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- Study of biological function
- -Largely concerned w/ homeostasis
- -Emphasizes mechanisms of how things work
- -Explained via cause and effect (NTL analogue)
- -Derived from scientific experiments
- Concerns how disease/injury affects physiological processes
- Aids understanding of normal processes
Describe the phases of clinical trials.
- Phase I: test for side effects
- Phase II: test effectiveness on target subject
- Phase III: increase sample size and diversify (e.g. expand to different sexes, age groups, ethnicities, and people with more than one health condition). FDA determines approval for drug sale.
- Phase IV: test other applications of the drug
- A state of relative constancy of the internal environment
- -This is dynamic (oscillatory)
- -Main purpose of physiological mechanics is maintenance of this
- -Deviations indicate disease
- -Mediated via negative feedback loops
Negative Feedback Loops
Sensors acquire information and send to the integrating center, which assesses changes around a set point. The integrating center sends instructions to an effector, which can make the appropriate adjustments to counter the change in the set point.
Sensors → integrating center → effectors
Negative Feedback Loop Mechanisms
- Moves in opposite direction of change
- Makes the change from the set point smaller
- Reverses change from the set point
- A continuous process, always making fine adjustments to stay in homeostasis
Opposte direction → ↓∆(set pt) → Reverses ∆(set pt) → Continually making fine adjustments
- •Homeostasis is maintained by opposing effectors that move conditions in opposite directions
- 1 - Maintained within a normal range, or
- dynamic constancy
- •Hot = sweat
- •Cold = shiver
- •Actions produced go in opposite direction
- of state
- The end product in a process stimulates the process
- The action amplifies the changes that stimulated the effectors
- Could not work alone, but it does contribute to many neg. feedback loops (e.g. blood clotting).
Cells within the organ sense a change and signal neighboring cells to respond appropriately
The brain (or other organs) regulates an organ using the endocrine or nervous system
- •Nervous system "innervates" organs with
- nerve fibers
- •Endocrine system releases hormones into
- the blood, upon which they are
- transported to multiple target organs
Feedback Control of Hormone Secretion
- Hormones secreted in response to specific stimuli
- Secretion can be inhibited by its own effects (e.g. glucose/insulin)
- Neg. feedback (NF) inhibition usually involves an antagonist to make sure homeostasis is maintained within normal levels
•Each tissue has particular structures & fcns. that dictate the physiology of the organ
Part of: muscular tissue
Early muscle cells; during embryonic development these cells fuse together forming skeletal muscle fibers, known as myofibers
Part of: muscular tissue (cardiac)
- •Characteristic of heart muscle
- •Couple myocardial cells together mechanically and electrically
Connective Tissue (CT) Proper
Many different types:
- 1-Loose: protein fibers composed of collagen are scattered loosely in the ground substance
- •Provides space for blood vessels (BVs),
- nerve fibers, and other strucs.
- 2-Dense regular: densely packed collagen fibers w/ little room for cells and ground substance
- •Tendons & ligaments fall in this category
3-Adipose: serves for insulation, energy storage and protection/cushioning
4-Dense irregular: collagen fibers densely packed in many different arrangements
Describe the skin.
The largest organ in the body, consisting of a multitude of layers containing all four primary tissues.
Epidermis: keratinized stratified squamous epithelium to protect against water loss and abrasion.
Dermis: dense irregular CT containing exocrine glands, hair follicles, sense receptors, and BVs.
Hypodermis: adipose tissue for padding and insulation.
What constitutes an organ?
2+ tissues that serve different fcns. in the organ; skin is the largest.
Body fluid compartments.
- Intracellular: area inside the cells; contains 65% of total body H2O.
- Extracellular: area outside the cell, examples include blood plasma and interstitial fluid.
Both compartments are filled primarily with water and are separated by membranes.