Welcome to SPEP 2009!

Welcome toSPEP 2009!

The University of Cincinnati

Heather HaleElise Demitrack

Getting to know you…

• Name• School• Field of interest

Key Terms

• Physiology– Study of Organ function– Regulation/Interaction of organ systems

• Homeostasis– Body performs functions to maintain

constituents of extracellular fluid– Ability to maintain constant internal

environment

• “Steady-state” (equal mixing)

Units

• Mass % (g%) = gram amount per 100 mL (1dL)

• Equivalent (Eq) = gram amount of one mole of a substance divided by it’s valence– i.e. 1Eq of Ca2+ is 40 gm / 2

• Osmoles = # particles released into solution when solute is dissolved in H2O– Osmolar = 1 Osmole/mole dissolved in 1L H2O– Osmolal = 1 Osmole/mole dissolved in 1kg H2O

• One gram-molecular weight of any substance represents and consists of 6 x 1023 molecules

Physiology I

Membrane Physiology

Heather HaleJune 23, 2009

The Plasma Membrane

• Lipid bilayer• Key Constituents:

– Phospholipids• Amphipathic (polar head & non-polar tails)• Fluidity

– Cholesterol• Rigidity

– Glycoproteins (protein + carbohydrate)• “Float” throughout bilayer• Forms receptor substances (glycocalyx)

Head group

Hydrocarbon tail

http://www.cytochemistry.net/Cell-biology/membrane_intro.htm

Membrane Permeability

• Selective!• Simple Diffusion• Rate depends on

molecule’s:– Lipid solubility– Size– Charge

• Assisted by:– Ion channels– Transporters

Crucial for creating an

electrochemical gradient!

http://en.wikipedia.org/wiki/Semipermeable_membrane

Selective Permeability

Plasma Membrane Proteins

• Integral– Permanently associated with

membrane– Transmembrane: spans entire

bilayer

www.ultranet.com/~jkimball/BiologyPages/C/CellMembranes.html

• Peripheral– Associate with

bilayer or another protein

– Temporarily attached

Summary: Plasma Membrane

Membrane Proteins: Channels

• Spans bilayer to form “pore”

• Moves substances across bilayer

• Gating:– Selectivity!– Ligand-gated– Mechanically gated– Voltage-gated

Passive transport!

Membrane proteins: Transporters• “Carrier” proteins

• Transport specific substance across bilayer (selective!)

• Channel changes shape/orientation

Active transport!

http://phy.asu.edu/phy598-bio/D5%20Notes%2006.htm

Types of Transporter Proteins

http://library.thinkquest.org/C004535/cell_membranes.html

Symport videohttp://www.biologie.uni-hamburg.de/b-online/library/biology107/bi107vc/fa99/terry/images/SymporA.gif

Membrane Proteins: Enzymes• Catalyze reactions inside/outside cell

• Associated with membrane to increase efficiency

http://www.biochem.arizona.edu/classes/bioc462/462b/Miesfeld/Photosynthesis.html

• Protein active site (intracellular or extracellular) catalyzes reactions

Examples of Membrane Proteins• Channels: Ca2+ and Na2+ channels

• Transporters:– Proteins transporters– Glucose transporters

• Enzymes: Mitochondrial membrane proteins

Movement Across Plasma Membrane

• Transport of material across bilayer

• Can be direct (non-facilitated)

• Some requires proteins:– Diffusion (facilitated)– Active transport (energy!)

Passive Movement

• No cell energy required!

• Simple diffusion– [high] [low]– Based on molecule‘s

properties– Gases, nutrients, ions

• Limited by diffusion rate of molecule!

http://www.indiana.edu/~phys215/lecture/lecnotes/diff.html

No proteins required!

Passive Movement of Water

• Movement of H2O across cell

• Moves from [H2O]high [H2O]low

• H2O keeps osmotic pressure equal across membrane

http://www.indiana.edu/~phys215/lecture/lecnotes/diff.html

H2O moves toward

compartment with high [solute]

Solutions & Osmotic Pressure

• Solutions– Isotonic: equal [solute] inside/outside– Hypotonic: low [solute]; H2O moves out– Hypertonic: high [solute]; H2O moves in

• Osmotic Pressure– Required to stop osmotic H2O movement– Determined by # particles/unit volume– Osmole = # particles in 1 gram (MW) of un-

dissociated solute

Pressure & Water Movement

• Influenced by two forces– Hydrostatic pressure: caused by

gravity on a column of fluid– Hydraulic pressure: caused by action

of a pump (active!)

• Osmotic pressure = only pressure to initiate water flow in/out of cell

H2O moves from Phigh to Plow

Osmotic Pressure

• Calculated osmotic pressure (π = CsRT)

• Cs = osmolar concentration• R = universal gas constant• T = absolute temperature• (RT = 22.4 ATM/osmole at 37˚C)

• Effective osmotic pressure:– Depends on permeability of

membrane to specific solute

ECF and ICF have [osmotic] = 300 mOs/L

Osmotic Pressure

• Fig A: semipermeable membrane– Solute cannot pass– Pos will equal the

Phydrostatic as water flow into tube

• Fig B: solute-permeable membrane– Solute equilibrates– Effective Pos of solution

is zero

Passive Movement: Facilitated• Requires

membrane proteins!

• Forms water-filled pore

• Solutes move down [conc] gradient (high low)

• Examples:– Glucose transport– K+, Na+, Cl- transport

Active Movement: 1˚ Transport

• Requires cellular energy!

• Transporters bind ATP– Hydrolysis of ATP to ADP + Pi

– Drives transport of solute against concentration gradient!

