pt 2 key concepts: bodily functions, survival needs and homeostasis

metabolism

necessary functions: chemical rxns within the body

• break down complex molecules into smaller ones

• build larger molecules from smaller ones

• produces energy

• regulated by hormones

excretion

• eliminates waste from metabolic rxns

• wastes may be removed in urine or feces

reproduction

• occurs on cell or organism level

• future gen

growth

• increases cell size and number

nutrients, O2, h2o, body temp, atm pressure

survival needs

nutrients

chemicals for energy and cell building

carbs, proteins, lipids, vits, minerals

o2

reqd for efficient ATP production

h2o

• 60-80% of body weight

• most abundant chemical in body

• metabolic rxns

stable body temp

37 celsius/98.6 fahrenheit

atm pressure

must be appropriate for gas exchange

homeostasis

maintenance of a stable internal env

• dynamic equilibrium

homeostatic control system

• stimulus

• receptor

• input → control center

• control center → output

• response

receptor

detect and respond to change in environment (stimuli)

send info to control center along and afferent pathway

control center

determines set point

analyzes info

determines appropriate response

effector

info flows from control center to effector along efferent pathway

provides means for response to stimulus

negative feedback

most common feedback loop

• response nullifies/reduces intensity of stimulus

• moves variable back towards setpoint

positive feedback

less common feedback loop

• increases original stimulus to push variable farther from setpoint

• rxn occurs at a faster rate

• occurs in hemostasis, labor, production'

• stimulus from outside the feedback loop is required to shut down this loop