Presentation on theme: "Physiology, Homeostasis, and Temperature Regulation"— Presentation transcript:
1 Physiology, Homeostasis, and Temperature Regulation 29Physiology, Homeostasis, and Temperature Regulation
2 Homeostasis such as temperature, pH, and ion concentration. the maintenance of stable conditions in an internal environment.Cells are specialized for maintaining the internal environmentsuch as temperature, pH, and ion concentration.Specialized cells evolve into tissues, organs, and physiological systems that serve specific functions to maintain homeostasis
3 Multicellular organisms need a stable fluid environment Concept 29.1 Multicellular Animals Require a Stable Internal EnvironmentMulticellular organisms need a stable fluid environmentIntracellular fluid – within the cells (mostly water)extracellular fluidwhich includes blood plasma and interstitial fluid that bathes each cell.APPLY THE CONCEPT Multicellular animals have an internal environment of extracellular fluid
5 Four types of tissue: Epithelial Connective Nervous Muscle Cells make up tissuesFour types of tissue:EpithelialConnectiveNervousMuscle
6 Epithelial Tissueare sheets of tightly connected epithelial cells that cover inner and outer body surfaces.Some line blood vessels and hollow organs.Some secrete substances such as hormones or sweat, or serve transport functions for nutrients.Others serve sensory functions of smell, taste, and touch.
7 Connective Tissueare dispersed cells in a secreted extracellular matrix.The composition of the matrix differentiates the types of connective tissues.Collagen and elastin provide strength and elasticity to cartilage.Bone matrix is mineralized for strength while the matrix of blood cells—plasma—is liquid.Adipose tissue, made of fat cells, has little matrix.
8 contain two basic cell types— neurons and glial cells. Nervous Tissuecontain two basic cell types— neurons and glial cells.Neurons generate and conduct electrical signals, or nerve impulses, throughout the body.They are units of the central and peripheral nervous systems and communicate via chemicals, neurotransmitters.Glial cells provide support for neuronal function.
9 consist of elongated cells that generate force and cause movement. Muscle Tissuesconsist of elongated cells that generate force and cause movement.Three types of muscle tissues:Skeletal—responsible for locomotion and movementCardiac—makes up the heart and generates heartbeat and blood flowSmooth—involved in movement and generation of forces in internal organs
10 To maintain homeostasis: InformationControlSet point – a referenceFeedback – what is happeningError Signal – any difference between set pt. and feedbackNegative FeedbackPositive FeedbackFeedforward InformationRegulationSensorEffectors
11 Figure 29.3 Control, Regulation, and Feedback Feed forward – changes set point!Set pointfeedbackRegulatory system
12 Obtain, integrate, and process information Concept 29.2 Physiological Regulation Achieves Homeostasis of the Internal EnvironmentRegulatory systems:Obtain, integrate, and process informationIssue commands to controlled systemsContain sensors to provide feedback information that is compared to the set pointRegulatory systems then issue commands to effectors that effect changes in the internal environment.Effectors are controlled systems because they are controlled by regulatory systems.
13 Sensory information in regulatory systems includes: Negative feedback Concept 29.2 Physiological Regulation Achieves Homeostasis of the Internal EnvironmentSensory information in regulatory systems includes:Negative feedbackPositive feedbackFeedforward information
14 Stabilizes Negative feedback: Concept 29.2 Physiological Regulation Achieves Homeostasis of the Internal EnvironmentNegative feedback:Causes effectors to counteract the influence that creates an error signalResults in a movement back to set pointExample: driving too fast – causes you to slow down!Stabilizes
15 Reach limit, then terminate Positive FeedbackPositive feedback:Amplifies a responseIncreases deviation from a set pointExamples: sexual behavior – little stimulation increases behavior responseReach limit, then terminate
16 Feedforward Information Anticipates internal changes and changes the set point.Example: seeing deer changes set point to lower speed
18 Concept 29.3 Living Systems Are Temperature-Sensitive Physiological processes are temperature- sensitive and increase their rate at higher temperatures.Q10 describes temperature-sensitivity as the quotient of the rate of a reaction at one temperature divided by the rate of the same reaction at a lower temperature (10 degrees)Q10 = RT/RT–10
19 Figure 29.4 Q10 and Reaction Rate Rxn rates are doubledOr tripled as temp.Increases by 10=1, not temp. sensitive
20 if Q10 < 1 the rate drops with an increase in T if Q10 > 1 then the rx rate increases with temperature
21 Calculate the Q10 for the following scenario A rate of an enzyme worked at a rate of 76 at 10 degrees Celsius and it worked at a rate of 145 at 20 degrees Celsius.145/76 = (the exponent cancels out 10/(20-10)The temperature for these calculations do NOT always have to be 10 apart. See formula.
22 Animals can acclimatize to seasonal temperature changes Animals can regulate their body temperatureEctotherms – depends on temperature of environmentEndotherms – maintain constant body temperature independent of external temperatures
23 Figure 29.5 Ectotherms and Endotherms React Differently to Environmental Temperatures (Part 1)
24 Figure 29.5 Ectotherms and Endotherms React Differently to Environmental Temperatures (Part 2) In the thermoneutral zone the metabolic rate is low and independent of temperature.The basal metabolic rate (BMR) is the metabolic rate of a resting animal at a temperature within the thermoneutral zone.
