20110103 Lecture 1 notes.txt
From Iusmphysiology
- Started here on 01/03/11 at 9AM
- Two lowest of the 5+7 quizzes are dropped.
- Three interim exams account for 60%.
- Very few fail the NBME exam.
- The NBME accounts for 25%.
- Most students perfom same on NBME as on interim exams.
- Must get 70% or better to pass, above the class average is high pass, honors is one SD above class average.
Contents |
[edit] Lecture 1
- We must regulate our functions if we can survive for 70 years of bombardment.
- Claude bernard came up with homeostasis: the resistance to change.
- We can live in dry / wet / cold / hot climeates, etc. because we control our internal environment.
- We have to control gasses, osmotic pressure, etc.
- Bernard also recognized the control of internal temperature in mammals.
- Walter CAnon developed the concept of homeostasis.
- He showed that there is an organized system that keeps the internal environment resistant to change.
- Bernard called homeostasis balance in the body; Canon called it ready ability to compensate.
[edit] Slide
- We are open systems; we can get rid of things through the GI tract to keep out ECF correctly balanced.
[edit] Slide
- Equilibrim: opposing forces are balanced; no net transfer between compartments; movement is equal and opposite; doesn't require energy to be maintained.
- Steady state: requires energy, nothing is changing,
- Example: distribution of Na (low in cells, high in ECF), balanced by active pumping out of the cell.
[edit] Composition of body fluids
- Interstitial fluid is same as plasma but without proteins.
[edit] Slide
- The differences between each fluid is imnportant.
- For example, the Na gradient is used to drive energy-requiring processes.
- distracted
[edit] Slide
- Understand mili-equivalents.
[edit] Feedback systems
- Have a sensor, effector, and regulated variable.
- Example: baroreceptors in vessels detect low bp, tell the heart to increase rate/force of contraction. Then a normal BP stops the signaling to increase rate / force.
- Neg feedback systems work to restore normal values.
- Feed forward control systems don't directly sense what is being regulated
- Example: blood glucose
- Incretins are released by GI when food enters, they act on the beta cells of the pancrease to get it ready to release insulin.
- Example: blood glucose
- Positive feedback systems:
- Make everything worse, quickly.
- Destabilizersrs
[edit] Water homeostasis
- 2/3 of our water is intracellular and 1/3 is extra cellular (for both males and females).
- Males have 60% water by weight, females 50% because of more fat stores.
- As water is lost, osmolarity increases.
- this causes an osmotic diff between intra and extra cellular such that water leaves the cells and cells shrink.
[edit] How do we fix this loss of water?
- Dehydration will cause increased plasma osmolarity which is detected by osmoreceptors which cause the release of ADH which causes water retention at the kidneys
[edit] Calcium homeostasis
- Distracted
- Relisten at 40'.
[edit] Potassium homeostasis
- Adrenal cortex detects increased potassium in plasma, releases aldosterone, kidney releases potassium.
[edit] Cortisol
- Some feedback loops are complicated.
- Cortisol is released in response to stress.
- Cortisol increases carbohydrate digestion and storage.
- Cortisol feedbacks on both the hypothalamus and the anterior pituitary.
- stopped here on 01/03/11.