Homeostasis Flashcards
Physiology
Physio: natural causes and phenomena
Ology: the study of
Body- function
- explains “why” something happens
- Teleological approach
Body- process or mechanism
- describes the “how” something happens
- mechanistic approach
Metabolism
sum of all chemical reaction in the body
responsiveness
react and change to environment
movement
- change in pace, posture, position or place
- internal: movement of substances within the body
- External: move either pats or entire body from place to place
Growth
increase in the number and size of cells In an organism
Differentiation
less specialized cell matures to a more distinct form and function
reproduction
production of offspring by organized bodies
Cells
basic structural and functional units of an organism
Tissues
consist of groups of similarly specialized cells and the substances surrounding them that usually arise from a common ancestor and perform certain special functions
Organs
are structures of definite form that are composed of two or more different tissues and have specific functions
Systems
consist of related organs that have a common function.
Human organism
is a collection of structurally and functionally integrated systems; any living individual
Homeostasis
- Is a condition of equilibrium, or balance, in the body’s internal environment
- maintained by the body regulatory processes
To maintain homeostasis, control system must:
– detect deviations from normal in the internal environment that need to be held within narrow limits
– integrate this information with other relevant information
– make appropriate adjustments to restore a factor to its desired value
Set point
normal range for a given system , will be monitored by the control centre for that particular system
Circadian Rhythm
Circadian rhythms are endogenous autonomous oscillators of physiological activities that result in an ~24 hour day/night cycles, which allow organisms to adapt to a fluctuating environment
* The circadian clock system is a major regulatory factor for nearly all physiological activities and its disorder can have severe consequences on human health.
Intrinsic controls
local controls that are inherent in an organ
Extrinsic controls
- regulatory mechanisms initiated outside an organ
- accomplished by nervous and endocrine systems
Dynamic equilibrium adjustments
Feedback loops: responses made after a change, negative or positive
Feedforward loops: responses made in anticipation of a change
The basic components of a feedback loop
stimulus-> controlled condition-> receptors-> control center-> effectors-> response that alters the controlled condition-> -> return to homeostasis, brings controlled condition back to normal
Negative feedback loop
- opposes initial change
- components:
Sensor: monitors magnitude of a controlled variable
Control centre: campares sensor’s input with a setpoint
effector: Makes a response to produce a desired effect
Negative feedback main goal
- keeping internal environment stable
- only control within the body, not what is in the outside world
Ex: temperature, nutrients/waste, O2/CO2 levels, ph, water/eletrolytes, blood volume and pressure
Positive feedback loop
- Amplifies an initial change and therefore does not truly contribute to homeostasis
- Does not occur as often as negative feedback systems
– Abnormal changes move the body farther away from homeostatic balance and, potentially, toward death.
Positive feedback main goal
- Response reinforces the stimulus
- snowball effect (gets bigger and bigger and bigger - rolling a snowball down a hill)
Ex: Contractions during labour
Homeostatic imbalances
Disruption of homeostasis can lead to disease and death
Disorder
is a general term for any derangement of abnormality of function
Disease
is a more specific term for an illness characterized by a recognizable set of signs and symptoms
Aging and homeostasis
aging is a normal process characterized by a progressive decline in the body’s ability to restore homeostasis
Feedforwrd mechanisms and anticipation
Although not as common in the body as negative feedback loops, there are mechanisms which are activated before a change in a variable actually occurs.
- These mechanisms attempt to anticipate changes before they occur, rather than responding to a change after it has occurred.
Ex: digestion: saliva production prior to eating, food in digestive tract (increase secretion of insulin to promote cellular uptake and storage of nutrients)
Feedforward central command
Primes the body for the changes that are about to take place during the exertion
– Oxygen demand increases to working muscles
– Cardiac output increases up to 6-7x
– Oxygen extraction rates can increase 2-3x
