A+P: Homeostasis and Boundary Organs

4/4 lecture 1

anatomy

arrangement: focuses on structure of body parts and the relationships between them

physiology

function: focuses on the function of body parts and how they work to carry out life sustaining activities

structure-function relationship

function informs form, and vice versa; in all levels from molecules to organ systems

levels of organization

chemical, cellular, tissue, organs, organ system, organism

emergent properties

properties that arise from interactions of parts within the whole, but are not apparent solely in the individual. for example, cells alone cannot create tissue, but cells interacting together can create tissue. consider levels of organization; ie organs form organ systems, etc.

chemical level

atoms, molecules, hemoglobin protein and other macromolecules

cellular level

phospholipid molecule, phospholipid membrane, plasma membrane

tissue level

similar types of cells and associated extracellular material

organ level

discrete structures made up of multiple tissue types (ie smooth muscle tissue, epithelial tissue, connective tissue all form the blood vessel)

organ system level

unified group of organs and tissues work together to perform a specific function (ie blood vessels, blood, and heart form cardiovascular system)

organismal level

whole person is made up of all the lower levels working interdependently

how we know something is alive (5)

1. composed of single cell or multicell

2. at least physical and chemical machines

3. respond to short term changes in their environment

4. grow and reproduce

5. adapt to long term changes in environment through natural selection

homeostasis

the body’s ability to maintain a stable internal environment despite changes in external conditions. utilizes mechanisms to regulate factors like temperature, pH, and blood sugar levels. this stable environment allows all body cells to function properly. use feedback loops to maintain homeostasis.

boundary organ concept

organs that control boundaries of internal liquid and external environment by exchanging materials into and out of the body. these boundaries are maintained because internal and external environment must remain distinct.

5 examples of boundary organ systems

1. respiratory system (in O2, out CO2)

2. digestive system (in nutrients, out waste)

3. reproductive system (in genetic material, out waste and baby)

4. urinary system (in nutrients, out waste),

5. integumentary system (out sweat, in vitamin D)

most common feedback loop for homeostasis

negative feedback loop

negative feedback loop definition

response is opposite of stimulus

positive feedback loop definition

response amplifies stimulus until an endpoint is reached

negative feedback loop examples

1. regulating body temperature: if it is cold, your body shivers, body temp rises, and the stimulus ends. body is back in homeostasis.

2. regulating blood pressure: inc BP, response is to dilate arterioles and slow heart, therefore BP is then lowered, back to homeostasis

positive feedback loop examples

1. childbirth: baby trying to get out stretches cervix, brain sends oxytocin to increase contractions, then cervix stretches more.

2. cut and formation of platelet plug: bleed, bleeding continues until plug forms and bleeding stops

body fluid compartments + function

spaces where fluids are distributed within the body to maintain homeostasis

intracellular fluid (ICF) location

fluid within cells (aka cytosol)

extracellular fluid (ECF)

Location: fluid outside cells

intercellular fluid

fluid between cells; part of ECF; aka tissue or interstitial fluid

plasma

fluid part of blood; part of ECF

homeostasis of body fluids

composition of fluids changes as substances move between compartments. small nutrients, oxygen, ions, and wastes move in both directions across capillary walls.

percentage ECF

33%

percent ICF

67%

role of circulatory system in homeostasis of body fluids

interstitial fluid in A affects B through plasma/circulatory system (moving)

active transport

low to high

passive transport

high to low

active transport example

pump uses ATP to keep Na+ out of cell and K+ in

capillaries

aka blood vessels; have tiny diffusion holes to let things in/out for homeostasis

feedback loop: receptor

monitors a controlled condition

feedback loop: control center

determines next action

feedback loop: effector

recieves directions from control center and produces response that changes the controlled condition to bring system back into homeostasis

ICF composition

rich in K+, Mg+, phosphate ions, proteins

ICF function

medium for cell metabolism, enzyme reactions, cellular processes

ECF composition

plasma and IF; rich in Na+, proteins

ECF function

medium for exchange of products between cells and rest of body; ie transporting oxygen from blood to cells