Lecture Outline - Chapter 11

11.1. Types of Tissues (p. 186)

1. Tissues are categorized into four major types: epithelial, connective, muscular, and nervous tissues.
2. Cancers are classified according to the tissue from which they arise:
   • a. Carcinomas are cancers of epithelial tissues.
   • b. Sarcomas are cancers of muscle or connective tissues, especially bone and cartilage.
   • c. Leukemias are cancers of the blood.
   • d. Lymphomas are cancers of reticular connective tissue.
   • e. Cancers are more likely in tissue with higher rates of cell division.
3. Epithelial Tissues
   • a. Epithelium consists of tightly packed cells forming a continuous sheet over the body surface and internal cavities.
   • b. Epithelium functions to prevent tissues from drying out and protect from injury.
   • c. Functions of internal epithelium vary:
     • i. Digestive tract epithelium secretes mucus.
     • ii. Lung epithelium has cilia that brush up impurities.
     • iii. Intestinal epithelium absorbs molecules with microvilli.
   • d. Types of Epithelial Tissue
     • i. Simple squamous epithelium is flattened cells.
     • ii. Cuboidal epithelium has cube-shaped cells.
     • iii. Columnar epithelium has rectangle-shaped pillar-like cells.
     • iv. Pseudostratified appears to be layered but true layers do not exist because each cell touches a basement membrane that joins epithelium to underlying connective tissue.
   • e. Glands that secrete their products into ducts are exocrine glands; those that secrete directly into bloodstream are called endocrine glands. A gland may be a single epithelial cell such as a goblet cell in digestive tract that produces mucus.
   • f. Junctions (Fig. 11.2) (p. 188)
     • i. Tight junctions form an impermeable barrier because adjacent membrane proteins join, producing a zipperlike fastening.
     • ii. Desmosomes are adhesion junctions between two cells, held together by intercellular filaments attached to buttonlike thickenings.
     • iii. Gap junctions are communication junctions that form when two identical plasma membrane channels join; allowing small molecules to pass between the cells.
4. Connective Tissues (p. 188)
   • a. Functions: provide support, protect, insulate, store fat, and produce blood cells.
   • b. Connective tissue cells are usually widely separated by a noncellular matrix that may have white collagen fibers for strength and/or elastic yellow fibers containing elastin.
   • c. Reticular fibers are very thin and highly branched.
   • d. Types of Connective Tissues
     • i. Loose Connective Tissue (Fig. 11.3)
       - binds structures together.
       - are fibroblast cells.
       - are widely separated.
       - matrix contains many collagen and elastic fibers.
       - common under skin.

       ii. Adipose Tissue (Fig. 11.13b)

       - type of loose connective tissue.

       - the fibroblasts enlarge and store fat for insulation/energy.

       - intercellular matrix is reduced.

       iii. Reticular cells or lymphoid tissue contain only fibers; occur in lymph nodes, spleen, bone marrow.

       iv. Fibrous Connective Tissue

       - found in tendons, which bind muscle to bone and ligaments, which connect bone to bone.

       - contains large numbers of collagenous fibers closely packed together.

       - functions to bind organs together.

       - poor blood supply means injuries take long to heal.
   • e. Cartilage
     • i. Cells lie in chambers called lacunae separated by a flexible matrix.
     • ii. Lacking a direct blood supply, cartilage heals very slowly.
     • iii. Hyaline cartilage contains fine collagen fibers and the matrix has a white translucent appearance; functions to support and protect; located at ends of long bones, rings in trachea, fetal skeleton. (Fig. 11.3c)
     • iv. Elastic cartilage: has more elastic fibers and therefore is more flexible.
     • v. Fibrocartilage has many collagenous fibers within the matrix to withstand tension and pressure; for example, between vertebrae and knee joints.
   • f. Bone
     • i. Extremely hard matrix is due to deposition of calcium salts around protein fibers.
     • ii. Compact bone is formed by osteocytes located in lacunae arranged in concentric circles around Haversian canals which contains blood vessels and nerves; minute canals called canaliculi connect osteocytes together. (Fig. 11.3d)
     • iii. Spongy bone is found at ends of long bones; it contains numerous bony bars and plates separated by spaces filled with marrow.
   • g. Blood (Fig. 11.4)
     • i. Whole blood can be separated into plasma (55%) and a cell component.
     • ii. Plasma contains a variety of inorganic and organic substances dissolved in water. (Table 11.1)
     • iii. Blood solids include red blood cells (erythrocytes), white blood cells (leucocytes), and blood platelets (thrombocytes).
     • iv. Human red blood cells:
       - lack a nucleus.
       - are biconcave disk-shaped cells.
       - are manufactured in red bone marrow.
       - contain the red pigment hemoglobin.
       - hemoglobin associates with oxygen.

       v. White blood cells:

       - have a nucleus.

       - some engulf microbes.

       - some produce antibodies.

       vi. Platelets:

       - are fragments rather than whole cells.

       - begin the clotting process when a blood vessel is damaged.

       vii. Liquid matrix of blood makes it different from other connective tissues; some classify blood as distinct vascular tissue.
5. Muscular Tissue
   • a. Muscle is contractile tissue.
   • b. Muscle cells are called muscle fibers.
   • c. Muscle fibers contain actin and myosin filaments; their action accounts for movement.
   • d. Types of vertebrate muscles:
     • i. Skeletal muscle: (Fig. 11.5a)
       - has striations.
       - cells are multinucleate.
       - cell nuclei are located peripherally.
       - responds to voluntary control.
       - are attached to bones of the skeleton.

       ii. Smooth muscle: (Fig. 11.5b)

       - lacks striations.

