The Animal Body and Principles of Regulation

1. The Animal Body andPrinciples of Regulation Chapter 43

2. Organization of Vertebrate Body • There are four levels of organization: • Cells • Tissues • Organs • Organ systems

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

4. Organization of Vertebrate Body • Organs are combinations of different tissues that form a structural and functional unit • Organ systems are groups of organs that cooperate to perform the major activities of the body • The vertebrate body contains 11 principal organ systems

5. Organization of Vertebrate Body examples

6. Organization of Vertebrate Body • The 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 • Inside the body are two identifiable cavities

7. Organization of Vertebrate Body • Dorsal body cavity - Within skull and vertebrae • Ventral body cavity - Bounded by the rib cage and vertebral column and divided by the diaphragm into: • Thoracic cavity - heart and lungs • Pericardial cavity: around the heart • Pleural cavity: around the lungs • Abdominopelvic cavity - most organs • Peritoneal cavity - coelomic space around organs

8. Organization of Vertebrate Body

9. Organization of Vertebrate Body

10. Organization of Vertebrate Body

11. Organization of Vertebrate Body

12. 1. 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 • Epithelia possess remarkable regenerative powers replacing cells throughout life

13. 1. Epithelial Tissue • Epithelial tissues attach to underlying connective tissues by a fibrous membrane • Basal surface - Secured side • Apical surface - Free side • Therefore, epithelia have inherent polarity, which is important for their function

14. 1. Epithelial Tissue • Two general classes • Simple - one layer thick • Stratified - several layers thick • Subdivided by shape into: • Squamous cells - flat • Cuboidal cells - cube-shaped • Columnar cells - cylinder-shaped

15. Simple Epithelium • Simple squamous epithelium • Lines lungs and blood capillaries • 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 that secrete mucus

16. Simple Epithelium • Glands of vertebrates form from invaginated epithelia • Exocrine glands • connected to epithelium by a duct • e.g. sweat, sebaceous and salivary glands • Endocrine glands • ductless • secretions (=hormones) enter blood

17. Stratified Epithelium • Named according to the features of their apical (free side) cell layers • Epidermis is a stratified squamous epithelium • Characterized as a keratinized epithelium • Contains water-resistant keratin • Note: Lips are covered with nonkeratinized, stratified squamous epithelium

18. 2. Connective Tissues • Derive from embryonic mesoderm • Divided into two major classes • Connective tissue proper • Loose or dense • Special connective tissue • Cartilage, bone and blood • All have abundant extracellular material called the matrix • Protein fibers plus ground substance • Ground substance is fluid material containing an array of proteins and polysaccharides

19. Connective Tissue Proper • Fibroblasts produce and secrete extracellular matrix • Loose connective tissue • Cells scattered within a matrix that contains large amounts of ground substance • Strengthened by protein fibers such as: • Collagen – Supports tissue • Elastin – Makes tissue elastic

20. Connective Tissue Proper • Adipose cells (fat cells) also occur in loose connective tissue • Develop in large groups in certain areas, forming adipose tissue

21. Connective Tissue Proper • Dense connective tissue • Contains less ground substance and more collagen 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 & bone

22. Special Connective Tissue • Cartilage • Ground substance made from characteristic glycoprotein, called chondroitin, and collagen fibers in long, parallel arrays • Flexible with great tensile strength • Found in joint surfaces and other locations • Chondrocytes (cartilage cells) live within lacunae (spaces) in the ground substance

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

24. 3. 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 smooth and cardiac is involuntary

25. 3. Muscle Tissue • Smooth muscles are found in walls of blood vessels and visceral organs • Cells are mono-nucleated • Skeletal muscles are usually attached to bone by tendons, so muscle contraction causes bones to move • Muscle fibers (cells) are multi-nucleated • Contract by means of myofibrils, that contain ordered actin and myosin filaments

26. 3. Muscle Tissue • Cardiac muscle is composed of smaller, interconnected cells • Each cell has a single nucleus • Interconnections appear as dark lines called intercalated disks • Enable cardiac muscle cells to form a single functioning unit

27. 4. Nerve Tissue • Cells include neurons and their supporting cells called 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

28. 4. 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, known as nodes of Ranvier, are involved in acceleration of impulses

29. 4. 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 body

30. Overview of Organ Systems • Communication and integration • Three organ systems detect external stimuli and coordinate the body’s responses • Nervous, sensory and endocrine systems

31. Overview of Organ Systems • Support and movement • The musculoskeletalsystem consists of the interrelated skeletal and muscular organ systems

32. Overview of Organ Systems • Regulation and maintenance • Four organ systems regulate and maintain the body’s chemistry • Digestive, circulatory, respiratory and urinary systems

33. Overview of Organ Systems • Defense • The body defends itself with two organ systems: integumentary and immune

34. Overview of Organ Systems • Reproduction and development • The biological continuity of vertebrates is the province of the reproductive system • In females, the system also nurtures the developing embryo and fetus

35. Homeostasis • 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

36. Homeostasis

37. Homeostasis • To maintain internal constancy, the vertebrate body uses 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

38. Homeostasis • If a deviation is detected, a message is sent to an effector (muscle or gland) • Increase or decrease in activity brings internal conditions back to set point • Negative feedback to the sensor terminates the response

39. Homeostasis

40. Homeostasis • Humans have set points for body temperature, blood glucose concentrations, electrolyte (ion) concentration, tendon tension, etc. • We are endothermic: can maintain a relatively constant body temperature (37oC or 98.6oF) • Changes in body temperature are detected by the hypothalamus in the brain

41. Homeostasis • Negative feedback mechanisms often oppose each other to produce finer degree of control • Many internal factors are controlled by antagonistic effectors • Have “push-pull” action • Increasing activity of one effector is accompanied by decrease in the other

42. Homeostasis • 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

43. Homeostasis room body

44. Homeostasis • In a few cases, the body uses positive feedback mechanisms to enhance a change • These do not in themselves maintain homeostasis • However, they are generally part of some larger mechanism that does! • Examples: • Blood clotting • Contraction of uterus during childbirth

45. Homeostasis