Where is epithelial tissue commonly found and what are its functions?
Found in glands, lining cavities and hollow organs like digestive tract, and skin surface. Functions include protection, absorption, excretion, filtration, secretion, and sensory reception.
Name and describe the three types of membranes and their locations.
How is epithelial tissue classified by cell layers and shape?
By layers: Simple (one layer, for exchange), Stratified (multiple layers, for protection). By shape: Cuboidal (cube), Squamous (flat), Columnar (tall), Transitional (varied).
What are the five special characteristics of epithelial tissue?
Polarity (apical and basal surfaces), Regeneration, Avascular but innervated, Specialized contacts (desmosomes, tight junctions), Supported by connective tissue (basement membrane).
Define gland and differentiate between endocrine and exocrine glands.
A gland is one or more cells that secrete substances. Endocrine glands release hormones into blood without ducts; Exocrine glands release substances through ducts to surfaces.
What are the common components of connective tissue?
Common origin from mesenchyme, extracellular matrix with ground substance, cells (fibroblasts, mast cells, macrophages), and fibers (collagen, elastic, reticular).
Differentiate between loose and dense connective tissue with examples.
What are the three types of cartilage and their functions?
Hyaline: flexibility and resilience (ends of long bones, nose); Fibrocartilage: tensile strength and compression resistance (knee, vertebrae); Elastic: stretch and recoil (ear, larynx).
Describe the layers of the epidermis and their functions.
Stratum corneum: protection with dead keratinocytes; Stratum granulosum: keratinization and water resistance; Stratum spinosum: pre-keratin and dendritic cells; Stratum basale: stem cells and keratinocyte generation.
What are the two layers of the dermis and their tissue types?
Melanin, hemoglobin, carotene, and effects of UV radiation such as sunburns and tans.
What are the main functions of sweat and oil glands?
Sweat glands (eccrine and apocrine) regulate temperature and secrete sweat; Sebaceous glands secrete sebum to lubricate hair, act as antibacterial, and slow water loss.
Describe the structure and function of long bones.
Long bones have diaphysis (shaft with medullary cavity), epiphyses (ends with articular cartilage), compact bone, spongy bone, periosteum (external), and endosteum (internal).
What are the functions of bone tissue?
Support, protection, anchorage for muscles, mineral storage, fat storage, blood cell production, and hormone production (osteocalcin).
Explain bone remodeling and the role of calcium regulation.
Osteocytes detect stress and signal osteoclasts to resorb bone; osteoblasts then deposit new bone. Parathyroid hormone increases osteoclast activity when blood calcium is low, forming a negative feedback loop.
What are the cell types in bone and their functions?