CELLS & TISSUES Chapter 3 – Pgs. 59-70

1. CELLS & TISSUESChapter 3 – Pgs. 59-70 • Tissue – group of cells working together to perform a specific function • Histology – the study of tissues • Four groups of tissues: • Epithelial – Table 3-6 • Connective – Table 3-7 • Muscle – Table 3-8 • Nerve – Table 3-8

4. Epithelial • Found of the surfaces as covering (skin) or on inner surfaces as lining (digestive tract); many types are capable of secretion (sweat, saliva, digestive enzymes) • Epithelial cells are classified according to shape and arrangement of cells – fig. 3-7

5. Shapesquamous – flat, scale likecuboidal – cube shapedcolumnar – tall and narrow

6. Arrangementsimple – single layer of cells of the same shapestratified - many layers of cells of the same shapetransitional – several layers of cells with different shapes

7. Simple Squamous – important in the exchange of materials or for absorption; found in capillaries, alveoli (air sacs) – Fig. 3-8

9. Stratified squamous epithelium – Fig. 3-9 • makes up epidermis of skin where surface cells are dead (keratinized) • lining of mouth, esophagus, and vagina where surface cells are alive (non-keratinized) • function in protection and barrier for microorganisms

10. Keratinized stratified squamous epithelium

11. Non keratinized stratified squamous epithelium

12. Simple Columnar Epithelial – Fig. 3-10 • Single layer of cells taller than wide • linings of stomach, intestines, and respiratory tract • specialized cells called goblet cells secrete mucus • regular cells specialize in absorption

14. Simple Cuboidal (glandular epithelium) – Fig. 3-8, 3-12 • single layer of cube-shaped cells • function in secretory activity • glands; cluster or groups of secretory cells • exocrine – release secretions into ducts (ex. Salivary glands) • endocrine – release secretions directly into bloodstream (ex. Thyroid gland)

16. Stratified Transitional Epithelium – Fig. 3-11 • surface cells change shape from cuboidal to squamous • found in areas exposed to stress and need to be able to stretch (ex. Urinary bladder)

18. Pseudostratified epithelium (ciliated) • columnar cells that have cilia and look as if there are two cell layers • cilia sweeps mucus trapped dust and bacteria protecting lungs • lines nasal cavities, trachea, and bronchial tubes • also lines fallopian tubes (oviducts) and sweeps ovum from ovary to uterus

20. Connective Tissue • Most abundant tissue type, most varied, common to all is the presence of a matrix in addition to cells – matrix is a structural network or solution of non-living intracellular material (ex. Blood matrix is plasma, bone matrix is calcium salts)

21. Aereola (loose connective tissue) most widely distributed connective tissue •  cells are called fibroblasts which produce protein fibers (collagen and elastin) • Protein fibers and tissue fluid makeup matrix • found beneath epithelial tissues and body systems that have an opening to the environment for protection against microorganisms • functions as “glue” that gives form to internal organs and protection

23. Adipose – Fig. 3-13 • cells are called adipocytes • matrix consists of tissue fluid and some collagen fibers • function – storage of lipids/cushion for organs

25. Fibrous Connective Tissue – Fig. 3-14 • consists mainly of parallel collagen fibers • strong but flexible • makes up tendons and ligaments • tendon – connects muscle to bone • ligament – connects bone to bone • relatively poor blood supply, slow to heal

27. Bone – Fig. 3-15 • cells are called osteocytes • matrix is made of calcium salts and collagen – strong, hard, not flexible • osteocytes, matrix, and blood vessels are arranged in Haversian system • functions – calcium storage, support body, protect internal organs

29. Cartilage – Fig. 3-16 • cells called chondrocytes • found on surfaces of joints to prevent friction • found in ear, tip of nose, wall of trachea, and in between vertebrae • function – prevent friction, absorbs shock, permits movement • no capillaries, gets nourishment through diffusion from surrounding tissues

31. Blood – Fig. 3-17 • Matrix is blood plasma • plasma contains dissolved salts, nutrients, and waste products • function of plasma – transportation of material around the body • cells of blood • red blood cells carry oxygen • white blood cells destroy pathogens – principle component of the immune system • platelets – prevent blood loss through clotting

32. Red blood cell White Blood cell Platelet

33. Hemopoietic Tissue • found in red marrow cavities of bone, spleen, tonsils, and lymph nodes • function in formation of blood cells – important in defense against disease • This tissue is a complex mixture of different cell types and a rich lattice

35. Replacement of bone marrow fat with dark red hemopoietic tissue

36. Muscle – specialized for contraction, when muscles contract they shorten and bring about some type of movement

37. Skeletal Muscle (striated or voluntary muscle) – Fig. 3-18 • cylindrical, have several nuclei/cell • appear striated b/c of precise arrangement of contracting proteins in cells • muscles are attached to bones and move skeleton • voluntary in movement, respond to nerve stimuli from brain

39. Smooth Muscle (visceral or involuntary) – Fig. 3-20 • long, narrow, single nuclei/cell, no striation • involuntary • form walls of blood vessels, and organs such as stomach and intestines • help regulate diameter of blood vessels and propels food down digestive tract

41. Cardiac Muscle (myocardium) – Fig. 3-19 • branched, interlocking muscle, faintly striated, 1 nuclei/cell • form walls of chambers of the heart • function – pump blood, maintain blood pressure • contract by themselves and therefore maintain “one” beat • nerve impulses from nervous system function to increase or decrease beat as dictated by certain situations

43. Nerve Tissue – Fig. 3-21 • cells are called neurons, supporting cells are neuroglia • function – transmit electrochemical impulses • structure of neuron • cell body – contains nucleus • axon – carries impulses away from cell body • dendrite – carries impulses toward cell body • each neuron has several dendrites that branch in different direction • impulses are transmitted from one neuron to another at the synaptic cleft by chemical messengers called neurotransmitters • make up brain, spinal cord, and nerves • function – sensation, movements, regulation of body functions, organization of information for learning and memory