WEEK 5: HOMEOSTASIS Flashcards
What is Human Physiology?
The study of the normal FUNCTION of the human body and the Integrative Mechanisms that control them.
Outline the levels of Structural Organization of the Human Body.
0- Chemical
1- Cellular
2- Tissue
3- Organ
4- System
5- Organism
State the principle of complementarity of structure and function.
All specific functions are performed by specific structures; in other words, what a structure can do depends on its specific form.
Describe how the body functions from cellular to systems.
1.Our bodies are made up of cells
2.The cells make up tissues (a group of cells with similar structure and specialized function): e.g. muscle tissue, nervous tissue, epithelial tissue or connective tissue
3.Our body organs (e.g. heart, lungs, liver, stomach, kidneys, or brain) are made up of two or more types of primary tissues that function together to perform a particular function(s)
3.Body systems (e.g. the cardiovascular system, the respiratory system or the gastrointestinal system) have been defined: these are made up of groups of organs that perform related functions and work together to achieve a common goal(s)
4.Normally, our body systems work in harmony as a highly sophisticated integrated unit to maintain a healthy body
State the necessary life functions.(7)
1.Maintaining boundaries- use of the cell membrane
2.Movement- involves propulsion eg. walking and running or internal displacement of things such as foodstuff, water, urine, etc
3.Responsiveness or Irritability – the ability to sense changes (stimuli) in the environment and then respond to them.
4.Digestion- the breakdown of ingested foodstuffs to simple molecules that can be absorbed into the blood.
5.Metabolism- all chemical reactions that occur in the body cells. Includes breakdown of substances into their simpler forms (catabolism) or synthesis of more complex structures from simpler substances (anabolism)
6.Excretion- the process of removing wastes (or excreta) from the body.
Reproduction- production of offspring; could occur at cellular or organism level
7.Growth – an increase in size of a body part or the organism; achieved by increasing the no. of cells
State the Five (5) Major Survival Needs.
1.Nutrients (food)- taken via diet, contain chemical substances required for energy and cell building.
2.Oxygen- human cells can survive for only a few minutes without oxygen. Most chemical reactions that release energy from foods require oxygen. 20% of the air we breathe is oxygen.
3.Water- accounts for 60-80% body weight; is the most abundant substance in the body. Obtained via ingested foods or liquids. Lost mainly through urine, faeces, lungs & skin.
4.Appropriate body temperature- all chemical reactions that occur in the body cells require an optimum body temperature.
5.Appropriate atmospheric pressure - the force that air exerts on the surface of the body. Influences breathing and gas exchange.
What is homeostasis?
“the maintenance of steady states within our bodies by coordinated physiological mechanisms”
Several components of our bodies internal environment must be maintained within narrow ranges.
State examples of them.
Concentration of water and electrolytes within and outside the cells
Pressures and volumes
Body Temperature
Concentration of nutrients e.g. glucose
Concentration of O2 and CO2
Concentration of waste products e.g. urea
State the 3 main characteristics that the control system must have in order to maintain homeostasis.
1.Sense deviations from normal in the internal environment that need to be held within narrow limits
(Sensor = 1)
Integrate this information with other relevant information (Control or integrating centre = 2)
Make appropriate adjustments in order to restore a controlled variable to its desired value (effector = 3)
Control systems are grouped into two classes.
State and describe them.
1.Intrinsic controls
Local controls that are inherent in an organ.
2.Extrinsic controls
-Regulatory mechanisms initiated outside an organ.
-Accomplished by nervous and endocrine systems
What is the difference between feedback and feedforward?
1.Feedforward
Term used for responses made in anticipation of a change.
-Feedforward usually act in combination with negative feedback - example is physical exercise
2.Feedback
Refers to responses made after change has been detected
State the 2 types of feedback systems.
1.Negative Feedback Systems - main type of homeostatic control
2.Positive Feedback Systems
Describe negative feedback.
State an example of negative feedback.
State the 3 components that make up the negative feedback.
1.Primary type of homeostatic control system.
Opposes initial change
2.Example: Control of blood pressure
3.Components are:
-Sensor
Monitors magnitude of a controlled variable
-Control center
Compares sensor’s input with a set point
-Effector(s)
Makes a response to produce a desired effect
Describe positive feedback and state examples.
1.Do not occur as often as negative feedback
-Amplifies an initial change
Examples: uterine contractions during labor become increasingly stronger until the birth of baby, the generation of an action potential
State the effect of disruption of homeostasis.
*Disruption in Homeostasis may Result in Disease or Death.
Many diseases are caused by deficient, inappropriate, or excessive homeostatic mechanisms.
Application of physiological knowledge is essential for the understanding of patient conditions, and may provide a rational for patient investigations, treatment, and health promotion
