Animal Organization and Homeostasis

Tissues  Specialized cells of the same type that perform a common function in the body  Types Epithelial Connective Muscular Nervous

Epithelial tissue  Covers surfaces and lines body cavities  Mostly functions in protection  Exposed to environment on 1 side, basement membrane on the other that anchors it to the connective tissue  Named according to shape of cell Squamous (flat), cuboidal (cube) and columnar (column) Stratified (layered), pseudosratified (looks layered)

Glandular epithelial  Secretes a product Exocrine  into a duct Endocrine  into the blood stream

Connective tissue  Most abundant  Each type has specialized cells Ground substance Protein fibers  Types Fibrous connective  (loose and dense) Adipose Cartilage Bone blood

Fibrous connective tissue  Contain fibroblast cells within a gel matrix  Loose fibrous – support  Adipose – energy reservoir, insulation  Dense fibrous – found in tendons and ligaments, contains collagen fibers

Supportive connective tissue  Cartilage – cells in chambers called lacunae surrounded by a gel like matrix  3 types of cartilage (based on fibers in matrix) Hyaline – most common, fine collagen fibers Elastic - more flexible Fibrocartilage – strong collagen fibers

Bone  Hard matrix of inorganic salts around protein fibers Compact bone – shaft of long bones  Cylindrical structures called osteons  Bone cells found within lacunae Spongy bone – end of long bones  Contains bony bars and plates with space between  Built for strength

Fluid Connective Tissues  Blood – formed elements and plasma Hematopoiesis – production of blood cells, in red bone marrow Transports nutrients and oxygen to tissue fluid, distribute heat and fluid, ion and pH balance RBC’s – small, no nucleus, round WBC – larger, have a nucleus, phagocytes, produce antibodies Platelets – involved in blood clotting Lymph – in lymph vessels, absorbs excess fluid

Muscular tissue  Made of cells called muscle fibers Actin – thin, myosin – thick Movement and generation of heat  3 types Skeletal – voluntary, striated Smooth – visceral, involuntary, no striations Cardiac – muscles of the heart, involuntary, striated, intercalated disks

Nervous tissue  Contain neurons (1 trillion on average) 3 parts: axon, cell body, dendrite Functions in sensory input, integration of data, and motor output  Neuroglia – support and nourish neurons Microglia - phagocyte Astroglia – provide nutrients Oligodendroglia – form myelin in brain

Organs and organ systems  Organ – 2 or more types of tissues working together to perform the same function  Organ system – organs working together to carry out a process

Skin  Largest organ  Functions for protection and thermoregulation  Contains receptors that monitor touch, pressure, temperature and pain  Epidermis  Dermis  subcutaneous

Epidermis  Stratified squamous  Hair follicles, sebaceous glands, sweat glands  Skin cells are pushed to surface of skin and slough off  Melanocytes – cells that produce melanin, pigment, UV rays induce production (vit.D)  Basal cell carcinoma and malignant melanoma are types of skin cancer

Dermis and Subcutaneous  Contains collagen and elastic fibers  Overstretching due to fast weight gain can cause stretch marks  Blood vessels and sensory receptors  Subcutaneous – not true part of skin, source of energy, produces padding, overall rounded appearance

Accessory organs of the skin  Nails – protective covering, can be useful medically  hair – begin in dermis, extend out of epidermis, dead, hardened epidermal cells Each follicle has an oil gland that when clogged, produces white heads or black heads (oxidized sebum)  Glands – sweat (sudoriferous)

Organ systems  2 main body cavities: Dorsal (cranial and vertebral cavity) Ventral (thoracic, abdominal and pelvic cavity)

Homeostasis  Maintaining and internal balance  Negative feedback – keeps a variable close to a particular value ex. – body temp.  Positive feedback – brings a greater change in the same direction ex. Oxytocin and birth