BIO 203 Lecture Notes - Lecture 4: Tonicity, Lipid Bilayer, Sodium Chloride
16 Nov 2016
School
Department
Course
Professor
Lecture 4
Heterotherms
● Animals capable of varying degrees of endothermic heat production
● Temporal Heterotherms - TB varies over time
○ Hibernation, torpor, TB fluctuations during the day
● Regional Heterotherms - different parts of the body at different temperatures
○ Ectotherms that maintain core temperature higher than Tamb (tuna, large sharks)
○ Testes in some mammals (canines, humans)
The Hypothalamus - Mammal’s Thermostat
● Henry G. Barbour (1912)
○ Implanted a small temperature controlled probe into different parts of the rabbit brain
○ Evoked strong thermoresponses only when used to heat and cool the hypothalamus
■ Cooling → ⇧ MR and ⇧ TB
■ Heating → ⇩ MR and ⇩ TB
■ Highly sensitive
● Hypothalamus integrates all of the temperature related info and orchestrates the systemic
response
Pre-Optic/Anterior Hypothalamus (Integrator)
Fever
find more resources at oneclass.com
find more resources at oneclass.com
● Hypothalamic thermoregulatory center is very sensitive to pyrogens (fever producing
subsstances)
○ Pyrogens raise the set-point in the hypothalamic regulatory center
○ Exogenous Pyrogens - very potent polysaccharides produced by gram negative bacteria
○ Endogenous Pyrogens - heat labile proteins produced by leukocytes (white blood cells)
■ released in response to exogenous pyrogens
● Exogenous Pyrogens raise TB by:
○ Directly acting on hypothalamic thermoregulatory center
○ Indirectly by stimulating the release of endogenous pyrogens
Water and Ion Balance (Osmolarity and Body Volume)
● Basic Biological Need
○ All cells need to exist in an aqueous environment (BP #1)
○ H2O and Salts (ions) - need to be kept relatively constant
■ Homeostasis/Budget
○ Tightly associated with temperature regulation
■ Evaporative cooling critical to maintaining TB under conditions of high Tamb
and/or high MR
● During exercise
● Body Fluids
○ Intracellular Fluids (ICF) - high K+
○ Extracellular Fluids (ECF) - high Na+
■ Interstitial fluid (IF)
■ Plasma - non cellular liquid portion of blood
○ Body Fluid (BF) = ECF
○ Distribution of Fluids
Diffusion
● Move down concentration gradient
● Passive process (no input of energy required)
● Random thermal motions (function of temperature)
● Transport Equation
Movement of Solutes Through Membranes
● Semi-permeable membranes (selective permeability)
○ Permeable → allows substances to pass
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Animals capable of varying degrees of endothermic heat production. Temporal heterotherms - tb varies over time. Hibernation, torpor, tb fluctuations during the day. Regional heterotherms - different parts of the body at different temperatures. Ectotherms that maintain core temperature higher than tamb (tuna, large sharks) Implanted a small temperature controlled probe into different parts of the rabbit brain. Evoked strong thermoresponses only when used to heat and cool the hypothalamus. Cooling mr and tb. Heating mr and tb. Hypothalamus integrates all of the temperature related info and orchestrates the systemic response. Hypothalamic thermoregulatory center is very sensitive to pyrogens (fever producing subsstances) Pyrogens raise the set-point in the hypothalamic regulatory center. Exogenous pyrogens - very potent polysaccharides produced by gram negative bacteria. Endogenous pyrogens - heat labile proteins produced by leukocytes (white blood cells) released in response to exogenous pyrogens. Indirectly by stimulating the release of endogenous pyrogens. Water and ion balance (osmolarity and body volume)
