Cells & Tissues Chapter 3 & 5

Cells & Tissues Tissues are groups of similar cells that perform a common function Human tissue can be categorized into 4 major groups: Epithelial Tissue Connective Tissue Muscle Tissue Nervous Tissue

Epithelial Tissue Epithelial tissues are found throughout the body, including: Covering the body surface and organs Inner lining of body cavities Lining of hollow organs Composes glands

Epithelial Tissue Lack blood vessels Epithelial tissues readily divide—injuries heal quickly as new cells replace the damaged ones Skin cells and cells that line the stomach and intestine Tightly packed—form protective barriers for the outer layer of the skin and the lining of the mouth There are 7 categories of epithelial cells

Simple squamous Simple squamous epithelial cells consist of a single layer of thin, flattened cells fitting tightly together Substances pass easily through simple squamous Easily damaged because it is so thin and delicate

Simple Cuboidal Simple cuboidal epithelial cells consist of a single layer of cube-shaped cells Simple cuboidal covers the ovaries and lines most of the kidney tubules

Simple Columnar Simple columnar cells are taller than they are wide Enables protection of whatever is underneath Simple columnar is a single layer of cells with elongated nuclei located near the bottom of the cell Can have cilia—help to move the egg cell down the uterine tube toward the uterus Nonciliated simple columnar lines the uterus and part of the digestive tract

Pseudostratified Columnar The cells in pseudostratified appear to be layered but they are not Nuclei sit at 2 or more levels in the row of cells May have cilia Line the passages of the respiratory system

Stratified Squamous Because of many cell layers, stratified squamous is relatively thick Cell divide in the deeper layers and the newer cells push the older cells to the outside Form the superficial layer of the skin, line the oral cavity and esophagus

Stratified Cuboidal Stratified cuboidal consists of two or three layers of cuboidal cells The layers provides more protection than a single layer Lines the ducts of mammary, sweat, salivary glands and the pancreas

Stratified Columnar Stratified columnar consists of several layers of skin The superficial cells are columnar The base layers are cuboidal Found in the male urethra and the larger ducts of glands

Connective Tissue Connective tissues bind structures, provide support and protections, serve as frameworks, fill spaces, store fat, produce blood cells, protect against infections, and help repair tissue damage Connective tissue cells can divide and typically have good blood supplies, but the density of blood vessels varies with the type of connective tissue

Connective Tissue Connective tissue can be categorized into 5 groups: Loose Connective Tissue Dense Connective Tissue Cartilage Bone Blood

Loose Connective Tissue Includes areolar tissue, adipose tissue, and reticular connective tissue Areolar tissue forms delicate, thin membranes Binds the skin to the organs underneath and fills the space between muscles

Loose Connective Tissue Adipose tissue (fat) develops when certain cells store fat as droplets in their cytoplasm and enlarge Lies beneath the skin, in spaces between muscles, around the kidneys, behind the eyeballs, surface of the heart, & around certain joints Reticular connective tissue is composed of thin fibers in a 3D network Helps provide the framework of certain internal organs

Dense Connective Tissue Many closely packed, thick, collagen fibers These fibers are very strong, which allows the tissue to withstand pulling forces Binds body structures as part of tendons and ligaments In the protective white layer of the eyeball and the deep skin layer

Cartilage Rigid connective tissue Provides support, frameworks, and attachments Protects underlying tissues Forms the structural models for many developing bones 3 forms: Hyaline cartilage—ends of bones in many joints, soft part of the nose, and in respiratory system Elastic cartilage—provides the framework for the external ears and parts of the larynx Fibrocartilage—intervertebral discs, cushions bones in the knees and in the pelvic girdle

Bone Most rigid connective tissue Hardness due to mineral salts, such as calcium phosphate and calcium carbonate Internally supports body structures Protects vital parts in the cranial and thoracic cavities Contains red marrow—makes blood cells

Blood Blood transports a variety of materials between interior body cells and those that exchange substances with the external environment 4 parts Red Blood Cells White Blood Cells Platelets Plasma

Muscle Tissue Muscle tissues are made up of cells called muscle fibers Able to contract and relax 3 kinds of muscle: Skeletal Muscle—forms muscles that typically attach to bone and can be controlled by conscious effort Smooth Muscle—composes the walls of hollow internal organs (stomach, intestines, bladder) Cardiac Muscle—only found in the heart

Nervous Tissue Nervous tissues are made of cells called neurons Found in the brain, spinal cord, and peripheral nerves Neurons sense changes in their surroundings and respond by conducting electrical impulses