Lecture 1 Flashcards
Themes of Physiology
Physical-chemical basis of body function structure function relationships energy use homeostasis integration
Physical-chemical Basis of body function
focus on MECHANISM: how the body works
Structure-function relationships
Body function depends on structure at all levels of biological organization
Cell basic unit of life
organism is the most highly integrated level
Energy Use
life requires a continuous input of chemical energy
body cells obtain energy
Homeostasis
maintenance of relatively constant internal conditions in the body
central principle of physiology
Integration
Body systems are functionally connected and work together
Integration of organ systems
what do they do and what controls them, role of circulatory system
OS work together to support body function
OS share a common internal environment; some organ systems have surfaces that contact the external environment
Nervous system and endocrine system control other organ systems
circulatory system transports and exchanges substances w/ other organ systems
External environment
Includes lumen of hollow organs that open to outside
Part of external environment
respiratory, digestive, urinary, reproductive
Extracellular fluid (ECF)
Internal environment
contains interstitial fluid (11L) and blood plasma(3L)
1/3 of total body water
major solutes: Na+, Cl-, some organic molecules
Functions as buffer between cells and external environment
ECF Is high in _ and low in _
high in Na+
Low in K+
Intracellular fluid (ICF)
2/3 of total body water
major solutes K+ and organic molecules A-
contained in trillion of cells
Intracellular fluid is high in _ and low in _
low Na+
high K+
Plasma Membrane
separates ICF and ECF
maintains different composition of ICF and ECF by selective permeability and molecular transport
prevents easy movement of ions
Epithelium
Forms boundary between internal environment (ECF) and external environment
A protective barrier
exchanges surfaces
functions in absorption, secretion, gas exchange
Free Surface
faces external environment (or lumen of hallow organs)
Law of Mass balance (steady state process)
open system, INPUT=OUTPUT to maintain a constant level
Example: input (food+drink+metabolism) = output (urine+feces+evaporation)
What is required to maintain homeostasis
ENERGY
ex. Na-k pump uses ATP to maintain [Na+] and [K+] of ICF and ECF
ex. cellular respiration
Why is the ECF regulated
to maintain suitable conditions for cells
7 essential variables
body temp, arterial blood pressure, pH, Po2, Pco2, blood, plasma osmolarity
Body Temperature
37*C
Arterial Blood Pressure
120/75 mm Hg
Mean = 90 mm Hg (millimeters of mercury)
Arterial pH
7.4, slightly alkaline
Arterial Po2
P= pressure
pressure of o2
100 mm Hg
Arterial Pco2
carbon dioxide pressure
40 mm Hg
Blood [glucose]
when fasting
90 mg/dL
Plasma osmolarity
290 mOsm (concentration of all dissolved substances in plasma)
Control of homeostasis
Negative feedback control maintains homeostasis
usually regulated by nervous and endocrine systems
set point
optimum value/normal value
variable are regulated around a set point
Direction of response
corrective response is in the opposite direction during negative feedback
ex: heat gain means heat loss to decrease body temp
heat loss means heat gain to increase body temp
If you are too Hot what happens
the skin are hypothalamus detect that you are too hot (sensors)
sweat glands release sweat and vasodialation occurs
(effectors)
body temperature decrease (response)
Positive feedback
non-homeostatic
results in rapid change of variable
Not very common
Ex. LH surge triggers ovulation
