Chapter 16

1. Chapter 16 Tissues, Organs, and Organ Systems Organ Donation

2. 16.1 Tissues Tissues = group of similar cell types that perform a common function. Four basic types of tissue: • Epithelial • Connective • Muscle • Nervous

3. 16.1 Tissues - Epithelial Tissue (a) Examples of organs lined with epithelialtissue: (b) Epithelial cells in skin Heart and blood vessels Epidermis Respiratory tract Digestive tract Urogenital tract (c) Epithelial cells liningthe small intestine Epithelium is tightly packed sheets of cells • cover organs and outer surfaces • line insides of hollow organs, vessels, and body cavities. Figure 16.1

4. 16.1 Tissues - Epithelial Tissue Epithelia are polar • anchored on one surface, but free on another • The free side is typically exposed to the environment or body fluids • Can be single layer or many layers thick • Function in protection, secretion, and absorption • Epithelial cells are continuously sloughing off and are replaced by cell division

5. 16.1 Tissues - Connective Tissue Connective Tissue • Loosely organized and composed of cells embedded in a matrix • Cells • Blood cells, adipocytes, fibroblasts, chondrocytes, osteocytes • Matrix is composed of two things • Ground substance • Liquid, gel-like, rubbery or solid • Fibers • Collagen, elastin, reticular fibers

6. 16.1 Tissues - Connective Tissue Connective Tissue • Usually binds organs or tissues to one another • Six different types: • Loose connective tissue • Adipose tissue • Blood • Fibrous connective tissue • Cartilage • Bone

7. 16.1 Tissues - Connective Tissue Loose Connective Tissue • Most widespread tissue in animal body • Matrix composed of collagen and elastin fibers • It is called “loose” because fibers are loosely woven together • Binds epithelia to tissues, pads skin, and holds organs in place Figure 16.2a

8. 16.1 Tissues - Connective Tissue Adipose Tissue • AKA Fat • Primarily adipose cells; small amount of matrix • Functions • Used for storage of energy (fat) • Insulation • Padding for organs Figure 16.2b

9. 16.1 Tissues - Connective Tissue (c) Blood Platelet Redblood cell Plasma Whiteblood cell Blood • Cellular component • red blood cells, white blood cells and platelets • Matrix is the plasma • Functions include carrying oxygen and nutrients; fighting infection Figure 16.2c

10. 16.1 Tissues - Connective Tissue Fibrous Connective Tissue • Forms tendons and ligaments • Matrix is collagen fibers running in parallel (d) Fibrous connective tissue (tendon) Fibroblastcell Parallelcollagenfibers Figure 16.2d

11. 16.1 Tissues - Connective Tissue (e) Cartilage(at the end of a bone) Chondro-cytes Matrix Matrix Cartilage • Chondrocytes • Secrete rubbery matrix, collagen and elastin • Cartilage cushions joints, forms support for ears and nose • Not vascularized, so takes a long time to heal if injured Figure 16.2e

12. 16.1 Tissues - Connective Tissue (f) Bone Centralcanal Matrix Osteocytes Bone • Rigid connective tissue • Osteocytes • secrete matrix of collagen fibers and calcium salts • Bone marrow produces blood cells • Body can make use of calcium from bones if dietary levels are too low Figure 16.2f

13. 16.1 Tissues - Muscle Tissue Muscle is contractile tissue • Long, thin cylindrical cells called muscle fibers • Two proteins – actin and myosin – interact to cause contraction of muscle fibers • Three types of muscle: • Skeletal • Cardiac • Smooth

14. 16.1 Tissues - Muscle Tissue (a) Skeletal muscle (biceps) Muscle fiber Nucleus Skeletal Muscle • Usually attached to bone • Produces all voluntary movements • Striated • Long, thin, cylindrical shape Figure 16.3a

15. 16.1 Tissues - Muscle Tissue (b) Cardiac muscle (heart) Nucleus Muscle fiber Cardiac Muscle • Only found inheart tissue • Striated • involuntary, undergoes rhythmic contractions to produce heartbeat • Branched, interlocking cells propagate signal to contract almost simultaneously Figure 16.3b

16. 16.1 Tissues - Muscle Tissue (c) Smooth muscle (intestine) Muscle fiber Nucleus Smooth Muscle • Not striated • Spindle-shaped cells • Musculature of organs, blood vessels, digestive tract • Involuntary • Contracts more slowly and for longer than skeletal muscle Figure 16.3c

17. 16.1 Tissues - Nervous Tissue Nervous Tissue • Neurons conduct electrical signals • Primary cells of the brain and spinal cord • Main function of neurons is to: • Sense stimuli • Process stimuli • Transmit signals • Most cells of nervous system do not undergo cell division

18. 16.1 Tissues - Tissue Donation Brain death and Tissue Donation • Injuries from motor vehicle accidents, burst blood vessels, and drowning are common causes of brain death • Once dead, brain cells cannot recover • Tissues can be harvested to help others • > One person’s tissues can improve the lives of as many as 50 people.