25 Concept 29.4Animals Control Body Temperature by Altering Rates of Heat Gain and LossMetabolism—conversion of ATP to do work produces heatRadiation—warmer objects lose heat to cooler objects by radiationConvection—heat is lost when wind is cooler than body surface temperatureConduction—heat is transferred when objects of different temperatures come into contactEvaporation—heat is lost and body is cooled when water leaves the body
26 expend most of their energy pumping ions across membranes. Mammals and Birds (Endotherms) have high rates of metabolic heat productionexpend most of their energy pumping ions across membranes.Cells are “leakier” to ions than cells of ectotherms.Endotherms spend more energy and release more heat to maintain ion concentration gradients.LINK Review the mechanisms of ion transport described in Concepts 5.2 and 5.3
27 Mammals produce heat in two ways: Concept 29.4 Animals Control Body Temperature by Altering Rates of Heat Gain and LossIf environmental temperature (Ta) falls below an endotherm’s lower critical temperature, animal must produce heat or body temperature (Tb) will fall.Mammals produce heat in two ways:Shivering —skeletal muscles contract and release energy from ATP as heat.Nonshivering heat production—in adipose tissue called brown fat. –*hibernationSee Chapter 6, p. 104
28 Brown fat has lots of mitochondria and a rich blood supply! Figure Brown FatBrown fat has lots of mitochondria and a rich blood supply!
29 The BMR per gram of tissue increases as animals get smaller. Concept 29.4 Animals Control Body Temperature by Altering Rates of Heat Gain and LossThe basal metabolic rate (BMR) is correlated with body size and environmental temperature.The BMR per gram of tissue increases as animals get smaller.Example: A gram of mouse tissue uses energy at a rate 20 times greater than a gram of elephant tissue.
30 Reducing heat loss is important in cold climates. Concept 29.4 Animals Control Body Temperature by Altering Rates of Heat Gain and LossReducing heat loss is important in cold climates.Some cold-climate species have a smaller surface area than warm-climate relatives.Rounder body shapes and shorter appendages reduce surface area-to- volume ratios.
31 Figure 29.9 Anatomical Adaptations to Climate (Part 1) Short FurLimited body insulationLarge ears and long limbs allow heat to radiate out
32 Figure 29.9 Anatomical Adaptations to Climate (Part 2) Thick coat of insulating furSmall ears, short limbs, rounded body shape give it a smaller surface area to volume ratio – so less heat can be lost
33 Other adaptations to reducing heat loss include: Concept 29.4 Animals Control Body Temperature by Altering Rates of Heat Gain and LossOther adaptations to reducing heat loss include:Increased thermal insulation with fur, feathers, or fatAbility to decrease blood flow to the skin by constricting blood vessels
34 Insects contract their flight muscles Concept 29.4 Animals Control Body Temperature by Altering Rates of Heat Gain and LossSome ectotherms are able to raise their body temperature by producing heat:Insects contract their flight musclesHoneybees regulate temperature as a group, adjusting individual heat and position in the cluster so that larvae are kept warm
35 Concept 29.4 Animals Control Body Temperature by Altering Rates of Heat Gain and Loss Both endotherms and ectotherms may use behavioral regulation to maintain body temperature.Examples: Lizard moving into sun or shade, or elephant spraying itself with water or dust
36 Thermostat in MammalsIn vertebrate brains, the hypothalamus is the major center of the thermostat.The temperature of the hypothalamus can be the main feedback to the thermostat.See Figure 30.7 A
37 Cooling the hypothalamus can cause body temperature to rise by: Concept 29.5 A Thermostat in the Brain Regulates Mammalian Body TemperatureCooling the hypothalamus can cause body temperature to rise by:Constricting blood vessels to the skinIncreasing metabolic rateWarming the hypothalamus can lower body temperature by:Dilating blood vessels to the skinSweating or pantingSee Figure 30.7 A
38 Figure 29.13 The Hypothalmus Regulates Body Temperature (Part 1)
39 Other factors can change hypothalamic set points: Concept 29.5 A Thermostat in the Brain Regulates Mammalian Body TemperatureThe temperature of the hypothalamus is a negative feedback signal—variability from its set point can trigger thermoregulatory responses.Other factors can change hypothalamic set points:Change in skin temperatureWakefulness or sleepCircadian rhythm—a daily internal cycleANIMATED TUTORIAL 29.1 The Hypothalamus
40 Fever is a an adaptive response to help fight pathogens. Concept 29.5 A Thermostat in the Brain Regulates Mammalian Body TemperatureFever is a an adaptive response to help fight pathogens.The rise in body temperature is caused by a rise in the set point for metabolic heat production.Some animals lower their temperature during inactive periods to conserve energy—daily torpor.Long-lasting regulated hypothermia— hibernation