Maintaining Life Necessary Life Functions

Factors that must be available to the organism to maintain life: Survival Needs Factors that must be available to the organism to maintain life: Nutrients: Carbohydrates, Proteins, Lipids, Nucleic Acids, minerals/vitamins Oxygen: Required for cellular respiration Water: Provides transport, secretions/excretions Body Temperature: maintained by metabolic processes and water Atmospheric Pressure: Breathing and Exchange of O2/CO2

Maintaining Boundaries Every organism must keep distinction between what is “inside” from what is “outside”. Cellular level: Cell Membrane(selectively permeable) Body as a whole: Integumentary System(skin) Control and regulate: temp, fluid balance, chemical substances, sunlight, pathogens, etc

Musculoskeletal System Movement Musculoskeletal System Substances All movements promoted by the muscular and skeletal systems. Movement of materials through the body via cardiovascular, excretory, digestive, lymphatic systems.

Responsiveness/Irritability The ability to sense changes(stimuli) in the environment and react to them.

Digestion Process of breaking down large macromolecules(C,P,L,NA) in food material to small simple molecules(monomers) so they can be absorbed and carried by the blood to all cells.

Excretion Process of removing waste, excreta, from the body produced during digestion and metabolism Digestive system removes indigestible food residues as fecal material Excretory system removes nitrogen-containing metabolic wastes as urine.

Reproduction The production of offspring, both at the cellular level(mitosis/cytokinesis) and of the organism(meiosis/fertilization) Endocrine system provides the hormones that regulate the reproductive systems.

Growth To increase in size through increasing the number of cells. For growth to occur, cell-constructing activities must occur faster than cell-destroying activities.

HOMEOSTASIS The body’s ability to maintain relatively stable internal conditions even though the outside environment is continuously changing. homeo=the same stasis= standing still Actually a dynamic state of equilibrium where internal conditions change and vary but balance is maintained as long as needs are being met and body is functioning smoothly. All organ systems function to maintain homeostasis.

Homeostatic Control Mechanisms Variable: Factor or event being controlled or regulated. Stimuli: change in the environment Receptor: Sensor that monitors and responds to stimuli by sending information(input) to control center Control Center: receives input from receptor along the afferent pathway, sets level of maintenance-analyzes input-sends appropriate response Effector: provides means for control centers response. The response travels to the effector via the efferent pathway where the feedback influences the stimulus by depressing it or enhancing it.

Negative Feedback Mechanisms Most homeostatic control mechanisms are negative, in that, the net effect of the response is to shut off or reduce the intensity of the original stimulus and return the body to its original state Examples: body regulatory mechanisms like temperature, blood pressure, heart rate, pH, blood levels of glucose, oxygen, carbon dioxide, etc

Positive Feedback Mechanisms These homeostatic responses are rare because they tend to increase the original disturbance(stimulus) and to push the variable farther than its original value. They control events that occur infrequently. Examples: Blood clotting, birth of baby