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Animal Cells and Tissues. AP Biology. Animal Cells and Tissues. Four tissue types: Epithelial Connective Muscle Nervous. Cells, Tissues and Organs. Epithelial Tissue. Covers body surfaces and lines body cavities Three types: Squamous epithelium comprised of flattened cells
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Animal Cells and Tissues AP Biology
Animal Cells and Tissues Four tissue types: • Epithelial • Connective • Muscle • Nervous
Epithelial Tissue • Covers body surfaces and lines body cavities • Three types: • Squamous epithelium comprised of flattened cells • Cuboidal epithelium is made up of cube-shaped cells • Columnar epithelium consists of elongated cells
Squamous Epithelial Cells • Squamous cells have the appearance of thin, flat plates • Have horizontally flattened, elliptical nuclei because of the thin flattened form of the cell • Form the lining of cavities such as the mouth, blood vessels, heart and lungs and make up the outer layers of the skin
Cuboidal Epithelial Cells • Cuboidal cells are roughly square or cuboidal in shape • Each cell has a spherical nucleus in the center • Found in glands and in the lining of the kidney tubules
Columnar Epithelial Cells • Cells are elongated and column-shaped • Nuclei are elongated and are usually located near the base of the cells • Columnar epithelium forms the lining of the stomach and intestines • Some columnar cells are specialized for sensory reception such as in the nose, ears and the taste buds of the tongue
Simple epithelium made up of only one cell layer Stratified epithelium has more than a single layer of cells Epithelial Tissue
Functions of Epithelial Tissue • Movement of materials into, out of, or around the body • Protection of the internal environment against the external environment • Secretion of a product
Examples of Epithelial Tissues • Glands: • Intestinal goblet cells (single epithelial cells) • Endocrine glands (multicellular) • Many animals have skin that is composed of epithelium • Vertebrates have keratin in their epithelial cells to reduce water loss • Many invertebrates secrete mucus or other materials from their skin (earthworms)
Connective Tissue Serve many purposes in the body including: • Support • Protection • Binding • Blood formation • Fat storage • Fill space
Connective Tissue • Cells are separated from one another by a non-cellular matrix • This matrix may be: • Solid as in bone • Soft as in loose connective tissue • Liquid as in blood
Types of Connective Tissue • There are 3 main types of connective tissue • Loose Connective Tissue • FibrousConnective Tissue • Specialized Connective Tissues • Adipose Tissue (Fat) • Cartilage • Bone • Blood
Loose Connective Tissue (LCT) • Fibroblasts are separated by a collagen fiber-containing matrix • Collagen provides elasticity and flexibility • Occurs beneath epithelium in skin and many internal organs • Forms a protective layer over muscle, nerves and blood vessels
Fibrous Connective Tissue (FCT) • Consists of many collagen fibers closely packed together • Occurs in tendons, connecting muscle to bone • Make up ligaments, connecting bone-to-bone at a joint
Cartilage • Soft • Structural proteins deposited in the matrix between cells • Forms embryonic skeletons • Occurs in mature human adults in ears, joints and tip of nose
Bone • Hard • Calcium salts deposited in matrix • Serve as a sink for calcium • Proteins provide elasticity while minerals provide strength • Dense bone has osteocytes located in lacunae (Haversian canals) • Spongy bone occurs at the end of bones and absorb stress
Blood • Connective tissue separated by a liquid matrix called plasma • Red blood cells (erythrocytes) carry oxygen • White blood cells (leukocytes) function in the immune system • Platelets are cell fragments important in blood clotting • Plasma transports glucose, wastes, CO2, hormones and regulate water balance for the blood
Muscle Tissue • Facilitates movement by contraction of individual muscle cells referred to as muscle fibers • Found only in members of the animal kingdom • Three types: • Skeletal (Striated) • Smooth • Cardiac
Muscle Fibers • Multinucleated with nuclei just beneath the plasma membrane • Prominent striated, thread-like myofibrils • The fundamental unit of the muscle is the sarcomere • Each sarcomere consists of: • Thick filaments made of myosin at the center • Thin filaments made of actin attached to the Z line
Skeletal Muscle • Function in conjunction with the skeletal system in voluntary muscle movement • Striated with alternating bands at right angles to the long axis of the cell • The bands are areas of actin and myosin deposition
Smooth Muscle • Lack banding • Spindle shaped cells that form masses • Function in involuntary movements and/or autonomic responses like breathing, secretion, etc. • Make up structures in the digestive system, reproductive tract and blood vessels
Cardiac Muscle • Striated • Limited to the heart • Cells are forked, with nucleus near the center • Cells are connected together by disks • Intercalated disks
Nervous Tissue • Important in the integration of stimulus and control of the response to that stimulus • Made of nerve cells called neurons and glial cells (helper cells) • Neurons transmit nerve messages • Glial cells are in direct contact with neurons and often surround them
Nervous Tissue • The neuron is the functional unit of the nervous system • Variable in size and shape • Humans have about 100,000,000,000 (100 billion) neurons in their brain! Wow!
Nervous Tissue • Each neuron has a cell body, an axon and many dendrites • The cell body contains the nucleus, mitochondria and other organelles • The axon conducts messages away from the cell body • Dendrites receive information from other cells and direct them to the cell body