       - cells are spindle-shaped with irregular nuclei.

       - is involuntary.

       - is found in internal organs; for instance intestinal peristalsis and blood vessel constriction. - contracts slower but for a longer time than skeletal muscle.

       iii. Cardiac muscle: (Fig. 11.5c)

       - found only in heart.

       - has striations and branching cells.

       - mostly involuntary.

       - cells are bound end-to-end at intercalated disks.

       - cells have single central nucleus.
6. Nervous Tissue
   • a. The neuron conducts nerve impulses to and from brain and spinal cord.
   • b. The cell body contains nucleus of a neuron.
   • c. Dendrites conduct impulses to cell body.
   • d. The axon conducts impulses away from cell body.
   • e. Dendrites and axons are termed nerve fibers and many are bound together to make up a nerve.
   • f. Neuroglial cells provide support, protection, and nourishment to neurons.

1. Functions to cover the body, protecting underlying parts from trauma, microbes, and water loss; helps to regulate body temperature, senses our surroundings, and communicates by touch.
2. Skin Layers
   • a. Epidermis:
     • i. is outer, thinner layer of the skin.
     • ii. is made up of stratified squamous epithelium, which is continually produced by bottom basal layer.
     • iii. Dead cells at top contain keratin, a waterproof protein.
     • iv. Dandruff occurs when rate of keratinization is 2- 3 times higher.
     • v. Melanocytes produce melanin, the pigment responsible for skin color that protects skin from ultraviolet radiation in sunlight.
   • b. Dermis:
     • i. Consists of a layer of fibrous connective tissue thicker than epidermis.
     • ii. Aging involves decrease in collagen and elastic fibers.
     • iii. Hair
       - Root of hair resides in the hair follicle; produces epidermal cells that harden and die.
       - Oil (sebaceous) glands empty into each hair follicle and secrete sebum used to lubricate the hair and skin.
       - Arrector pili muscle is attached to the hair and causes goose bumps to form.
       - Sweat (sudoriferous) glands are numerous in humans; used to control body temperature.
       - Sense organs in skin include receptors used for touch, pressure, pain, etc.
       - Blood vessels expand (blush) and contract (turn pale).
   • c. Subcutaneous layer:
     - lies below dermis.
     - composed of loose connective tissue and adipose which helps to insulate and give the body a rounded appearance.

11.3. Studying Organ Systems (p. 195)

1. Organ systems studied in this text are listed in Table 11.2.
2. Skeleton provides surface area for attachment of muscles; musculo-skeletal system makes up most body weight.
3. Nervous system is brain located in dorsal cavity and spine in vertebral canal. (Fig. 11.8)
4. Coelom is large ventral cavity divided by diaphragm into:
   • a. thorax (chest) which includes heart and lungs.
   • b. abdominal cavity which includes digestive, excretory, and reproductive systems.
5. Body Membranes
   • a. Organ membranes are epithelium overlying loose connective tissue; mucous membrane lines respiratory and digestive systems and secretes mucus.
   • b. Serous membranes line enclosed cavities in the heart, lungs, and kidneys and secrete a watery lubricating fluid.

1. Homeostasis holds the internal environment relatively constant, regardless of the conditions in the external environment.
2. Examples of Homeostasis
   • a. Blood glucose concentration remains at 0.1%.
   • b. Blood pH holds near 7.4.
   • c. Blood pressure in brachial artery is near 120/80.
   • d. Body temperature averages near 37oC.
3. Internal environment is maintained by the tissue fluid, which bathes all the tissues of the body. Tissue fluid is refreshed when oxygen and nutrients exit the blood and wastes enter the blood. (Fig. 11.9)
4. Examples of Balanced Systems
   • a. Blood pressure aids movement of water out of capillaries; osmotic pressure moves water into capillaries.
   • b. Digestive system ingests and digests food; body cells constantly remove nutrients.
   • c. Respiration adds oxygen and removes carbon dioxide; body tissues do reverse.
   • d. The liver stores excess glucose as glycogen; breaks down glycogen when glucose levels drop--this is regulated by insulin.
   • e. The kidneys excrete nitrogenous wastes formed by liver and regulate blood volume, salt balance, and pH of blood.
   • f. These and other complex system relationships demonstrate how mechanisms of homeostasis maintain a constant internal environment.
5. Nervous and Endocrine Systems
   • a. Regulation of homeostasis is achieved by hormones; for instance pancreatic insulin production drops when glucose levels fall.
   • b. Negative feedback is a control mechanism that self-regulates many processes; for example, the pituitary gland produces a hormone to stimulate the thyroid to secrete; when the thyroid hormone level rises to a certain level, the pituitary gland stops production of the hormone.
   • c. Feedback systems are similar to the thermostat that maintains an even house temperature.
   • d. Effectors bring about a response that negates the original conditions that stimulated the receptor. (Fig. 11.10)
   • e. Ultimately the nervous and endocrine systems control homeostasis.
6. Controlling Body Temperature
   • a. A receptor in hypothalamus senses when temperature of blood falls below normal.
   • b. A regulatory center in hypothalamus sends nerve impulses to blood vessels of skin causing them to contract and arrector pili muscles to become erect. (Fig. 11.11)
   • c. If temperature continues to fall, the regulator center sends impulses to skeletal muscles to initiate shivering to generate heat.
   • d. Higher body temperatures trigger regulator center to send signals to dilate skin blood vessels and bring more blood to the surface where heat is lost.