Ch 1 The Study of Body Function Flashcards
Negative Feedback Loops
do you know this?
hormones are secreted in response to nerve stimulation and stimulation by other hormones
Pathophysiology
how physiological processes are altered in disease and injury
Antagonistic Effectors
“push-pull” effect. not only turn on one sensor but turn on one and off the other. AC and heater example. most factors in the internal environment are controlled by several effectors, which often have antagonistic actions
some examples (with their explanations) of positive feedback loops are:
Rare amplifications that causes an “avalanche”
Defication- triggered by feces stretching the walls of the rectum
Heart Attack- triggered by a blockage in the coronary arteries, reduces blood flow
Blood Clotting (terminated by negative feedback loop)
Ovulation- estrogen stimulates women’s pituitary glands to secrete LH (luteinizing hormone)
Parturition- contraction of the uterus stimulated by the pituitary hormone “oxytocin” and the secretion of oxytocin is increased by sensory feedback from contraction of the uterus
Describe the negative feedback loop of EATING
Eating causes a rise in the blood glucose— stimulates secretion of insulin (produces a lowering of blood glucose)— cellular uptake of glucose— blood glucose level decreases to normal
Describe the negative feedback loop of FASTING
fasting causes a decrease of blood glucose levels— stimulates the inhibition of insulin (prevents muscle, liver, and adipose cells from taking too much glucose from the blood)— also stimulates secretion of the hormone antagonistic to insulin GLUCAGON.
Glucagon
antagonistic effector to insulin, secretion stimulated due to fasting and a lowering of blood glucose.
Stimulates processes in the liver (breakdown of a stored starch-like molecule called GLYCOGEN that causes the liver to secrete glucose into the blood) which is broken down by hydrolysis
Primary tissues include:
Muscle
Nervous
Epithelial
Connective
Organs and Systems
grouping of primary tissue (2 or more kinds) makes organs, organs grouped together by common function: system
Muscle Tissue
specialized for contraction 3 types: Skelatal Cardiac Smooth
Skeletal Muscle
Volantary
Striated
attached to bones at both ends usually. (by tendons)
4th week of development, separate cells called myoblasts fuse together to form skeletal muscle fibers or myofibers.
-Arranged in bundles of fibers. fibers are controlled individually to give a graded response
each myofiber is a syncytium (a multinucleate mass formed from the union of separate cells- myoblasts)
Cardiac Muscle
- Striated
- NOT under conscious control
- myocardial cells are short connected by INTERCALATED DISCS (couple myocardial cells together mechanically AND electrically)
- thus cannot produce a graded response
Smooth Muscle
- NOT Striated
- NOT under conscious control
- found in digestive tract, blood vessels, bronchioles, ducts of urinary and reproductive systems
- circular arrangements of smooth muscle create a LUMEN (cavity) when the muscle cells contract. for example PERISTALSIS (of the digestive tract)
Nervous Tissue consists of what two types of cells?
Neuroglial cells and neurons
Neuroglial Cells
- Provides the neurons with structural support
- 5 X mor abundant than neurons
- maintain the ability to divide by mitosis throughout life (result of most cancers in the brain)
- recently found to cooperate with neurons in chemical neurotransmission and to have many other roles of the brain and spinal cord
- binds neurons together
- modify the extracellular environment of the nervous system, and influence the nourishment and electrical activity of neurons
Neurons
1) Cell body
- contains the nucleus and serves as the metabolic center of cell
2) Dentrites
3) Axons
