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 life o Cytology o Histology

Levels of Organization

Homeostasis Objectives: 1.Significance of homeostasis 2.Positive and negative feedback

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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 PNS o Effectors and response after sympathetic disruption of homeostasis occurs

Two ways to maintain homeostasis o Negative feedback o 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 Answer o Yes, because the response counteracts the stimulus o 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 examples o Childbirth o Blood clotting o Sexual orgasm o 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:// tml

Diffusion: Anatomy example o Oxygen gas enter body and blood stream o Carbon dioxide leave blood and body

Diffusion across membranes o Molecules that dissolve in lipids can cross the lipid bilayer through diffusion. Example: O 2 CO 2 H 2 O

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 connection o Excess water versus dehydration o 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 cytosol o solution outside the cell is less concentrated than inside the cell o water moves into the cell o Hypertonic to the cytosol o solution outside the cell is more concentrated than inside the cell o water moves out of the cell o Isotonic o concentrations are equal o osis.htm osis.htm

What about the molecules that cant 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 cant get through the lipid bilayer o They must use the proteins embedded in the lipid bilayer

Facilitated transport o 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 Neurons gated Na+ and K+ channels o Ca+ channels in nerve and muscle cells

Active transport o Requires energy to transport molecules across a cells membrane Ex. 1 Membrane proteins may serve as pumps to push ions across the cell against the concentration gradient o Examples of pumps? o Na+/K+ pump in neurons

Active Transport (cont) Ex. 2 Exocyotosis – the cell excretes wastes, chemicals or other products by releasing them from vesicles o Where have we seen this? o Release of neurotransmitters Ex 3 Endocytosis – the cell takes in molecules or food by engulfing it o We will see this with immune system and WBCs