Animal Tissues

1. Animal Tissues • Felix Hernandez, M.D.

2. Organization of the Animal Body • Animals are multicellularheterotrophs whose cells lack cell walls • Animals developed external or internal skeletons to provide support, skin to prevent or lessen water loss, muscles that allowed them to move in search of food, brains and nervous systems for integration of stimuli, and internal digestive systems.

3. Epithelial Tissue • Epithelial tissue covers body surfaces and lines body cavities. • Functions include lining, protecting, and forming glands. Three types of epithelium occur: • Squamous epithelium is flattened cells. • Cuboidal epithelium is cube-shaped cells. • Columnar epithelium consists of elongated cells. • Any epithelium can be simple or stratified. • Simple epithelium has only a single cell layer. • Stratified epithelium has more than one layer of cells. • Pseudostratified epithelium is a single layer of cells so shaped that they appear at first glance to form two layers.

4. Epithelial Tissue

5. Epithelial Tissue • Functions of epithelial cells include: • movement materials in, out, or around the body. • protection of the internal environment against the external environment. • Secretion of a product.

6. Connective Tissue • Connective tissue serves many purposes in the body: • binding • supporting • protecting • forming blood • storing fats • filling space • Two types of connective tissue are Loose Connective Tissue (LCT) and Fibrous Connective Tissue (FCT). • Fibroblasts (LCT) are separated by a collagen fiber-containing matrix. • Collagen fibers provide elasticity and flexibility. • LCT occurs beneath epithelium in skin and many internal organs, such as lungs, arteries and the urinary bladder. This tissue type also forms a protective layer over muscle, nerves, and blood vessels.

7. Connective Tissue • Fibrous Connective Tissue has many fibers of collagen closely packed together. • FCT occurs in tendons, which connect muscle to bone. Ligaments are also composed of FCT and connect bone to bone at a joint. • Bone has calcium salts in the matrix, giving it greater rigidity and strength. Bone also serves as a reservoir (or sink) for calcium. • Two types of bone occur. • Dense bone has osteocytes (bone cells) located in lacunae connected by canaliculi. Lacunae are commonly referred to as Haversian canals. • Spongy bone occurs at the ends of bones and has bony bars and plates separated by irregular spaces. The solid portions of spongy bone pick up stress.

8. Bone

9. Connective Tissue • Blood is a connective tissue of cells separated by a liquid (plasma) matrix. • Two types of cells occur. • Red blood cells (erythrocytes) carry oxygen. • White blood cells (leukocytes) function in the immune system. • Plasma transports dissolved glucose, wastes, carbon dioxide and hormones, as well as regulating the water balance for the blood cells. • Platelets are cell fragments that function in blood clotting.

10. Muscle Tissue • Muscle tissue facilitates movement of the animal by contraction of individual muscle cells (referred to as muscle fibers). • Three types of muscle fibers occur in animals • skeletal (striated) • smooth • cardiac

11. Muscle Tissue • Skeletal (striated) muscle fibers have alternating bands perpendicular to the long axis of the cell. • These cells function in conjunction with the skeletal system for voluntary muscle movements. • Smooth muscle fibers lack the banding, although actin and myosin still occur. • These cells function in involuntary movements and/or autonomic responses (such as breathing, secretion, ejaculation, birth, and certain reflexes). • These fibers are components of structures in the digestive system, reproductive tract, and blood vessels.

12. Muscle Tissue • Cardiac muscle fibers are a type of striated muscle found only in the heart. • The cell has a bifurcated (or forked) shape, usually with the nucleus near the center of the cell. • The cells are usually connected to each other by intercalated disks

13. Nervous Tissue • Nervous tissue functions in the integration of stimulus and control of response to that stimulus. • Nerve cells are called neurons. • Each neuron has a cell body, an axon, and many dendrites. • Nervous tissue is composed of two main cell types: neurons and glial cells. • Neurons transmit nerve messages. • Glial cells are in direct contact with neurons and often surround them

14. Nervous Tissue

15. Nervous Tissue • all neurons have three parts. • Dendrites receive information from another cell and transmit the message to the cell body. • The cell body contains the nucleus, mitochondria and other organelles typical of eukaryotic cells. • The axon conducts messages away from the cell body

16. Review Questions • Which of these is not an animal tissue? a) connective; b) xylem; c) epithelial; d) nervous 2 • Tissues are made of _______. a) groups of cells that perform a different set of functions; b) collections of cells that perform similar or related functions; c) subellular structures that aid in the performance of the cell's role; d) none of these 2 • Which of these is NOT a function of epithelial tissue? a) covering surfaces; b) secretion; c) support of the body; d) lining internal exchange areas 3 • Layered epithelial tissue is referred to as which of these? a) squamous; b) stratified; c) voluntary; d) pseudostratified 4

17. Review Questions • Which of these cell types covers the inside of the mouth?  a) squamous epithelium; b) cartilage; c) blood; d) cuboidal epithelium 1 • Protection of the body from infectious organisms is accomplished by which of these tissues? a) bone; b) muscle; c) nerve; d) blood 4 • Linking of bone to bone in a skeletal system is accomplished by which of these tissues? a) epithelial; b) connective; c) muscle; d) nervous 2 • Cells that line the tubules in the kidney make up which of these tissues? a) adipose; b) squamous epithelium; c) cuboidal epithelium; d) stratified epithelium 3

18. Review Questions • The storage of fat is accomplished by which of these cell types? a) adipose; b) squamous epithelium; c) cuboidal epithelium; d) stratified epithelium 1 • Glands are composed of which of these tissue types? a) epithelium; b) connective; c) muscle; d) nervous 1 • Hard parts of the body would be made of which of these cell/tissue types? a) blood; b) bone; c) muscle; d) nerves 2 • Bone acts as a reservoir for which of these elements? a) carbon; b) nitrogen; c) calcium; d) hydrogen 3

19. Review Questions • The major function of bone is ___. a) covering body surfaces; b) support; c) movement; d) integration of stimulus 2 • New blood cells are formed in the ___. a) matrix; b) bone marrow; c) liver; d) adipose cells 2 • The blood cells that transport oxygen within the body are the ___. a) macrophages; b) erythrocytes; c) platelets; d) leukocytes 2 • The liquid part of the blood is ___. a) plasma; b) adipose; c) cartilage; d) platelets 1

20. Review Questions • When you move your arm to use your computer mouse, which of these muscle cell types is involved? a) cardiac; b) skeletal; c) smooth 2 • Contraction of your heart is accomplished by which of these cell types? a) cardiac; b) skeletal; c) smooth 1 • Contractions of the uterus during birth are accomplished by which of these cell types? a) cardiac; b) skeletal; c) smooth 3 • The junctions between nerve cells are known as ___. a) gap junctions; b) synapses; c) tight junctions; d) villi 2 • Transmission of the nerve message within the neuron is ___ in nature. a) chemical b) electrical 2