introduction to anatomy and physiology

Introduction to Anatomy and Physiology

anatomy = “a cutting open”o Study of internal and

external structures of the body and the physical relationship between body parts

o Ex – a particular bone attached to a muscle

physiology o Study of the function of

anatomical structures; considers both physical and chemical processes

o Ex. how a muscle contracts to move the bone

cell: basic unit of lifeo Cytologyo Histology

Levels of Organization

Homeostasis

Objectives:1. Significance of homeostasis

2. Positive and negative feedback

Start here

Lots of examples of negative feedback loops, few positive loops

For test be able to analyze:o Calcium homeostasis (page 132)o Body temperature (page 7)o Water regulation (refer to notes)o Control center for sympathetic and

parasympathetic divisions of PNSo Effectors and response after

sympathetic disruption of homeostasis occurs

Two ways to maintain homeostasis

o Negative feedbacko Positive feedback

Negative Feedback: example body temperature

Q1: compare response to original stimulus

o Answer:o The response by the effectors

is antagonistic (opposite) of the stimulus

Stimulus = body temp ↑Response = body temp ↓

Q2: homeostasis restored? How do you know?

o Answero Yes, because the response

counteracts the stimuluso Brings back balance

Positive Feedback: example labor contractions

Q3: compare response and stimulus in

positive feedback o Answer

o The response acts to heighten or increase the stimulus

Stimulus = ↑ distortion of uterus

Response= ↑ distortion and contraction of

uterus

Q4: Is homeostasis restored in this example? How do you

know?o Answer:

o No, homeostasis is continually disrupted o This is a good thing in this case b/c

returning to homeostasis would cause the birthing process to stop.

o The positive feedback loop will continue until birth is complete.

Positive feedback exampleso Childbirtho Blood clottingo Sexual orgasmo Milk production from

mammary glands

Cellular homeostasis

Every level of organization within the body must maintain homeostasis

Phospholipid Bilayer

Diffusion

o Diffusion is the movement of molecules from a higher concentration to a lower concentration.

o The difference in concentration of two solutions is called the concentration gradient

o Demonstration: food coloring in water

ttp://www.biosci.ohiou.edu/introbioslab/Bios170/diffusion/Diffusion.html

Diffusion: Anatomy exampleo Oxygen gas enter body and

blood streamo Carbon dioxide leave blood

and body

Diffusion across membranes

o Molecules that dissolve in lipids can cross the lipid bilayer through diffusion. Example: O2

CO2 H2O

Osmosis

o Think back to solutions: solutes and solvents

o Osmosis is the process by which water molecules diffuse across a cell membrane from an area of lower solute concentration to an area of higher solute concentration.

o Direction of movement depends on relative concentrations of solutions.

Osmosis: anatomy connectiono Excess water versus

dehydrationo Kidneys help to rid excess

water as urine = osmosis of water out of blood (high) into kidneys (low)

Direction of movement into cells

o Hypotonic to the cytosolo solution outside the cell is less concentrated than

inside the cell

o water moves into the cell

o Hypertonic to the cytosolo solution outside the cell is more concentrated than

inside the cello water moves out of the cell

o Isotonico concentrations are equal

ohttp://www.tvdsb.on.ca/westmin/science/sbi3a1/Cells/Osmosis.htm

What about the molecules that can’t pass through the membrane freely?

o Glucose, Na+, Ca+, K+ and lots of other molecules need to get into and out of the cell but can’t get through the lipid bilayer

o They must use the proteins embedded in the lipid bilayer

Facilitated transporto Protein channels embedded

in the cell membrane allow ions and other molecules to diffuse into and out of a cell

o Where have we seen facilitate diffusion in action?o Neuron’s gated Na+ and K+

channelso Ca+ channels in nerve and

muscle cells

Active transporto Requires energy to

transport molecules across a cell’s membrane

Ex. 1 Membrane proteins may serve as pumps to push ions across the cell against the concentration gradiento Examples of pumps?o Na+/K+ pump in neurons

Active Transport (con’t)Ex. 2 Exocyotosis – the cell

excretes wastes, chemicals or other products by releasing them from vesicleso Where have we seen this?o Release of neurotransmitters

Ex 3 Endocytosis – the cell takes in molecules or food by engulfing ito We will see this with immune

system and WBCs