Animal organization and Homeostasis Chapter 31 Animal organization and Homeostasis

31.1 Types of Tissues

Types of Tissues Tissue- specialized cells of the same or similar type that perform a common function in the body. 4 types of tissues: Epithelial Connective Muscular Nervous

Epithelial Tissue Also called epithelium. Tightly packed cells that c over surface and lines body cavities. Sometimes involved in secretion, absorption, and excretion. Connected to one another by tight junctions, adhesion junctions, and gap junctions. One side exposed to environment while other side is attached to basement membrane (proteins that anchor it to connective tissue below).

Simple Epithelia Single layer of cells. Squamous- flat Cuboidal- cube-shaped Columnar- column-shaped Pseudostratified- looks like more that one layer but not. Cells in trachea that have cilia for mucus extraction.

Squamous Epithelial

Cuboidal Epithelial

Columnar Epithelial

Pseudostratified Epithelial

Stratified Epithelial Layers of cells piled on top of the other. Outer layer of your skin is stratified squamous epithelium, reinforced by keratin.

Glandular Epithelial When an epithelium secretes a product, it is said to be glandular. Glands that secrete through a duct are called exocrine glands. Glands that do not have a duct are called endocrine glands. Secrete hormones internally through blood stream.

Connective Tissue Most abundant and widely distributed. All have three components: Specialized cells Ground substance Protein fibers

Fibrous Connective Tissue Both loose and dense fibrous tissue have fibroblasts. Loose fibrous connective tissue- supports epithelium and internal organs.

Fibrous Connective Tissue Adipose tissue- bodies primary energy reservoir. Loose fibrous tissue compost of enlarged fibroblasts that store fat. These are called adipocytes. Insulates body Provides cushioning Found beneath skin You have a set amount of adipocytes. When you gain weight they swell. You do not get more fat cells. Obese individuals adipocytes might be 5X larger than normal.

Fibrous Connective Tissue Dense fibrous connective tissue- contains collagen fibers that are packed together. Found in tendons and ligaments.

Supportive Connective Tissue

Cartilage Cartilage- cells lie in small chambers called lacunae, separated by a matrix that is solid yet flexible. Lack direct blood supply, so it heals slowly. Three types: Hyaline Elastic Fibro

Hyaline Cartilage Have very fine collagen fibers White, translucent appearance Found in the nose and at the ends of long bones and ribs Fetal skeleton made of this. Later, it turns to bone.

Elastic Cartilage More elastic fibers than hyaline. Framework of the outer ear.

Fibrocartilage Has strong collagen fibers. Found in structures that withstand tension and pressure. Pads between vertebrae and wedges in knee joint.

Bone Bone- is the most rigid and consists of extremely hard matrix of inorganic salts, deposited around protein fibers.

Compact Bone Shaft of long bone. Has cylindrical structural units called osteons. Bone cells located in spaces called lacunae. The hollow shaft of long bones are filled with yellow bone marrow.

Spongy Bone At ends of a long bone. Contains numerous bony bars and plates separated by irregular spaces. Still designed for strength. Site of red bone marrow.

Fluid Connective Tissue Blood consists of formed elements and plasma. Transports nutrients and oxygen to interstitial and removes carbon dioxide and other wastes. Helps distribute heat and plays a role in fluid, ion, and pH balance.

Fluid Connective Tissue Red blood cells are small, disk-like shaped cells without a nucleus. Makes it concave in the middle. The red pigment hemoglobin makes the blood appear red. Iron, a part of hemoglobin, forms a loose association with oxygen.

Fluid Connective Tissue White blood cells are usually larger, have a nucleus, and are translucent. Fight infection Phagocytic and engulf infectious pathogens Produce antibodies, which bind to foreign substances and kills them Platelets- not complete cells. Present in bone marrow. Helps form a plug when something is damaged.

Fluid Connective Tissue Lymph- located in lymphatic vessels. Absorb interstitial fluid and return it to the blood. Lymph nodes, composed of fibrous connective tissue and white blood cells called lymphocytes, occur along lymphatic vessel. These remove foreign from lymph. Lymph nodes may be enlarged when these cells respond to infection.

