1. Chapter 42 The Animal Body and Principles of Regulation

2. Organization of Vertebrate Body There are four levels of organization 1.Cells 2.Tissues 3.Organs 4.Organ systems Bodies of vertebrates are composed of different cell types –Humans have 210 2

3. Organization of Vertebrate Body Tissues Groups of cells that are similar in structure and function 3 fundamental embryonic tissues are called germ layers Endoderm, mesoderm, and ectoderm In adult vertebrates, there are four primary tissues Epithelial, connective, muscle, and nerve 3

4. Organization of Vertebrate Body Organs –Combinations of different tissues that form a structural and functional unit Organ systems –Groups of organs that cooperate to perform the major activities of the body –Vertebrate body contains 11 principal organ systems 4

5. Organization of Vertebrate Body General body plan of all vertebrates is essentially a tube within a tube –Inner tube – digestive tract –Outer tube – main vertebrate body Supported by a skeleton –Outermost layer – skin and its accessories 5

6. 6 Organization of Vertebrate Body 2 main body cavities –Dorsal body cavity Forms within skull and vertebrae –Ventral body cavity Bounded by the rib cage and vertebral column Divided by the diaphragm into Thoracic cavity – heart and lungs Abdominopelvic cavity – most organs

7. Epithelial Tissue An epithelial membrane, or epithelium, covers every surface of the vertebrate body Can come from any of the 3 germ layers Some epithelia change into glands Cells of epithelia are tightly bound together –Provide a protective barrier 7

8. Epithelial Tissue Epithelia possess remarkable regenerative powers replacing cells throughout life Epithelial tissues attach to underlying connective tissues by a fibrous membrane –Basal surface – secured side –Apical surface – free side –Inherent polarity important for their function 8

9. Epithelial Tissue Two general classes Simple – one layer thick Stratified – several layers thick Each class subdivided into Squamous cells – flat Cuboidal cells – about as wide as tall Columnar cells – taller than they are wide 9

10. Simple Epithelium Simple squamous epithelium –Lines lungs and blood capillaries –Delicate nature permits diffusion Simple cuboidal epithelium –Lines kidney tubules and several glands Simple columnar epithelium –Lines airways of respiratory tract and most of the gastrointestinal tract –Contains goblet cells – secrete mucus 10

11. Lines capillaries Lines aveoli in lungs

12. This is a cross-section of a kidney tubule 12

13. Cross-section of small intestine 13

14. Simple Epithelium Exocrine glands Connected to epithelium by a duct Sweat, sebaceous, and salivary glands Endocrine glands Ductless – lost duct during development Secretions (hormones) enter blood 14 http://commonsensehealth.com/wp-content/uploads/2013/08/endocrineglands.gif

15. Stratified Epithelium 2 to several layers thick Named according to the features of their apical cell layers Epidermis is a stratified squamous epithelium –Terrestrial vertebrates have a keratinized epithelium Contains water-resistant keratin –Lips are covered with nonkeratinized, stratified squamous epithelium 15

16. Connective Tissues Derive from embryonic mesoderm All have abundant extracellular material called the matrix –Protein fibers plus ground substance 16

17. Divided into two major classes: Connective tissue proper Loose Fibroblasts, some immune cells (mast cells and macrophages), adipose (fat) Supports organs Dense Stronger, more tightly packed collagen Tendons, sheath around muscles Special connective tissue Cartilage Bone blood 17

18. Connective Tissue Proper Fibroblasts produce and secrete extracellular matrix Loose connective tissue –Cells scattered within a matrix that contains a large amount of ground substance –Strengthened by protein fibers Collagen – supports tissue Elastin – makes tissue elastic Reticulin – helps support the network of collagen 18

19. Connective Tissue Proper Adipose cells (fat cells) also occur in loose connective tissue –Develop in large groups in certain areas, forming adipose tissue 19 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 200 µm © Biophoto Associates/ Photo Researchers, Inc.

20. Connective Tissue Proper Dense connective tissue –Contains less ground substance than loose connective tissue –Dense regular connective tissue Collagen fibers line up in parallel Makes up tendons and ligaments –Dense irregular connective tissue Collagen fibers have different orientations Covers kidney, muscles, nerves, and bone 20

21. Special Connective Tissue Cartilage Firm and flexible tissue that does not stretch Great tensile strength Found in joint surfaces and other locations Chondrocytes (cartilage cells) live within lacunae (spaces) in the ground substance 21

22. Special Connective Tissue Bone –Osteocytes (bone cells) remain alive in a matrix hardened with calcium phosphate –Communicate through canaliculi Blood –Extracellular material is the fluid plasma –Erythrocytes – red blood cells –Leukocytes – white blood cells –Thrombocytes – platelets 22

23. Muscle Tissue Muscles are the motors of vertebrate bodies Three kinds: smooth, skeletal, and cardiac Skeletal and cardiac muscles are also known as striated muscles Skeletal muscle is under voluntary control, whereas contraction of the other two is involuntary 23

24. Muscle Tissue Smooth muscle –Found in walls of blood vessels and visceral organs –Contain a single nucleus Skeletal muscle –Usually attached to bone by tendons, so muscle contraction causes bones to move –Muscle fibers (cells) are multinucleated –Contract by means of myofibrils, which contain ordered actin and myosin filaments 24

25. Muscle Tissue Cardiac muscle –Composed of smaller, interconnected cells –Each with a single nucleus –Interconnections appear as dark lines called intercalated disks Gap junctions link adjacent cells –Enable cardiac muscle cells to form a single functioning unit 25