19. 16.2 Organs and Organ Systems Muscle cell Muscle tissue Circulatory system Heart organ Organism • Organs are composed of two or more tissue types • Organs that act together form an organ system • All the organ systems of a body form an organism Figure 16.5

20. 16.2 Organs and Organ Systems 12 Organ Systems Figure 16.8

21. 16.2 Organs and Organ Systems – The Liver as a Model Organ • The liver sits below the diaphragm • comprised of four lobes • associated with the gall bladder. Figure 16.6

22. 16.2 Organs and Organ SystemsThe Liver as a Model Organ • The liver is an important component of the digestive and the circulatory system • As part of the circulatory system, the liver: • Synthesizes blood clotting factors • Detoxifies • Regulates blood volume • Destroys old red blood cells • As part of the digestive system, the liver: • Produces bile • Metabolizes and stores nutrients

23. 16.2 Organs and Organ Systems Liver Structure • Epithelia • Hepatocytes • Lining blood vessels • Lining bile ducts • Connective Tissue • Loose connective tissue • Kupffer cells

24. 16.2 Organs and Organ Systems - The Liver as a Model Organ • Liver transplants can be made from living donors or from brain dead ones • Unlike many organs, liver can regenerate itself • Portion can be taken from living donor and implanted in patient • Liver in donor and patient will regrow to normal size

25. 16.2 Organs and Organ SystemsThe Digestive System Mouth •Teeth reduce the size of food, increasing surface area available for digestion by enzymes. • Amylase enzymes in saliva start breaking down carbohydrates. Figure 16.8

26. 16.2 Organs and Organ SystemsThe Digestive System Esophagus •The esophagus transports food to stomach by rhythmic waves of muscle contractions called peristalsis. Figure 16.8

27. 16.2 Organs and Organ SystemsThe Digestive System Stomach • HCl starts breaking down foods. •The enzyme pepsin breaks down proteins. • Mucous prevents gastric juices from digesting stomach. • Pyloric sphincter regulates movement offood from stomach tosmall intestine. Figure 16.8

28. 16.2 Organs and Organ SystemsThe Digestive System Small intestine •Most digestion of carbohydrates, proteins,and fats occurs here. • Nutrients are absorbed into the bloodstream. Large intestine •Water is reabsorbed Figure 16.8

29. 16.2 Organs and Organ Systems - The Digestive System One villus Micrograph Small intestine Villus Lumen Bloodcapillaries Mucosal folds Microvilli Nutrients in small intestine Venule Arteriole Lymphaticvessel • Villi and microvilli increase the surface area of the intestines to allow nutrient absorption Figure 16.9

30. 16.2 Organs and Organ SystemsThe Digestive System Accessory Organs Liver •Produces bile which aids absorption of fats Gall bladder •Stores bile and empties into small intestine Figure 16.8

31. 16.2 Organs and Organ SystemsThe Digestive System Accessory Organs Pancreas •Produces LOTS of digestive enzymes • Produces a bufferthat neutralizes stomach acid • Enzymes & buffer are released into small intestine Figure 16.8

32. 16.2 Organs and Organ Systems An organ system consists of many organs working together • Failure of one organ may compromise the entire system • Intestine transplants and pancreatic transplants are becoming more common • Gall bladder and stomach transplants are rarely done • Organ failure can also disrupt multiple systems

33. 16.2 Organs and Organ Systems PLAY Animation—The Digestive System

34. 16.2 Organs and Organ Systems Evolution of the Digestive System • Paramecia use digestive food vacuoles • Hydra have an extracellular digestive sac • Earthworms have alimentary canal • Allows for ‘assembly line’ like specialization Figure 16.9

35. Homeostasis Homeostasis • a dynamic state of equilibrium in which internal conditions remain relative stable (Steady State) • homeostasis regulates conditions in the internal environment • A homeostatic control system has • a receptor • a control center • a set point • an effector

36. Response No heat produced Heater turned off Room temperature decreases Set point Too hot Set point Set point Too cold Control center: thermostat LE 40-11 Room temperature increases Heater turned on Response Heat produced

37. 16.3 Regulating the Internal Environment Homeostasis (a) If blood glucoselevel rises... Liver converts glucoseto glycogen. Glycogen Glucose Pancreassecretes insulin. Liver Blood glucoselevel falls. HomeostasisNormal blood glucose level (b) If blood glucoselevel falls... Glucose levels rise. Glucose Glycogen Liver Pancreassecretes glucagon. Liver breaks down glycogeninto glucose and releasesglucose into bloodstream. • Negative feedback is when the outcome of a process inhibits that process. Figure 16.11

38. 16.3 Regulating the Internal Environment Homeostasis • Positive feedback occurs when the outcome of a process increases or intensifies that process. • During childbirth, hormones cause muscles of uterus to contract • Uterine contractions cause even more hormones to be released, which intensify the contractions • > In animals, regulation is usually by negative feedback because positive feedback often results in amplification – away from homeostasis

39. 16.3 Regulating the Internal Environment – Organ Donation • The best candidates to donate organs are those who have died of brain injury. • In cardiac death, organs deteriorate due to lack of oxygen, and thus are less suitable for transplant. • Thousands of lives are saved each year through organ donation. • The decision to become a donor now can save families from making difficult decisions later.