BIO 323-Ch. 1 & 6: An Introduction to Physiology & Homeostatic Control Mechanisms

Anatomy

study of structure; "to cut apart"

Subdivisions of Anatomy

gross or macroscopic & microscopic

Physiology

study of function

physis

nature

Hippocrates

Father of Medicine

Hippocrates' definition of "physiology"

the healing power of nature

levels of organization

atoms, molecules, organelles, cells, tissues, organs, organ systems, organisms, populations of one species, ecosystem of different species, biosphere

chemistry levels of organization

atoms and molecules

molecular biology levels of organization

molecules and cells

cell biology levels of organization

molecules, cells, and tissues

physiology levels of organization

molecules -> populations of one species

ecology levels of organization

organisms -> biosphere

necessary life functions

maintaining boundaries, movement, responsiveness, digestion, metabolism, excretion, reproduction, growth

teleological approach

thinking about a physiological event in terms of its adaptive significance; "Why?"

mechanistic approach

thinking about a physiological event in terms of the process; "How?"

biological themes in physiology

1. complementarity of structure & function across all levels of organization

2. energy transfer, storage, & use

3. information flow, storage, & use within a single organism and within a species

4. homeostasis and the control systems that maintain it

5. evolution as the organizing principle

Why do the lungs have many small sacs?

to increase surface area

What is the function of the pinna?

to capture sound

What does the structure of a protein determine?

its function

Where is glycogen stored?

liver and muscles

Central Dogma

DNA -> RNA -> Protein

types of cellular communication

local, long distance, & from outside to inside the cell

Homeostasis

process by which organisms maintain a relatively stable internal environment

How did Claude Bernard describe homeostasis?

"It is the constancy of the internal environment that is the condition for a free & independent life."

Who coined "homeostasis?"

Walter Cannon

variables under homeostatic control

osmolarity, temperature, pH, ion balances

conformers

organisms that change their internal conditions with the external environment

mass balance

input = output

local control

cells in the vicinity of the change initiate the response

negative feedback

a mechanism of response in which a stimulus initiates reactions that reduce the stimulus

antagonistic control

uses different signals to send a parameter in opposite directions

tonic control

ongoing control that is adjusted up and down

Is sodium concentration higher inside or outside of the cell?

outside

Is potassium concentration higher inside or outside of the cell?

inside

Is chloride concentration higher inside or outside the cell?

outside

reflex pathway

stimulus, sensor, input signal, integrating center, output signal, effector, response

Pathophysiology

the study of body functions in a diseased state

reflex control

cells at a distant site control the response

example of positive feedback

labor contractions, blood clotting

example of negative feedback

body temperature regulation

example of antagonistic control

regulation of heart rate

example of tonic control

vasodilation/vasoconstriction

emergent properties

properties that cannot be predicted to exist based only on knowledge of the system's individual components

examples of human emergent properties

emotion, intelligence, other aspects of brain function

cell

the smallest unit that can perform all life processes

tissues

groups of similar cells that perform a specific function in an organism

organs

groups of tissues that work together to perform a specific function or related functions

organ systems

a group of two or more organs working together for a specific job

integumentary system

forms a protective boundary that separates the body's internal environment from the external environment

musculoskeletal system

provides support and body movement

respiratory/pulmonary system

exchange of oxygen and carbon dioxide between the internal and external environments

digestive/gastrointestinal system

conversion of food into particles that can be transported into the body; elimination of some wastes

urinary/renal system

maintenance of water and solutes in the internal environment; waste removal

reproductive system

produces eggs or sperm

circulatory/cardiovascular system

distributes materials by pumping blood through vessels

nervous system

coordination of body function through electrical signals and release of regulatory molecules

immune system

defense against foreign invaders

endocrine system

coordination of body function through synthesis and release of regulatory molecules

function

adaptive significance; "Why?"

mechanism

"How?"

translational research

research that uses insights and results gained from basic biomedical research on mechanisms to develop treatments and strategies for preventing human diseases

example of translational research

amylin reduces rats' food intake; amylin now used to treat diabetes mellitus

What determines a molecule's function?

shape and structure

example of structure-function relationship

a change in a single amino acid of hemoglobin converts normal hemoglobin to the form associated with sickle cell disease

compliance

ability to stretch

elastance

ability to return to the unstretched state

compartmentation

division of space into separate compartments

What happens when the body fails to maintain homeostasis?

pathological condition

pathological

diseased

diabetes mellitus

a metabolic disorder characterized by abnormally high blood glucose concentrations

extracellular fluid

watery internal environment that surrounds the cells

intracellular fluid

watery fluid inside the cell

load

amount of a substance in the body

excretion

elimination of material from the body

xenobiotic

any foreign substance in the body

mass flow

aids scientists in following material through the body

mass flow equation

= concentration of x (amount x/vol) * volume flow (vol/min)

clearance

the rate at which the substance disappears from the blood

hepatocytes

liver cells

plasma

liquid portion of blood

setpoint

optimum value

response loop

input signal, integrating center, output signal

feedforward control

control that allows the body to predict that a change is about to occur

circadian rhythm

a daily biological rhythm

acclimatization

physiological adjustment to a change in an environmental factor; occurs naturally

acclimation

physiological adjustment to a change in an environmental factor; occurs in a lab setting

parameter

regulated variable

Cannon's postulates

1. The nervous system has a role in preserving the "fitness" of the internal environment

2. Some systems of the body are under tonic control

3. Some systems of the body are under antagonistic control

4. One chemical signal can have different effects in different tissues

threshold

minimum stimulus needed to set the reflex response in motion

stimulus

disturbance or change that sets the pathway in motion