Introduction to Physiology
Introduction to Physiology
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NECESSARY LIFE FUNCTIONS
NECESSARY LIFE FUNCTIONS
MAINTAINING BOUNDARIES:
MAINTAINING BOUNDARIES:
Maintain its boundaries so that its “inside” remains distinct from its “outside”.
Every cell of the human body is surrounded by an external membrane.
SYSTEM INVOLVED:
Integumentary system: protects internal organs from drying out bacteria, and from the damage brought by the external environment (e.g. heat, chemicals, etc. )
MOVEMENT
MOVEMENT
Includes all the activities promoted by the muscular system.
Also occurs when substances (e.g. blood, food, and urine ) are propelled through internal organs.
SYSTEM INVOLVED:
Muscular system
Skeletal system
Cardiovascular system ( blood ),
Digestive system ( food ) and
Urinary system ( urine )
RESPONSIVENESS
RESPONSIVENESS
A.K.A. Irritability
Ability to sense changes ( stimuli ) in the environment and then react to them.
SYSTEM INVOLVED:
Nervous system ( major responsibility )
DIGESTION
DIGESTION
Process of breaking down ingested food into simple molecules that then are absorbed into the blood.
SYSTEMS INVOLVED:
Digestive System
METABOLISM
METABOLISM
A broad term that refers to all chemical reactions that occur within the body and all of its cells,
SYSTEMS INVOLVED:
Digestive System ( to make nutrients and oxygen )
Respiratory System ( to make nutrients and oxygen )
Cardiovascular System ( for distribution )
EXCRETION
EXCRETION
Is the process of removing excreta, or wastes from the body.
SYSTEM INVOLVED:
Digestive system
Urinary system
REPRODUCTION
REPRODUCTION
The production of offspring
Can occur on the cellular or organismal level
SYSTEMS INVOLVED:
Reproductive system
Endocrine System ( hormones regulate the function of the reproductive system )
GROWTH
GROWTH
Can be an increase in cell size or an increase in body size that is usually accomplished by an increase in the number of cells.
SYSTEMS INVOLVED:
Endocrine system
© By Pearsons College Div.
SURVIVAL NEEDS
SURVIVAL NEEDS
NUTRIENTS
Which the body takes in through food.
Contains the chemical used for energy and cell building.
Some nutrients:
Carbohydrates: are major energy-providing fuel for body cells.
Proteins: essential for building cell structures
Fats: to a lesser extent. Is essential for building cell structures. Also cushions organs and provides reserved fuel.
Minerals & Vitamins: required for the chemical reactions that go on in cells and for oxygen transport in the blood.
OXYGEN
Is required during chemical reactions that release energy from foods.
Human cells survive for only a few minutes without it.
WATER
60 to 80 percent of body weight
Single most abundant chemical substance in the body
Provides the fluid base for body secretions and excretions.
We obtain water from ingested foods or liquids, and we lose it by evaporation from the lungs, skin, and in body secretions.
NORMAL BODY TEMPERATURE
If chemical reactions are to continue at life-sustaining levels, normal body temperature should be maintained.
As body temperature drops below 37℃, metabolic reactions become slower and slower and finally stop.
ATMOSPHERIC PRESSURE
The force exerted on the surface of the body by the weight of air.
Breathing and the exchange of oxygen and carbon dioxide in the lungs depend on appropriate, atmospheric pressure.
High altitude = air is thin = atmospheric pressure is lower, which means that the gas exchange is too slow to support cellular metabolism.
HOMEOSTASIS
HOMEOSTASIS
Body’s ability to maintain relatively stable internal conditions even though the outside world is continuously changing.
A dynamic state of equilibrium, or a balance in which internal conditions change and vary but always within relatively narrow limits.
Is demonstrated when its needs are being adequately met and it is functioning smoothly.
Communication within the body is essential for homeostasis and is accomplished chiefly by the nervous and endocrine systems, which use electrical signals delivered by nerves or blood-borne hormones, respectively as information carriers.
It is important that most diseases can be regarded as being the result of their disturbance, called homeostatic imbalance.
© By Pearson College Div.
COMPONENTS OF HOMEOSTATIC CONTROL
COMPONENTS OF HOMEOSTATIC CONTROL
RECEPTOR
RECEPTOR
A type of sensor that monitors and responds to changes in the environment.
It responds to such changes, called stimuli, by sending information (input) to the second component, the control center.
Information flows from the receptor to the control center along the afferent pathway.
CONTROL CENTER
CONTROL CENTER
Determines the set point at which a variable is to be maintained.
Analyzes the information it receives and then determines the appropriate response or course of action.
EFFECTOR
EFFECTOR
Provides the means for the control center’s response (out-put) to the stimulus.
Information flows from the control center to the effector along the efferent pathway.
The results of the response then feedback to influence the stimulus ( the original change) which could either be:
- NEGATIVE FEEDBACK:
Most homeostatic control mechanisms are negative feedback.
Reducing the amount of change, so that the whole control mechanism is shut off
Examples:
Regulates heart rate,
Blood pressure,
Breathing rate,
The release of hormones,and
Blood levels of glucose (blood sugar), oxygen, carbon dioxide, and minerals.
- POSITIVE FEEDBACK:
This mechanism is rare in the body because they push the variable farther away from its original value or set point.
Increasing the amount of change, so that the reaction continues at an even faster rate.
Examples:
Blood clotting
Giving birth
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