• Examples:– Na+/K+ ATPase pump– Ca2+ ATPase

Active Movement: Na+/K+ Pump

videohttp://images.google.com/imgres?imgurl=http://student.ccbcmd.edu/~gkaiser/biotutorials/eustruct/images/sppump.gif&imgrefurl=http://student.ccbcmd.edu/~gkaiser/biotutorials/eustruct/sppump.html&h=290&w=290&sz=515&hl=en&start=1&um=1&tbnid=RE2RGHk1UT

Active Movement: 2˚ Transport

• Uses energy of a “driving ion” moving down [conc] gradient to move a 2nd molecule against [conc] gradient

• Driving ion usually Na+ using gradient created by the Na+/K+ pump

http://courses.cm.utexas.edu/jrobertus/ch339k/overheads-2/ch12_Na-gluc-trans

Examples: -Na+/Ca2+ exchanger -Na+/glu transporter

Active Movement: Bulk Transport• Endocytosis: transport into cell

– Phagocytosis = ingest large particles– Pinocytosis = ingest small vesicles– Receptor-mediated ingestion

• Exocytosis: transport out of cellhttp://upload.wikimedia.org/wikipedia/commons/thumb/1/1a/Endocytosis

Physiology I

Body Fluid SpacesHeather HaleJune 24, 2008

Body Fluid Spaces

• The human body is mostly water• Total H2O content of the human

body = 45-60% of body weight

• Total Body Water (% of body weight)– Males: 60% (ages 17-34)

54% (ages 50+)

– Females: 55% (ages 17-34)46% (ages 50+)

Major Body Fluid Spaces

• Two major “compartments”– Intracellular fluid (ICF):

• fluid contained within cells• Accounts for 40% of body fluid weight

– Extracellular fluid (ECF):• fluid outside of the cell• Accounts for 20% of body fluid weight

• Total body water = ICF + ECF


• The 60, 40, 20 rule– 60 = All fluid is 60% of total body weight– 40 = ECF is 40% of body weight– 20 = ICF is 20% of body weight

i.e. 70kg × 0.4 = 28 L of ICF fluid


• ECF is subdivided even further:– Plasma space = 5% of total body

weight– Interstitial fluid (ISF) = 15% of total

body weight

• ISF = ultrafiltrate of plasma

Body Fluids: Hematocrit (Hct)• Ratio of red

blood cell (RBC) volume to whole blood volume

• Hct is typically 40% of whole blood volume

• Whole blood volume = 7-9% of body weight (about 6 L)

Hct = (vol)RBC

(vol)whole blood

1 - Hct = (vol)plasma

(vol)whole

blood

Body Fluids: Cations/Anions

• Total [Osmolar] = 280-296 mOs/L

• Na+ = 13-145 mEq/L• Cl- = 100-106 mEq/L• Ca2+ = 4.3-5.3 mEq/L• Glucose = 70-110 mg%• Total protein = 6-8 g%

Learn these values!

Body Fluids: Cations/Anions

• ECF is high in Na+ & Cl-

• ICF is high in K+

Body Fluid Space Measurements

• To estimate the size of body fluid spaces, use a dye indicator dilution– Based on conservation of mass principle– [conc] vol = mass

• Only applicable during steady-state

• No loss/gain of substance during measurementC1 V1 = C2 V2 V2 = (C1 V1) / C2

Body Fluid Spaces: Fick Principle

• If some solute is lost/gained:– C1 V1 = C2 V2 (+ amount gained)

– or C1 V1 = C2 V2 (- amount lost)

• Analysis represents Fick Principle

• Commonly used to measure blood flow or cardiac output


• 3 component system (plasma, ISF, ICF)

• Inject substances into plasma

• Assumptions– Equal amnt x, y, z– x, y, z not present

before injection


• Capillaries– separate

plasma/ISF– Permeable to y and

z but not to x

• Cell membrane– Separate ISF/ICF– Permeable to z only


• Volume distribution of x = plasma

• Volume distribution of y = plasma + ISF

• Volume distribution of x = ECF + ISF

Body Fluid Spaces: Markers

• Plasma fluid markers (“x”)– Do not cross capillaries– Examples:

• Radioiodinated serum albumin• Evan’s Blue (dye that binds albumin)• RBCs with radioactive iron or chromium


• ECF markers (“y”)– Represents plasma + ISF– Cross capillary but not cell

membrane– Examples:

• Isotopic Cl- or Na+• Inulin• Mannitol


• Markers for total body water (“z”) must be permeable to both capillaries and cell membranes

• Examples:– 3H water (tritiated “heavy” water)– Urea (carbon labeled, or tritiated)– Lipid soluble substances

Capillary Fluid Movement

• Capillaries separate plasma from ISF

• ECF ions move across capillaries between plasma and ISF

• But, proteins are restricted to plasma– Creates osmotic pressure ~15-25

mmHg– This is the colloid osmotic pressure

Starling’s Law of the Capillary

• Principle of pressure differences• Pressures:

– Reabsorptive forces:• Capillary colloid osmotic pressure• ISF hydrostatic pressure

– Filtration forces:• Capillary blood pressure• ISF colloid osmotic pressure

FM = Kf [(BPcap + COPISF) - (COPcap + HPISF)]

Capillary Fluid Movement

FM = Kf [(BPcap + COPISF) - (COPcap + HPISF)]

Reabsorption

Reabsorption

Filtration

Filtration

Contact Info

• Email: [email protected]• Lab location: Health professionals

BuildingRoom 234

(off of Eden Ave, across from Eden Garage and MSB)

Supplementary Figures




Documents

Welcome to SPEP 2009!