רקמות בגוף האדם רקמה – אוסף של תאים בעלי מבנה, צורה ותפקוד זהים.

Chapter 4 Tissues Definition: A group of cells and extracellular material that are related in structure and function The Four Basic Types: Epithelial Connective Tissue (CT) Muscle Nerve

Epithelium Covering and lining epithelium Glands (22.25) (4.1)

Epithelium Functions –Protection –Sensory reception –Secretion –Absorption –Ion transport –Filter –Transport through body (4.1)

Characteristics of Epithelium (4.1)

Classification of Epithelia (4.2a) –Simple –Stratified Apical layer Basal layer –Pseudostratified

Classification of Epithelia Shape of apical cells –Squamous –Cuboidal –Columnar –Note shape of nuclei (4.2b)

Simple Squamous Epithelium Diffusion, filtration, secretion Capillaries, alveoli (4.3a)

Locations: –Air sacs (alveoli) of lungs –Glomerular capsules of kidneys –Some kidney tubules –Lining of heart and all blood vessels Here it’s called the endothelium –Serous membranes –External lining of visceral organs –Here it’s called the mesothelium Simple Squamous Epithelium

Simple Cuboidal Epithelium Diffusion, secretion, absorption Kidney (4.3b)

Locations: –Liver –Pancreas Cross-Section of a kidney tubule Simple Cuboidal Epithelium

Functions: –Absorption Kidney tubules Liver –Secretion Kidney tubules Liver Pancreas Thyroid, salivary, and most other glands Cross-section of the thyroid gland Simple Cuboidal Epithelium

Simple Columnar Epithelium Absorption, secretion Digestive tract (4.3c)

Simple Columnar Epithelium Locations: –Inner lining of stomach, intestines, and rectum. –Inner lining of gallbladder –Inner lining of uterus and uterine tubes Simple columnar epithelium lining the lumen of the gallbladder.

Simple Columnar Epithelium Functions: –Absorption and secretion Columnar cells in small intestine have microvilli to increase the available surface area for the absorption of nutrients. –Movement of egg and embryo in uterine tube. Hence the presence of cilia.

Pseudostratified Columnar One layer of cells of differing heights Secretion Upper respiratory tract –With cilia (PSCC) (4.3d)

Stratified Squamous Protection against friction Skin (keratinized) Barrier (4.3e)

Stratified Squamous Epithelium Location of keratinized version: –Epidermis. Palms and soles of feet are typically heavily keratinized. Locations of non- keratinized version: –Lining of oral cavity and surface of tongue –Lining of esophagus –Lining of vagina and anal canal Non-keratinized stratified squamous epithelium What do the regions that contain the non- keratinized version have in common?

Stratified Squamous Epithelium Functions: –Protection! –Keratinized version (a.k.a. dry epithelium) protects against mechanical abrasion, water loss, and pathogen entry. Keratin is very strong, waterproof, and is bacteriostatic (prevents bacteria from reproducing).

Stratified Cuboidal Epithelium Microscopic Appearance: –2 or more layers of cells. –Surface layers are square or round (cuboidal). Locations: –Some sweat gland ducts. –Ovarian follicle

Stratified Cuboidal Epithelium Functions: –Contributes to sweat secretion. –Secretion of ovarian hormones (e.g., estrogens) To the left, we have an oocyte (egg cell) surrounded by stratified cuboidal epithelium. The oocyte is circled in blue

Stratified Columnar Epithelium Microscopic Appearance: –2 or more layers of cells. –Surface cells tall and narrow with basally located nuclei. Locations: –Rare. –Small portions of anal canal, pharynx, epiglottis, and male urethra.

Transitional Can change shape to accommodate changes in volume Ureter & urinary bladder only (4.3h)

Glands (type of epithelium) Exocrine glands – ducts Endocrine glands – ductless

Exocrine Gland Shapes Simple or compound (duct branches) Tubular or alveolar Tubuloalveolar 4.11

Skin (Integument) Figure 5.3

Figure 5.2 Layers of the Epidermis: Stratum Basale (Basal Layer)