BIOL207 Lecture Notes - Lecture 1: Endocytosis, Facilitated Diffusion, Membrane Potential
27 May 2018
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Department
Course
Professor
September 17, 2013
PEDS 101 – Human Physiology
Chapter 5: Membrane Dynamics
Chapter 5 Overview:
• Homeostasis and body fluid compartments
• Osmosis and tonicity (on your own; page 132-139) → what is it, why is it important. Not
calculations
→
how it contributes to homeostasis
Transport processes (membrane properties)
• Diffusion
• Protein-mediated transport
• Vesicular transport (on your own; page
155-157) → brief
• Epithelial transport (PEDS 103)
• Resting membrane potential (later with
chapter 8)
Concept Check:
• Osmosis and tonicity - Page 139 (#6-#10)
• Vesicular transport - Page 157 (#27-#29),
Page 160 (#30-#33)
→
Diffusion – movement of higher [] gradient to lower [] gradient
→
suggests crossing
membrane. Ex: ions, CO2, O2
Next 3 images say the same thing, just different illustrations.
Osmotic equilibrium – equal pressure
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September 17, 2013
Homeostasis ≠Equilibrium:
• Homeostasis = staility of ody’s iteal eioet staility of ECF
- ECF and ICF exist in state of dynamic disequilibrium
• Osmotic (water and solute)
• Chemical (Fig 5.1 d)
• Electrical (resting membrane potential)
Na+ and K+, which is the:
• Major ECF ion? Sodium
• Major ICF ion? Potassium
• Where is the higher concentration of proteins (ECF or ICF)? ICF has highest protein [] → Ex:
when you sprain ankle there is swelling in interstitial compartment (no proteins) →
wherever proteins go H2O will follow
Does movement of
transfer require
energy? No energy =
diffusion going high to
low
Electrical disequilibrium – different
electrical charged
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September 17, 2013
A&P Flix Membrane Transport:
→ In order for us to use the molecules and energy we get from food, we must transport them across
cell membranes.
Movement across membranes:
• Materials can move freely WITHIN compartment but movement BETWEEN compartments is
restricted by CELL MEMBRANE
• Movement across depends upon properties of CELL MEMBRANE and SUBSTANCE (size and
solubility)
• “Seletively permeale” (permeable vs. impermeable)
- Solubility: with respect to lipid bilayer (with or without protein carrier)
- Selectively permeable: allowing some substances through, but not all
Who gets across? (Most soluble)
• Water, oxygen, carbon dioxide and lipids move easily across most membranes
- no energy, no protein = diffusion. Governed by [] gradient
→
high to low []
• Ions, most polar molecules and very large molecules (ex: proteins) cannot cross easily
• Most small and lipid soluble molecules can easily cross (simple diffusion)
Simple → does’t euie potei
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find more resources at oneclass.com
Document Summary
Chapter 5 overview: homeostasis and body fluid compartments, osmosis and tonicity (on your own; page 132-139) what is it, why is it important. Not calculations how it contributes to homeostasis. Transport processes (membrane properties: diffusion, protein-mediated transport, vesicular transport (on your own; page. 155-157) brief: epithelial transport (peds 103, resting membrane potential (later with chapter 8) Concept check: osmosis and tonicity - page 139 (#6-#10, vesicular transport - page 157 (#27-#29), Diffusion movement of higher [] gradient to lower [] gradient suggests crossing membrane. Next 3 images say the same thing, just different illustrations. Homeostasis equilibrium: homeostasis = sta(cid:271)ility of (cid:271)ody"s i(cid:374)te(cid:396)(cid:374)al e(cid:374)(cid:448)i(cid:396)o(cid:374)(cid:373)e(cid:374)t (cid:894)sta(cid:271)ility of ecf(cid:895) Ecf and icf exist in state of dynamic disequilibrium: osmotic (water and solute, chemical (fig 5. 1 d, electrical (resting membrane potential) Icf has highest protein [] ex: when you sprain ankle there is swelling in interstitial compartment (no proteins) wherever proteins go h2o will follow. No energy = diffusion going high to low.
