Lecture 1 Homeostasis Flashcards
Human Physiology
Study of functional organization of the human body
*function involving cells
Homeostasis
The maintenance of nearly constant conditions in the internal environment
*Internal enviro is constantly changing
Negative Feedback Loops
An increase in some parameter (ie. bp) causes a response that results in a decrease in that parameter.
Ex. arterial blood pressure
Regulation of arterial blood pressure
Ex of negative feedback loop
- baroreceptors sense increase in arterial pressure
- Baroreceptors send inhibitory signals to vasomotor receptors in medulla
- Heart pumping capacity reduced and blood vessels dilate
- Arterial pressure decreases
Positive Feedback Loop
An increase in some parameter causes a response that continues to increase that same parameter
Ex. childbirth
Gain definition
the degree of effectiveness with which a control system maintains constant conditions
*how effective the feedback loop is
Gain equation
correction/error
Cell membranes
Separate intracellular from extracellular environments and regulate what enters and leaves the cell
Unit membrane
All cell membranes have this same basic structure. *biphospholipid layer with cholesterol inserted among the phospholipid
% of phospholipid layer is cholesterol
50%
2 types of proteins associated with the membrane
- Integral - form channels, help maintain homeostasis
2. Peripheral - loosely attached to surface of membrane, easily removed
Integral Proteins
Either inserted into the membrane on one side or other or pass all the way through and are exposed on either side of the membrane
- many transport, form channels, help maintain homeostasis
- If in middle must have hydrophobic region, and hydrophillic regions on extra/intra
Peripheral Proteins
Loosely attached to one surface of the membrane or the other and are easily removed.
Anything in intra or extra has to be hydrophillic
Plasma Membrane
Serves as a selective filter and limits what can pass from one side to the other
*Lipid soluble substances can generally pass readily across the membrane
Plasma Membrane Functions
- Selective filter
- Integral role in defining the intracellular and extracellular fluid composition (most imp fxn)
- Info exchange between the cell and its enviro
- Involved in exocytosis and endocytosis
Most important function of plasma membrane
An integral role in defining the intracellular and extracellular fluid composition
6 membrane bound cellular organelles
- Nucleus
- Endoplasmic reticulum
- Golgi apparatus
- Mitochondria
- Lysosomes
- Peroxisomes and endosomes
Are ribosomes organelles?
No. They are not membrane bound. Organelles are membrane bound
Cytosol
Cytoplasm without the organelles
Endocytosis includes these two things
- pinocytosis
2. phagocytosis
Endocytosis
Coated pits (with clathrin) with or without receptors Form phagocytic vesicles
Phagocytic vesicles
Formed by endocytosis
Coated with Clathrin and engulfed into cell. Actin/myosin help pinch it off
Cellular Digestion
Involves lysosomes
Lysosomes and digestion
- contain hydrolytic enzymes at a low pH
- Primary lysosomes fuse with phagocytic vesicles to form secondary lysosomes
- Undigested material is left behind within residual bodies
- Residual bodies may be eliminated via exocytosis
