Physio 204

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Text Edition (10th/11th/12th) is specified if the figure numbers are DIFFERENT in the editions. If figure numbers are the SAME, then the edition is not specified.

****502 Students: Read this paragraph ****
If you are a 502 student using this guide, this is based on Dr. Rust’s lectures in Physiol 201. Topics may have been covered in more detail in 502 or the coverage or emphasis may have been different since many topics in 502 were taught by other professors- so use your notes and slides along with this guide.

THIS PACKET IS NOT SIGNIFICANTLY MODIFIED FROM SEMESTER TO SEMESTER. THE MATERIAL HERE MAY BE SOMEWHAT DIFFERENT THAN THE COVERAGE IN LECTURE THIS SEMESTER. SO- USE YOUR NOTES AND SLIDES. • Topics that WERE covered in lecture, but are not here, ARE REQUIRED MATERIAL for the Final Exam. This is not meant to replace your slides/notes, but to give you a guide and a place to start. • Topics that were NOT covered in lecture, but that are covered here (or with differing amount of detail here than in lecture), ARE NOT REQUIRED material for the Final Exam. • Again- this is not meant to replace your slides/notes…

Topics I am aware are missing (there may be others): Reproductive Physiology


Homeostasis is the maintenance of relatively stable conditions of the internal environment. The “internal environment” is the extracellular fluid- the fluid outside the cells. The extracellular fluid is comprised of the plasma and the interstitial fluid.

Homeostatic reflex arcs are stimulus response sequences that involve negative feedback and are designed to respond to a change in a variable by bringing the variable back toward normal. Examples of variable regulated by homeostatic reflex arcs are:

Body Temperature
Blood pressure
Arterial PO2 and PCO2
Arterial pH
Plasma Glucose
Plasma Na+, K+, Ca2+
And many more.

See Figure 1-6 (10th), 1-7 (11th), 1-8 (12th) in Vander’s Human Physiology for example of homeostatic reflex response to a decrease in body temperature.


Functions of Membranes:
1. form selective barrier
2. detect chemical messengers at cell surface
3. link adjacent cells together
4. anchor cells to extracellular matrix

Mechanisms for movement across membranes:
1. diffusion- passive movement of solute driven by a concentration gradient 2. osmosis- passive movement of water driven by a concentration (osmolarity) gradient 3. Mediated transport systems

a. Facilitated diffusion: movement requires binding of molecule to a transport protein, but movement is passive, down a concentration gradient b. Active transport: movement requires binding of molecule to a transport protein and movement requires energy and is uphill, against a concentration gradient i. Primary active transport: transport protein directly utilizes ATP to provide energy for uphill transport of molecule(s). Example = Na+/K+ ATPase ii. Secondary active transport: transport protein utilizes energy in the electrochemical gradient of an ion (usually Na+) to move a molecule uphill, against it’s concentration gradient. Examples = Na+/H+ exchanger, Na+/glucose cotransporter. 4. Endocytosis and exocytosis

Membrane Potential refers to the separation of charge across the plasma membrane, measured in millivolts (mV). Inside of cell membrane is negative compared to outside of membrane. A typical Vm (resting membrane potential) for a neuron is -70mV. The membrane potential is determined by the permeabilities of ions and the equilibrium potential for ions that can cross the membrane. Ion flux is determined by concentration gradients and electrical gradients. The most important ion fluxes in terms of resting membrane potential are K+ and Na+. [K+] is greater inside the cell than outside the cell. The concentration gradient is therefore a driving force...
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