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  • Figure 40.3 Contact with the environment.
  • Figure 40.4 Internal exchange surfaces of complex animals.
  • Table 40.1 Organ Systems in Mammals
  • Figure 40.5 Exploring: Structure and Function in Animal Tissues
  • Figure 40.5 Exploring: Structure and Function in Animal Tissues
  • Figure 40.5 Exploring: Structure and Function in Animal Tissues
  • Figure 40.5 Exploring: Structure and Function in Animal Tissues
  • Figure 40.6 Signaling in the endocrine and nervous systems
  • Figure 40.7 The relationship between body and environmental temperatures in an aquatic temperature regulator and an aquatic temperature conformer.
  • Figure 40.8 A nonliving example of temperature regulation: control of room temperature.
  • Figure 40.11 Heat exchange between an organism and its environment.
  • Figure 40.16 The thermostatic function of the hypothalamus in human thermoregulation.
  • Homeostasis bb

    1. 1. AA single-celled protist living in water has a sufficient surface single-celled protist living in water has a sufficient surface area of plasma membrane to service its entire volume of area of plasma membrane to service its entire volume of cytoplasm cytoplasm More complex organisms have highly folded internal surfaces More complex organisms have highly folded internal surfaces for exchanging materials for exchanging materials Mouth Gastrovascular cavity Exchange Exchange Exchange 0.1 mm 1 mm Rate of exchange is proportional to a cell’s surface area while amount of exchange material is proportional to a cell’s volume
    2. 2. Figure 40.4 External environment CO2 O Food 2 Mouth More complex organisms have highly folded internal surfaces for exchanging materials Nutrients 250 µm Respiratory system Heart Digestive system Lung tissue (SEM) Cells Interstitial fluid Circulatory system Excretory system 100 µm Lining of small intestine (SEM) od Anus Unabsorbed matter (feces) Metabolic waste products (nitrogenous waste) Blood vessels in kidney (SEM) 50 µm Blo Animal body In vertebrates, the space between cells is filled with interstitial fluid, which allows for the movement of material into and out of cells
    3. 3. Table 40.1 A complex body plan helps an animal living in a variable environment to maintain a relatively stable internal environment
    4. 4. Tissues are classified into four main categories: epithelial, connective, muscle, and nervous Epithelial Tissue • Epithelial tissue covers the outside of the body and lines the organs and cavities within the body • It contains cells that are closely joined • The shape of epithelial cells may be cuboidal (like dice), columnar (like bricks on end), or squamous (like floor tiles) • The arrangement of epithelial cells may be simple (single cell layer), stratified (multiple tiers of cells), or pseudostratified (a single layer of cells of varying length)
    5. 5. Figure 40.5aa Epithelial Tissue Stratified squamous epithelium Cuboidal epithelium Simple columnar epithelium Simple squamous epithelium Pseudostratified columnar epithelium
    6. 6. Connective Tissue • Connective tissue mainly binds and supports other tissues – It contains sparsely packed cells scattered throughout an extracellular matrix – The matrix consists of fibers in a liquid, jellylike, or solid foundation • There are three types of connective tissue fiber, all made of protein: 1. Collagenous fibers provide strength and flexibility 2. Elastic Fibers stretch and snap back to their original length 3. Reticular fibers join connective tissues to adjacent tissues • Connective tissue contains cells, including  Fibroblasts that secrete the protein of extracellular fibers  Macrophages that are involved in the immune system
    7. 7. • In vertebrates, the fibers and foundation combine to form six major types of connective tissue: – Loose connective tissue binds epithelia to underlying tissues and holds organs in place – Cartilage is a strong and flexible support material – Fibrous connective tissue is found in tendons, which attach muscles to bones, and ligaments, which connect bones at joints – Adipose tissue stores fat for insulation and fuel – Blood is composed of blood cells and cell fragments in blood plasma – Bone is mineralized and forms the skeleton (cartilage, ligaments, tendons, adipose tissue, blood, bone)
    8. 8. Figure 40.5ba Connective Tissue Loose connective tissue Blood Collagenous fiber Plasma 55 µm 120 µm White blood cells Elastic fiber Red blood cells Cartilage Fibrous connective tissue 30 µm 100 µm Chondrocytes Chondroitin sulfate Nuclei Bone 700 µm Central canal Fat droplets Osteon 150 µm Adipose tissue
    9. 9. Muscle tissue consists of long cells called muscle fibers, which contract in response to nerve signals Muscle Tissue Skeletal muscle Nuclei Muscle fiber Sarcomere 100 µm Skeletal muscle, or striated muscle, is responsible for voluntary movement Smooth muscle Nucleus Muscle fibers Cardiac muscle 25 µm Smooth muscle is responsible for involuntary body activities Nucleus Intercalated disk 50 µm Cardiac muscle is responsible for contraction of the heart
    10. 10. Figure 40.5da Nervous tissue senses stimuli and transmits signals throughout the animal Nervous Tissue Neurons Glia Glia 15 µm Neuron: Dendrites Cell body Axons of neurons 40 µm Axon Blood vessel (Fluorescent LM) transmit nerve impulses (Confocal LM) help nourish, insulate and replenish neurons
