What does it mean to be living? maintain boundaries, movement, responsiveness, digestion, metabolism, excretion, reproduction, growth

1) Maintain boundaries The "inside" must be distinct from the "outside" Cellular level: membranes holds in the organelles lets in necessary substances prevents entry to damaging or unnecessary substances Organismal level: skin (integumentary system) holds in our organs and lines all of our organs protects internal organs from drying out, bacteria, damaging effects of heat/sunlight/chemicals

2) Movement locomotion movement of substances blood: cardiovascular food: digestive urine: urinary Cellular level: movement of substances such as blood/foodstuffs/urine through internal organs Organismal level: movement promoted by muscular system works hand-in-hand with skeletal system

3) Responsiveness the ability to sense changes in the environment and then react to them Cellular level: nerve cells are very responsive and can communicate and send off impulsive all body cells are responsive to some extent Organismal level: your own reflexes! burning your hand on a stove elicits a response from the muscular system buildup of CO2 in the blood elicits a response from the respiratory system

4) Digestion the process of breaking down ingested food into simple molecules that can be absorbed Cellular level: intracellular digestion: occurs within the cell single-celled organisms like amoeba and protozoans extracellular digestion: occurs outside the cell through the secretion of enzymes worms, insects, crustaceans Organismal level: digestive system mouth, stomach, small/large intestine

5) Metabolism a broad term that refers to all chemical reactions that occur within body cells production of energy making body structures Cellular level: breaking down complex substances into smaller building blocks and using oxygen/nutrients to make ATP Organismal level: Digestive and respiratory system make nutrients and oxygen available to blood Cardiovascular system distribute substances throughout the body Endocrine system regulates metabolism

6) Excretion Excretion: the process of removing wastes from the body Cellular level: exocytosis removes cellular wastes Organ level: Digestive system rids body of food residues through feces (poop) Urinary system disposes of nitrogen-containing metabolic wastes in urine (pee)

7) Reproduction production of offspring Cellular level: original cell divides to produce two identical daughter cells Sound familiar? Mitosis! Organismal level: Reproductive system components (egg and sperm) unite to eventually form a baby Endocrine system regulates the hormones associated with the reproductive system

8) Growth increase in size, usually accomplished by an increase in the number of cells For this life function, only the cellular level exists

What do you need to survive? Kumbaya definition

What do you need to survive? Textbook definition Nutrients chemicals for energy and cell building includes carbohydrates, proteins, lipids, vitamins, minerals Oxygen required for chemical reactions cellular respiration, anybody?

What do you need to survive? Water 60-80% of body weight provides for metabolic reactions Stable body temperature Appropriate atmospheric pressure

How does the body regulate what we need? Homeostasis: the body’s ability to maintain relatively stable internal conditions even though the outside world is constantly changing a dynamic state state of equilibrium connect “dynamic” to lit term (dynamic character is one that changes over the course of the story)

Homeostasis regulates temperature, water balance, pH balance, ion/mineral balance, organic compound balance, gaseous content balance

How are these conditions controlled? Feedback mechanisms a control mechanism which monitors a specific quantity, then is able to make a change so that the quantity is changed

Negative feedback The net effect of the response to the stimulus is to shut off the original stimulus or reduce its intensity Our bodies work the same way our “thermostat” is the our hypothalamus Other negative feedback mechanisms regulate heart rate, blood pressure, breathing rate, and blood levels of glucose/oxygen/carbon dioxide/minerals

Positive Feedback increases the original disturbance and pushes the variable farther from its original value blood clotting and birth of a baby contractions keep getting more and more intense and hormones kept at abnormal levels until the baby is born