Lecture 7B Flashcards
Homeostatic control components
Stimulus, Sensor, Control center, Effector response
Negative feedback control
Most common feedback system. The body responds to stimulus by working against it. (eg temperature lowers, body initiates shivering to warm itself)
Positive feedback control
Least common feedback system. The body repeats a stimulus until it is complete. (eg birth contractions, blood clotting, breast feeding, inflammation)
Countercurrent exchange
Transfer of heat or solutes between currents travelling in opposite directions
Regulator Organism
Organism regulates internal conditions against external conditions. (eg warmblooded)
Conformer Organism
Organism conforms to external conditions (eg coldblooded)
Receptor
Structures/cells that respond to certain conditions (eg light, chemical)
Cellular Signaling Cascade
One cellular response triggers more cellular responses.
Two cellular materials vulnerable to temperature change
Enzymes and Cellular Membrane
Heat Shock Proteins
Part of a cells heat shock response, work to refold misfolded proteins.
Four major strategies for tolerating temperature extremes or changes
Circulation, Acclimation, Physiology, and Behavior
Brown Fat
Darker colored adipose tissue; has many blood vessels and mitochondria; works to convert food energy into heat energy.
Four heat transfers
Radiation - heat emanating from a source (the sun)
Evaporation - liquid vaporisation reduces the heat on the surface of the skin
Conduction - heat transfer through touching an object
Convection - the movement of warmer water or air rising and cooler water or air sinking causing heat transfer
Primary function of endocrine system
Communicate/coordinate through hormones
Hormone
Molecular signals sent to distant organs usually through the bloodstream.
Water soluble hormones
bind to receptors in the plasma membrane; can initiate a signaling cascade; generally have a more rapid or brief impact on the target cell
Lipid soluble hormones
bind to receptors within the cell; affect gene expression; aka steroids
Three mechanisms that stimulate hormone release
nervous system, other hormones, or blood composition/volume
Number of hormones released by pituitary gland
eight
Region of brain that controls hormone release
Hypothalamus
Anterior v. Posterior Pituitary hormone release stimulus
Anterior: stimulated by hypothalamus
Posterior: stores hormones produced by hypothalamus
Fight or Flight response
triggered by epinephrine (adrenaline)
Epinephrine tissue impacts
Liver - Glycogen deposits are broken down and glucose is released into the bloodstream
Smooth muscle in airway - cells relax, increasing air flow into and out of the lungs
Smooth muscle in blood vessel that supplies intestines - cells constrict, decreasing blood flow to intestines
Osmosis
movement of a concentration from high to low across a membrane (chemical, heat)
