ch 1 intro to physiology Flashcards
physiology
- form dictates function
- how a molecule is shaped determines the job that it does
levels of physiology organization
- molecules (ATP, water, neurotransmitter receptor)
- cells (neurons, epithelial cells)
- tissue (nervous tissue, muscle tissue)
- organs (heart liver)
- organ systems (cardiovascular, gastrointestinal)
four major cell/tissue types: neurons
- neurons/nervous tissue (motor neurons, cortical interneurons, etc)
- specialized for sending and receiving information
- purpose: communication
- the body is controlled by mainly the nervous and the endocrine system
four major/tissue types: muscle
- muscle (cardiac myocytes, skeletal, smooth)
- specialized for contraction
- generate movement of some kind
- skeletal is attached to bone (voluntary)
- cardiac is the heart (involuntary)
- smooth is internal organs (involuntary)
four major tissue types: epithelial
- epithelial tissue (intestinal, epithelial, etc)
- found on organs, glands, and lining body cavities
- used for exchange and makes up boundary between one area and another.
- lines all of your body orifices like mouth, nose, ears, skin and glands
endocrine
- secrete molecules (usually hormones) directly into the blood stream. i.e. pancreatic and thymus glands
- *both secrete something difference is where (endocrine: blood stream)
exocrine
- utilize a duct (small passageway to either outside of body or into body cavity)
- secrete molecules into a body cavity
- to the exterior of the body
- stomach, salivary, sweat glands
- does not enter the bloodstream
(exocrine: into body cavity or outside)
the four major cell/tissue types: connective tissue
- includes bone cells, bld cells, fat cells, cartilage, tendons, ligaments
- ligament: bone to bone
tendon: bone to muscle (achillies) - characterized by very few cells and lots of extracellular material (water, protein, salts)
homeostasis
- ability to maintain a relatively stable (small change is ok) internal environment despite fluctuations in the external environment
- essential for survival and function of all cells
- deviation from homeostasis indicates disease (fever)
how is homeostasis accomplished?
negative feedback
homeostasis example
stable not steady
- internal conditions dont change drastically
- temp is not always 98.6
- if the temp outside is 105, your body temp will prob go up to 99
- if the temp outside is 30’s your body temp will prob go down to 98
negative feedback
- returning internal conditions to a “set point”
- neg feedback loop helps return internal conditions to a set point when they deviate too far outside of an acceptable rang
- input and output are opposites
negative feedback example
- sweat when you get hot. the sweat evaporates and cools you off.
- input: hot
- output: cool
- ex: shivering when you get cold
- sensor: found on skin that let body know your temp is too hot
- integrating center: usually brain
- effector: sweat glands
negative feedback involves:
- sensors: detect change and send info to integrating center
- integrating center: assesses change around set point. then sends instructions to an effector
- effector: makes the appropriate adjustments
why do people often shiver when they have a fever?
- changing the body temp set point (hypothalamus)
- elevated set point causes heat retaining/producing physiological responses such as vasoconstriction and shivering (shivering helps make fever happen)
- fever makes you feel cold because the temp set point changed
why do people often shiver when they have fever pt 2
- helps fight infection by activating immune cells bc pathogen survived with 98.6
- hypothalamus causes fever to destroy it
- hypothalamus says what the set point is which is why you dont feel hot or cold at set point 98.6
- fever: new set point is 103 (to kill pathogens) if 103 is the new ‘normal’ and you are at 98.6 you will feel cold and shiver to produce body heat
- once infection is destroyed the hypothalamus changed set point back to 98.6 from 103, now you feel hot. sweating to cool back down to 98.6
- sweat = broke fever, soon will feel better :)
antagonistic effectors
working towards same goal
- homeostasis is often maintained by opposing effectors that move conditions in opposite directions
- this maintains conditions within a certain normal range or dynamic (change) constancy
- when you are hot you sweat, when you are cold you shiver, these are antagonistic reactions (to keep temp constant)
antagonistic effectors example
- do the exact opposite of each other but working towards same goal/ keep conditions stable
- insulin is a hormone that lowers bld sugar. glucagon is a hormone that raises your bld sugar
- insulin and glucagon are antagonistic effectors
antagonistic effectors explanation
- effectors dont exist to keep conditions from never changing, they exist to keep them from changing drastically
- 97 temp or 99 is not unhealthy
- 94 temp or 106 is unhealthy
positive feedback
- input and output are the same
- moves conditions further away from set point
- ex: uterine contractions during child during child birth
- release of oxytocin causes the uterus to contract. this pushes baby’s head against the cervix activating stretch receptors that signal the hypothalamus to release more oxytocin which results in stronger contractions
positive feedback example
- mosquito bite and it itches
- so you scratch it and cause histamine to be released which causes to itch some more.
- input itching and output is itching
