Chapter 29

 Animals are mostly water  Intracellular Fluid (ICF)  Most of water  Within cells  Extracellular Fluid (ECF)  The rest of the water, interstitial fluid, plasma, lymph  Interstitial fluid: Bathes cells, nutrients, waste

 Homeostasis  Maintaining stable internal environment  Temperature, pH, ion concentration

 Cells → Tissues → Organs  Specialized cells form tissues  Tissue types  Epithelial  Connective  Nervous  Muscle

 Epithelial cells  Lines body surfaces and organs  Functions  Secretion, selective absorption, protection, transcellular transport and detection of sensation

 Components: Cells, fibers, extracellular matrix  Functions  Store energy, protect organs, provide structural framework, connect tissues  Tissue composition differs based on function

 Composed of two cell types  Neurons  Conduct nerve impulses throughout body  Components of central and peripheral nervous systems  Communicate by chemical neurotransmitters  Glial  Provide support for function

 Function: produce force and create motion  Contractile filaments move across  Changes size of cell → Motion  Three types  Skeletal: Locomotion and movement  Cardiac: Heartbeat  Smooth: Forces in internal organs

 Cells → Tissues→ Organs  Most organs have all four tissue types  Homeostasis depends on organs responding to the demands of the cells

 Information is required to regulate internal environment.  Information=Feedback  Systems are controlled by actions of nervous and endocrine systems

 Set point  Desired level or rate  Error signal  Any difference between the set point and the feedback information

 Anything that receives information processes it and issues commands  Sensor-provides feedback information; eyes, nose, touch, hairs, etc.  Effectors-systems that make the changes

 Most commonly used by regulatory systems  “Negative”- used to counteract a force pushing away from the set point, the change is “negated”  Ex: Sweating from your body temperature being to high cools you down.

 Not as commonly used as negative feedback  Amplifies a response  Increases the deviation from the set point  Sexual behavior- a little stimulation causes an increased behavioral response

 Information used to change a set point  Ex: Squirrels know when cold temperatures are coming, and use this information to change the regulations and hybernate

 Normal cellular function=0-40 degrees C  Most cells adapted to narrow limit  Humans Degrees C

 Most reactions are temperature sensitive  Usually proceed faster at a higher temperature Q 10 –temperature sensitivity coefficient R T –rate of reaction at a certain temperature Also known as “the 10 degree rule” Q 10 = R T /R T–10

 Produce fewer enzymes  Produce enzymes with different optimal temp

 Ectotherms  “heat from the outside”  Use heat from the environment  Invertebrates, Fish, Amphibian, Reptiles

 Endotherms  “heat from inside”  Maintain a higher body temperature  Heat generated metabolically  Birds and Mammals

 Heat budget equation  Heat in : Thermal energy flowing in  Environment and metabolism  Heat out : Thermal energy leaving animal  If heat in ≠ heat out, then body temperature will change  Surface area and temperature are key factors

 Metabolism  Cleaving bonds in ATP  Radiation  Infrared radiation  Convection  Conduction  Evaporation

 Endotherms spend more energy pumping ions across membranes and maintaining concentration gradients  Expenditure of energy releases heat

 If temperature falls below endotherms lower critical temperature, then their body temperature will fall  Heat produced by  Shivering thermogenesis  Nonshivering heat production in brown fat

 Basal metabolic rate (BMR)  Body size and environmental temperature  Increases as animals get smaller

 Cold-climate species  Lower surface area/volume ratio  Insulation with fur  Decrease blood flow to skin  Countercurrent heat exchange  Rounder body shapes have lower ratio

 Fish lose most heat as blood travels through gills  Cold fish use cold blood from gills  Hot fish use countercurrent exchage

 High environmental temperature  Increased blood flow to skin  Evaporation of water through sweating  Active process

 Ectotherms can produce heat  Insects contract flight muscles

 Endotherms and ectotherms both regulate temperature behaviorally

 Hormonal and neural mechanisms control thermoregulatory adaptations  Temperature regulatory system acts as thermostat  Hypothalamus is the center of thermostat

 Cool hypothalamus  Increased metabolic rate  Less blood flow to skin  Warm hypothalamus  More blood flow to skin  Sweating and panting  Negative feedback

 Fever response to pathogens  Animals lower temperature during inactive periods- torpor  Energy conservation  Hibernation  Long lasting regulated hypothermia