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BSC_2011Ch40Tissues - BSC 2011 Dr Presley Chapter 40...

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BSC 2011 Chapter 40 Dr. Presley Sadava9th Ch 40 1 of 11 HOMEOSTASIS & ANIMAL TISSUES BACKGROUND INFO Theme : form fits function Anatomy = study of structure of the organism Physiology = study of the functions that occur in an organism Larger organisms supply their cells via an internal environment consisting of extracellular fluids HOMEOSTASIS = maintenance of relatively constant conditions in the internal environment. - involves control and regulation in response to changes in external and internal envir. - regulatory systems: mainly the nervous and endocrine Fig 40.2, p. 834 - not as great a problem in small multicellular animals that exchange directly with their external environment REGULATING THE INTERNAL ENVIRONMENT internal environment = interstitial fluid (tissue fluid) which surrounds each living cell. HOMEOSTASIS = “Steady-state” - body attempts to maintain a stable internal condition with certain physiological tolerances even though the external and internal environments are constantly changing - feedback mechanisms – how body responds to stimuli (changes in the envir.) - components: 1) sensory receptor picks up stimulus 2) sensory neuron to integration center 3) integration center , part of central nervous system that interprets the input message; compares current input with set point; determines if error signal; determines action needed for error correction 4) motor neuron to the responder 5) action by effector (muscle or gland) - set point – what the body considers the “normal” - feedforward information – information that allows changes in anticipation of the stimulus, changes the set point as increased heart rate at start of race, Fig 40.2, p. 834 - negative feedback – response will be to reduce or reverse the stimulus - an “error signal” indicates a falling off from the “set point”; moves for correction - examples: 1) body temperature : Stimulus : High temp —> Response : sweat to lower temperature, -vasodilation to increase heat loss by radiation Stimulus : Low temp —> Response: shiver to raise temperature, -vasoconstriction to reduce heat loss by radiation 2) blood glucose level Stimulus : High glucose —> Response : secretion of insulin, causes cells to take up glucose from blood
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BSC 2011 Chapter 40 Dr. Presley Sadava9th Ch 40 2 of 11 - positive feedback – regulatory system responds by amplifying the stimulus - less common than negative feedback - examples: 1) child birth with increasing frequency and force of uterine contractions; 2) blood clotting; 3) urination; 4) vomiting Moving on up the structural hierarchy in living things: Tissues – Organs – Organ Systems – Organism TISSUE – A group of cells which perform a specific function and is derived from the same embryonic tissue - four types of animal tissues : Mader Lab manual has best pictures, Ex 25 1) epithelial tissues Fig 40.3. p. 835 2) muscle tissues Fig 40.4. p. 836 3) connective tissues Fig 40.5. p. 837 4) nervous tissue Fig 40.6. p. 837
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BSC_2011Ch40Tissues - BSC 2011 Dr Presley Chapter 40...

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