Introduction to Physiology Lecture Sep 16 Flashcards
What is physiology?
the study of how the various parts of the body work together to achieve optimal functional capacity of the body.
What were Cannon’s 4 propositions to describe homeostasis?
- constancy in an open system, such as our bodies represent require mechanisms that act to maintain this constancy
- Steady state conditions require that any tendency toward change automatically meets with factors that resist change
- the regulating systems that determine the homeostatic state consist of a number of cooperating mechanisms acting simultaneously or succinessivly
- homeostasis does not occur by change, but is the result of organized self-government
What are the 9 organ systems with their basic functions?
DR. CIRUMIN
Digestive: break down food and take in nutrients
Respiratory: exchange of gases
Circulatory: mass delivery system
Integumentary: skin, protection
Reproductive: proliferation of species
Urinary: control of water and salt concentration, excretion
Musculoskeletal: movement - reactive to environment
Immune: protection from invaders
Nervous/Endocrine: internal messaging
What is the difference between the teleological and mechanistic approaches to understanding physiological processes?
Which is better in terms of medical school?
The teleological understanding asks WHY the body does something.
The mechanistic approach asks HOW the body does something.
Describe a simple control system.
There is an input signal
A controller receives the input signal and compares it to the setpoint
An output signal gets set to modify bodily function or behavior
What are controlled variables?
Give examples.
A controlled variable is something that the body must maintain within a very narrow range in order to keep the cell happy.
Examples include blood glucose, arterial pressure, and body temperature
What is a steady state?
When there is no net change in the controlled variable.
There may still be movement back and forth, but every motion in one direction is balanced by motion in the other direction
What is a negative feedback system?
there is a primary disturbance in a variable and then a compensatory response to get the variable back to equilibrium
It acts to maintain the control variable at set value
This is a GOOD thing.
A change in a controlled variable evokes a compensatory response that NEGATES the first effector
What is a positive feedback system?
It acts to reinforce a change in a variable, accelerating the change and leading to an “explosion” and breakdown of the homeostatic system.
This is BAD.
WHat is the basic path of a reflex?
What is the difference between a neural and hormonal reflexes?
signal > sensory receptor > afferent neurons > integrating center > efferent neuron > effector organs
Neural reflexes use nerves, but the hormone system uses chemicals transported in the blood
What is the definition of the following:
endocrines
neurocrines
paracrines
autocrines
endocrine - hormones carried in the blood to distant target cells
neurocrine - NT released from nerves to act on a neighboring cell
paracrine - local chemical messengers that act on neuboring cells
autocrines - locally secreted chemical messengers that go back and act on the secreting cell
Describe the homeostasis mechanism for thirst.
- A perons is working outside on a hot, dry day
- they lose body water by evaporation
- body fluids become mroe concentrated
- internal receptors sense the change in internal concentration
- thirst pathways are stimulated
- person seeks out and drinks water
- water added to body fluids decreases their concentration
