Intro Physiology And Homeostasis Flashcards
What is the definition of Physiology
The study of the normal functioning of a living organism and its component parts
Physiology is an integrative science and closely tied to:
Anatomy; the structure of a cell, tissue, or organ must provide a physical basis
Smallest unit of structure capable of carrying out life processes?
Cells
Collection of cells carrying out related functions?
Tissue
Formation of tissues into a structural and functional unit?
Organ
Integrated groups of organs?
Organ System
What are properties of a complex system that cannot be explained by a knowledge of a systems individual components?
Emergent Properties
What do emergent properties result from?
Complex, nonlinear interactions of the systems different components
Which physiologists take a teleological approach
Function or “why”
Which physiologists take a mechanistic approach?
the mechanism or “how”
What is Homeostasis
The ability to maintain a relatively stable internal environment despite exposure to external variability
What are humans normal internal body temperature?
Around 37 degrees Celsius
Homeo=
Homo=
Stasis=
Like or similar (range of values)
Same
Condition (not a static state)
Examples of External change in Homeostasis
Exposure to;
Toxic chemicals
Physical trauma
Foreign invaders
-these all throw off homeostasis
Examples of Internal change in homeostasis
Inside the body;
Abnormal cell growth
Autoimmune disorders
Genetic disorders
-caused by abnormal functioning proteins
Are cells tolerant or not to changes in their surroundings?
Not tolerant, they are fragile and this is why we need homeostasis
What is Extracellular Fluid
A fluid that surrounds cells, is a buffer between cells and the external environment
What law is: if the amount of a substance in the body is to remain constant, any gain must be offset by an equal loss?
Law of Mass Balance
-input needs to match output, vice versa
Differences between ECF and ICF
ECF is relatively easily to monitor (plasma), while ICF is hard
How does the body maintain homeostasis
It monitors certain key functions/ variables by controlling bisystems that kick in when values deviate
Control System Steps:
Input signal, Integrating centre, Output signal, Response
What is Local Control
-restricted to tissues or cells involved
Active cells create reduced O2 levels in tissue
-too much oxygen= lower levels
-input signal causes decrease in oxygen
For anything variable in the body that remains constant, when there is an increase in this variable there must be an equal removal: this is best defined as;
Mass Balance
What is Reflex Control
-uses long distance signalling
-uses more complex control systems to maintain homeostasis -e.g. blood pressure
-any long distance pathway that uses the nervous, endocrine system, or both
Negative/ Positive feedback, Feedforward control
Facts of Negative Feedback Loops
-a pathway in which the response opposes or removes the stimulus signal
-can’t prevent, but reacts
-stabilizes a system, is homeostatic
Baroreceptor reflex: Reflex Control system example
Stimulus: stretch of artery wall due to increased pressure
Sensor: baroreceptor
Input signal: mechanical stretch
Integrating centre: medulla
Output signal: signals sent toward target tissues
Target: heart and peripheral arterioles
Response: reduced HR, SV, peripheral dialation
info on Positive Feedback Loops
-NOT homeostatic
-reinforce stimulus to drive system AWAY from normal value
-needs intervention or event outside of loop to stop response
Ex) uterine contractions
Feedforward Control
-a few reflexes have evolved that allow the body to predict a change is about to occur
-body anticipates change and prepares for it
Ex) horse starts breathing heavy before a race