Muscular Tissue Composed of cells called muscle fibers. These fibers contain actin filaments and myosin filaments. Generate body heat. 3 types

Skeletal Muscle Voluntary muscle Attached to bones of skeleton by tendons. When it contracts, body parts move. Contraction occurs faster than any other type of muscle. Fibers are cylinder shape and long. Fibers are alternating light and dark bands making them appear striated.

Smooth Muscle Does not have striations Spindle-shaped cells Not under voluntary control Found in the walls of the intestine, stomach, other organs, and blood vessels When it contracts, food moves or blood pressure is raised Small amount of it is found in the iris of the eye

Cardiac Muscle Found only in the walls of the heart. Its contraction pumps blood and accounts for the heartbeat. Has striations, but involuntary. Cells are separate but they are bound end to end by intercalated disks -areas where folded plasma membrane contain adhesion junctions and gap junctions.

Nervous Tissue Contains nerve cells called neurons and supporting cells called neuroglia.

Neurons Specialized cells that have three parts: Dendrites- conducts signals toward the cell body Cell body- major portion of cytoplasm and nucleus Axon- conducts nerve impulses away from the cell body. Long axons covered by a myelin sheath. Three functions: Sensory input Integration of data Motor output

Neuroglia In the brain, these cells out number neurons as much as ten to one. Supports and nourishes neurons New research shows they directly contribute to brain function. Three types: Microglia- engulf bacteria Astrocytes- provide nutrients Glial cell-derived growth factor- Parkinson's disease Oligodendrocytes- form myelin in the brain

Nervous Tissue Major difference between a neuron and neuroglia is that neuron of adults cannot undergo cell division, but neuroglial cells can. Brain tumors involve actively dividing neuroglial cells.

31.3 The Integumentary System

The Skin Integumentary system- skin its derivatives and its accessory organs. 15% of body weight. Some have scales, mucous glands, feathers, hair. Even whales have hair at some point in their life.

Functions Protects underlying parts from desiccation, trauma, and pathogen invasion. Regulates body temperature. Equipped with sensory structures that monitor touch,, pressure, temperature, and pain.

Regions Skin has two main regions: the epidermis and the dermis. A subcutaneous layer, the hypodermis, is found between the skin and muscle or bone. This is not part of the skin, just grouped with it.

The Epidermis Stratified squamous epithelium Either thin or thick Thin skin covers most of our body and is associated with hair follicles, oil glands, and sweat glands. Thick skin appears on our hands and soles of our feet. It has sweat glands, but no hair follicles or oil glands.

The Epidermis New cells become flattened and hardened as they push tot the surface. Hardening happens because cells produce keratin. 1.5 million of the cells are shed from your body everyday. A thick layer of dead, keratinized cells, arranged in spirals form finger and toe prints. Thought to help with gripping and increase friction.

The Epidermis Melanocytes- produce melanin. A tan is from your body trying to protect itself from the dangerous rays of the sun or tanning bed. Fungi can grow on skin. Dermatophytes-ring worm and athlete's foot.

The Dermis Dense fibrous connective tissue beneath epidermis. Contains collagen and elastic fibers. Prevent skin from being torn. Over stretching can cause stretch marks. Number of these fibers decrease with age, causing wrinkles with the help of the sun. Also contain blood vessels (someone blushes) Sensory receptors located here.

The Hypodermis Not part of the skin Loose connective tissue and adipose tissue. Helps insulate the body. Excessive development of this layer occurs with obesity.

Accessory Structures Nails- protective coverings of fingers and toes. Grow from epithelial cells at nail root. Cuticle hides the nail root.

Accessory Structures Hair follicles- begin in dermis and continue through epidermis. Contraction of the arrector pili causes the hair to stand on end. Cell division causes hair to grow. Hair is dead, hardened epidermal cells. Wavy- shaft is oval. Straight- shaft is round. Color depends on the pigmentation. Grows 1mm every 3 days.

Accessory Structures (hair cont.) You lose 50-100 hairs every day. Each follicle has one or more oil glands. Your skin has about 250,000 sweat glands. Modify body temperature.