26. Nerve Tissue Cells include neurons and their supporting cells (neuroglia) Most neurons consist of three parts –Cell body – contains the nucleus –Dendrites – highly branched extensions Conduct electrical impulses toward the cell body –Axon – single cytoplasmic extension Conducts impulses away from cell body 26

27. Nerve Tissue Neuroglia –Do not conduct electrical impulses –Support and insulate neurons and eliminate foreign materials in and around neurons –Associate with axon to form an insulating cover called the myelin sheath Gaps (nodes of Ranvier) are involved in acceleration of impulses 27

28. Nerve Tissue Nervous system is divided into –Central nervous system (CNS) Brain and spinal cord Integration and interpretation of input –Peripheral nervous system (PNS) Nerves and ganglia (collections of cell bodies) Communication of signal to and from the CNS to the rest of the body 28

29. Communication and integration Three organ systems detect external stimuli and coordinate the body’s responses: –Nervous, sensory, and endocrine systems Support and movement Muscle and skeletal systems Regulation and maintenance Four organ systems regulate and maintain the body’s chemistry: –Digestive, circulatory, respiratory, and urinary systems Defense The body defends itself –Integumentary and immune systems Reproduction and development Reproductive system In females, the system also nurtures the developing embryo and fetus 29 Overview of Organ Systems

30. As animals have evolved, specialization of body structures has increased For cells to function efficiently and interact properly, internal body conditions must be relatively constant The dynamic constancy of the internal environment is called homeostasis It is essential for life 30 Homeostasis

31. Negative feedback mechanisms Changing conditions are detected by sensors (cells or membrane receptors) Information is fed to an integrating center, also called comparator (brain, spinal cord, or endocrine gland) Compares conditions to a set point If conditions deviate too far from a set point, biochemical reactions are initiated to change conditions back toward the set point 31

32. Humans have set points for body temperature, blood glucose concentrations, electrolyte (ion) concentration, tendon tension, etc. Integrating center is often a particular region of the brain or spinal cord Effectors (muscles or glands) change conditions back toward the set point values 32 Homeostasis

33. Mammals and birds are endothermic –Maintain a relatively constant body temperature independent of the environmental temperature –Humans 37 o C or 98.6 o F –Changes in body temperature are detected by the hypothalamus in the brain Antagonistic effectors are involved in the control of body temperature If hypothalamus detects high temperature –Promotes heat dissipation via sweating and dilation of blood vessels in skin If hypothalamus detects low temperature –Promotes heat conservation via shivering and constriction of blood vessels in skin 33 Homeostasis

34. 34 Homeostasis

35. Positive feedback mechanisms –Enhance a change not as common as negative feedback mechanisms –These do not in themselves maintain homeostasis –Important components of some physiological mechanisms Blood clotting Contraction of uterus during childbirth 35 Homeostasis

36. Regulating Body Temperature Temperature is one of the most important aspects of the environment Some organisms have a body temperature that conforms to the environment Other organisms regulate their body temperature 36

37. Q 10 is a measure of temperature sensitivity –The rate of any chemical reaction is affected by temperature –The rate increases with increasing temperature –Every 10°C increase in temperature doubles the reaction rate up to a specific limiting temperature 37

38. Temperature determined by internal and external factors –Overall metabolic rate and body temperature are interrelated –Organisms must deal with external and internal factors that relate body heat, metabolism, and the environment 38 body heat = heat produced + heat transferred

39. Mechanisms of heat transfer Radiation - The transfer of heat by electromagnetic radiation Conduction - The direct transfer of heat between two objects. Energy is transferred from hotter objects to colder ones. Convection - Convection is the transfer of heat brought about by the movement of a gas or liquid. Evaporation - Heat of vaporization or the amount of energy needed to change them from a liquid to a gas phase 39

40. Ectotherms regulate temperature using behavior –Low metabolic rates –Regulate their temperature using behavior 40 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Flight Full-range movement of wings Warm up Shiver-like contraction of thorax muscles Preflight No wing movement 40 35 30 25 –101234 Time (min) Temperature (ºC) of thorax muscles

41. Endotherms create internal metabolic heat –Conservation or dissipation –Heat transfer is controlled by amount of blood flow to the surface of the animal Countercurrent exchange –Allows sustained high-energy activity –Tradeoff is the high metabolic rate 41

42. Body size and insulation –Changes in body mass have a large effect on metabolic rate –Smaller animals consume much more energy per unit body mass than larger animals –Summarized in the “mouse to elephant” curve Nonproportionality of metabolic rate versus size of mammals 42

43. Mammalian thermoregulation is controlled by the hypothalamus –Neurons in the hypothalamus detect the temperature change –Stimulation of the heat-losing center Peripheral blood vessel dilation Sweating –Stimulation of heat-promoting center Thermogenesis – shivering Constriction of blood peripheral blood vessels Epinephrine production by adrenal glands Anterior pituitary produces TSH 43

44. Why is shivering used to increase temperature? Remember cellular respiration? The conversion of energy found in glucose molecule into ATP Remember that with any energy transformation, some energy is lost as heat If you shiver, your body is forcing the muscles to go through more cellular respiration, therefore creating more heat 44

45. 45 Control of body temperature by the hypothalamus Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. () () Stimulus Sun Perturbing factor Snow and ice Perturbing factor Stimulus Sensor Hypothalamus Integrating Center Blood vessels dilate Glands release sweat Blood vessels constrict Response Body temperature rises Body temperature drops Thermoreceptors Negative feedback Negative feedback Body temperature rises Skeletal muscles contract, shiver Effector Body temperature falls