Lecture 1 Terms/Questions/Outline Flashcards
What is physiology?
comes from the Greek word PHUSIOLOGIA
- means knowledge of nature
Definition of physiology
is the study of the normal functioning of a LIVING ORGANISM and its component parts
Definition of “living”, or “alive” (minimum of 4 conditions)
- Made of one or more cells (cell is basic unit of life)
- Regulate its internal environment
- Respond to stimuli (“sensory systems” to detect stimuli)
- Capable of reproduction (self-replication)
Levels of organization of life sciences, where physiology fits in (Fig 1.1)
Chemistry - atoms - molecules Molecular Biology - cells Cell Biology - tissues Physiology - organs - organ systems - organisms (behaviour) - populations of one species Ecology - ecosystem of different species - biosphere (behaviour)
Why is physiology important?
- leads to treatment of diseases in humans & other organisms (pathophysiology)
- helps us understand how organisms cope with environmental stressors
- foundation of understanding of the philosophical question “What is life?”
- required credit for some academic programs, requirement for MCAT, PCAT…
What is homeostasis?/Definition
the ability to maintain a RELATIVELY constant internal environment even when the external environment is variable
- in the 1800’s Claude Bernard called this “la fixite du MILLIEU INTERIEUR”
- word was coined by Walter Canon, 1929
internal environmental parameters of an animal must be regulated to within certain levels to support life
- temp, pH, salinity (concentration of ions & other solutes), oxygen, carbon dioxide, nutrients
What is a control system?
monitors & adjusts regulated variables (internal temp, pH, salt balance, etc)
Internal vs external environments
homeostasis does NOT mean “equilibrium”
- we observe a dynamic steady state inside vs outside cells
homeostasis does NOT mean “never changing”
- internal parameters change often, in response to environmental challenges
A general scheme of homeostasis
- organisms in homeostasis (external change or internal change)
- internal change results in loss of homeostasis
- organism attempts to compensate (compensation fails or compensation succeeds)
- illness or disease or wellness
What is a control system?
- homeostasis requires control systems
- monitors & adjusts regulated variables (internal temp, pH, salt balance, etc)