    11. 11. Coordination and Control • Control and coordination within a body depend on the endocrine system and the nervous system – The endocrine system transmits chemical signals called hormones to receptive cells throughout the body via blood • A hormone may affect one or more regions throughout the body • Hormones are relatively slow acting, but can have long-lasting effects – The nervous system transmits information between specific locations • The information conveyed depends on a signal’s pathway, not the type of signal • Nerve signal transmission is very fast • Nerve impulses can be received by neurons, muscle cells, endocrine cells, and exocrine cells
    12. 12. Figure 40.6
    13. 13. Feedback control maintains the internal environment in many animals • Animals manage their internal environment by regulating or conforming to the external environment – A regulator uses internal control mechanisms to moderate internal change in the face of external, environmental fluctuation – A conformer allows its internal condition to vary with certain external changes – Animals may regulate some environmental variables while conforming to others
    14. 14. Figure 40.7
    15. 15. Homeostasis • Mechanisms of homeostasis moderate changes in the internal environment – For a given variable, fluctuations above or below a set point serve as a stimulus; these are detected by a sensor and trigger a response – The response returns the variable to the set point
    16. 16. Homeostasis can adjust to changes in external environment, a process called acclimatization Figure 40.8
    17. 17. Mechanisms of homeostasis: • Adaptation to the thermal environment: thermoregulation • Adaptation to the osmotic environment: osmoregulation • Strategies for the elimination of waste products of protein catabolism: excretion
    18. 18. Homeostatic processes for thermoregulation involve form, function, and behavior • Thermoregulation is the process by which animals maintain an internal temperature within a tolerable range – Endothermic animals generate heat by metabolism; birds and mammals are endotherms – Ectothermic animals gain heat from external sources; ectotherms include most invertebrates, fishes, amphibians, and nonavian reptiles • In general, ectotherms tolerate greater variation in internal temperature, while endotherms are active at a greater range of external temperatures • Endothermy is more energetically expensive than ectothermy
    19. 19. Variation in Body Temperature • The body temperature of a poikilotherm varies with its environment • The body temperature of a homeotherm is relatively constant • The relationship between heat source and body temperature is not fixed (that is, not all poikilotherms are ectotherms)
    20. 20. 4 physical processes account for heat gain or loss: • • • • 1) Conduction 2) Convection 3) Radiation 4) Evaporation Evaporation & convection are the most variable causes of heat loss.
    21. 21. 4 physical processes account for heat gain or loss: • Conduction is the direct transfer of heat (thermal motion) between molecules of the environment & body surface. – Heat is always conducted from a body of higher temperature to one of lower temperature. – Water is 50 to 100 times more efficient than air in conducting heat. – On a hot day, an animal in cold water cools more rapidly than one on land. • Convection is the transfer of heat by movement of air or liquid past a body surface. – breezes contribute to heat loss from an animal with dry skin.
    22. 22. 4 physical processes account for heat gain or loss: • Radiation is the emission of electromagnetic waves produced by all objects warmer than absolute zero. – It can transfer heat between objects not in direct contact. – For example, an animal can be warmed by the heat radiating from the sun. • Evaporation is the loss of heat from a liquid’s surface that is losing some molecules as gas. - Production of sweat greatly increases evaporative cooling - Can only occur if surrounding air is not saturated with water molecules. –
    23. 23. Organisms exchange heat by four physical processes: radiation, evaporation, convection, and conduction
    24. 24. • Heat regulation in mammals often involves the integumentary system: skin, hair, and nails • Five adaptations help animals thermoregulate: – Insulation = skin, fur, feathers, blubber – Circulatory adaptations = vasodilation and vasoconstriction – Cooling by evaporative heat loss – Behavioral responses – Adjusting metabolic heat production
    25. 25. • The arrangement of blood vessels in many marine mammals and birds allows for countercurrent exchange • Countercurrent heat exchangers transfer heat between fluids flowing in opposite directions and reduce heat loss
    26. 26. Behavioral Responses • In winter, many animals bask in the sun or on warm rocks. • In summer, many animals burrow or move to damp areas. • Some animals migrate to more suitable climates.
    27. 27. Adjusting Metabolic Heat Production • Thermogenesis is the adjustment of metabolic heat production to maintain body temperature • Thermogenesis is increased by muscle activity such as moving or shivering – Nonshivering thermogenesis takes place when hormones cause mitochondria to increase their metabolic activity – Some ectotherms can also shiver to increase body temperature
    28. 28. Acclimatization in Thermoregulation • Birds and mammals can vary their insulation to acclimatize to seasonal temperature changes • When temperatures are subzero, some ectotherms produce “antifreeze” compounds to prevent ice formation in their cells
    29. 29. Physiological Thermostats and Fever • Thermoregulation is controlled by a region of the brain called the hypothalamus • The hypothalamus triggers heat loss or heat generating mechanisms • Fever is the result of a change to the set point for a biological thermostat
    30. 30. Figure 40.16

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