreases.
1
Glycolysisand citric acid cycle
ATP
High glucose levels in blood.
KATP channels close.
GLUT transporter
(b) Beta cell secretes insulin
2 3 4
Figure 5-35b, steps 1–4
Insulin Secretion and Membrane Transport Processes
Glucose
Metabolismincreases.
ATPincreases.
1
Glycolysisand citric acid cycle
ATP
Ca2+
High glucose levels in blood.
Cell depolarizes andcalcium channelsopen.
KATP channels close.
GLUT transporter
(b) Beta cell secretes insulin
2 3 4 5
Figure 5-35b, steps 1–5
Insulin Secretion and Membrane Transport Processes
Glucose
Metabolismincreases.
ATPincreases.
1
Glycolysisand citric acid cycle
ATP
Ca2+
Ca2+
High glucose levels in blood.
Cell depolarizes andcalcium channelsopen.
KATP channels close.
Ca2+ entry acts as anintracellularsignal.
GLUT transporter
(b) Beta cell secretes insulin
2 3 4 5
6
Figure 5-35b, steps 1–6
Insulin Secretion and Membrane Transport Processes
Glucose
Metabolismincreases.
ATPincreases.
1
Glycolysisand citric acid cycle
ATP
Ca2+ signal triggersexocytosis and insulin is secreted.
Ca2+
Ca2+
High glucose levels in blood.
Cell depolarizes andcalcium channelsopen.
KATP channels close.
Ca2+ entry acts as anintracellularsignal.
GLUT transporter
(b) Beta cell secretes insulin
2 3 4 5
6
7
Figure 5-35b, steps 1–7
Insulin Secretion and Membrane Transport Processes
Glucose
Metabolismincreases.
ATPincreases.
Summary
• Mass balance and homeostasis• Law of mass balance• Excretion• Metabolism• Clearance• Chemical disequilibrium• Electrical disequilibrium• Osmotic equilibrium
Summary
• Diffusion• Protein-mediated transport• Roles of membrane proteins• Channel proteins• Carrier proteins• Active transport
Summary
• Vesicular transport• Phagocytosis• Endocytosis• Exocytosis
• Transepithelial transport
Summary
• Osmosis and tonicity• Osmolarity• Nonpenetrating solutes • Tonicity
• The resting membrane potential• Insulin secretion
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