Plant and Animal Tissues PDF

Plant and Animal Tissues  3 Main Tissue Systems – Dermal Tissue Is like the “skin” of the plant. Typically consists of a single layer of epidermal cells. Often covered with a thick waxy layer that protects against water loss and injury, known as cuticle....

Plant and Animal Tissues  3 Main Tissue Systems – Dermal Tissue Is like the “skin” of the plant. Typically consists of a single layer of epidermal cells. Often covered with a thick waxy layer that protects against water loss and injury, known as cuticle. Some have tiny projections known as trichomes which help protect the leaf and also give it a fuzzy appearance. In roots, it includes root hair cells that provide a large amount of surface area and aid in water absorption. On the underside of leaves, it contains guard cells which regulate water loss and gas exchange. – Vascular Tissue – Is like the plant’s “bloodstream,” transporting water and nutrients throughout the plant. – Has principal subsystems and contains several types of specialized cells: Xylem – water-conducting tissue – Tracheids are present in all seed plants. They are long, narrow cells with walls that are impermeable to water. Their walls are pierced by openings that connect neighbouring cells to one another when they mature, they die and their cytoplast disintegrates. – Vessel elements are much wider than tracheids. They mature and die before they conduct water. They are arranged and to end on top of one another like a stack of tin cans. Cell walls are lost when they die, transforming the stack of vessel elements into a continuous tube through which water can move freely.  Phloem – food-conducting tissue – Sieve tube elements are like vessel elements; they have small holes where materials can move from one adjacent cell to another. When mature, they lose their nuclei and most of the other organelles in their cytoplasm. It is a pipeline through which sugars and other foods are carried in a watery system. – Companion cells surround the sieve tube elements. They keep their nuclei and other organelles through their lifetime. They support the phloem cells and aid in the movement of substances in and out of the phloem stream.  Xylem – water conduction Phloem – sugar conduction (Campbell Biology 9th ed. 2011. Pearson Education Inc. publishing as Benjamin Cummings) – Ground Tissue Cells that lie between dermal and vascular tissues. Consists of 3 types of cells: – Parenchyma – main composition; have their walls and large central vacuoles surrounded by a thin layer of cytoplasm; packed with chloroplasts in the leaves , and are the sites of most of a plant’s photosynthesis. – Collenchyma – have strong, flexible cell walls that help support larger plants; familiar “strings” of a stalk of celery. – Sclerenchyma – have extremely thick, rigid cell walls that make ground tissue tough and strong. (http://images.slideplayer.com/24/7006112/slides/slide_5.jpg) (http://images.slideplayer.com/24/7401588/slides/slide_3.jpg)  Meristematic Tissue – The only plant tissue that produces new cells by mitosis. Meristems are clusters of tissue that are responsible for continuing growth throughout a plant’s lifetime. – Apical meristem – group of undifferentiated cells that divide to produce increased length of stems and roots. – Floral meristem – produces the reproductive systems of flowering plants when genes are turned on in a shoot apical meristem and transformed it producing the modified leaves that become the petals. – Lateral meristem – growth in width. – Smooth muscles – not under voluntary control. – spindle-shaped, has one nucleus, and is not striated. – move food through digestive tract, control the way blood flows through the circulatory system, decrease the size of the pupils of the eyes in bright light. – Cardiac muscles – shares features with both skeletal and smooth muscles; striated, have one nucleus, but may have two (2); not under direct control of the Central Nervous System, and connected to their neighbours by gap junctions.  Epithelial Tissue—This type of tissue is commonly seen outside the body as coverings or as linings of organs and cavities. Epithelial tissues are characterized by closely- joined cells with tight junctions (i.e., a type of cell modification). Being tightly packed, tight junctions serve as barriers for pathogens,mechanical injuries, and fluid loss.  Cells that make up epithelial tissues can have distinct arrangements: cuboidal—for secretion simple columnar—brick-shaped cells; for secretion and active absorption simple squamous—plate-like cells; for exchange of material through diffusion stratified squamous—multilayered and regenerates quickly; for protection pseudo-stratified columnar—single layer of cells; may just look stacked because of varying height;for lining of respiratory tract; usually lined with cilia (i.e., a type of cell modification that sweeps the mucus).  Connective Tissue—These tissues are composed of the following: BLOOD —made up of plasma (i.e., liquid extracellular matrix); contains water, salts, and dissolved proteins; erythrocytes that carry oxygen (RBC), leukocytes for defense (WBC), and platelets for blood clotting.  CONNECTIVE TISSUE PROPER (CTP)—made up of loose connective tissue that is found in the skin and fibrous connective tissue that is made up of collagenous fibers found in tendons and ligaments. Adipose tissues are also examples of loose connective tissues that store fats which functions to insulate the body and store energy.  CARTILAGE —characterized by collagenous fibers embedded in chondroitin sulfate. Chondrocytes are the cells that secrete collagen and chondroitin sulfate. Cartilage functions as cushion between bones.  BONE —mineralized connective tissue made by bone- forming cells called osteoblasts which deposit collagen. The matrix of collagen is combined with calcium, magnesium, and phosphate ions to make the bone hard. Blood vessels and nerves are found at a central canal surrounded by concentric circles of osteons.  Muscle Tissue—These tissues are composed of long cells called muscle fibers that allow the body to move voluntary or involuntary. Movement of muscles is a response to signals coming from nerve cells. In vertebrates, these muscles can be categorized into the following: skeletal—striated; voluntary movements cardiac—striated with intercalated disk for synchronized heart contraction; involuntary smooth—not striated; involuntary  Nervous Tissue—These tissues are composed of nerve cells called neurons and glial cells that function as support cells. These neurons sense stimuli and transmit electrical signals throughout the animal body. Neurons connect to other neurons to send signals. The dendrite is the part of the neuron that receives impulses from other neurons while the axon is the part where the impulse is transmitted to other neurons. ANIMAL CELLS AND TISSUES (http://leavingbio.net/CELL%20DIVERSITY_files/image003.jpg) (https://facinatingamazinganimals.files.wordpress.com/2012/04/cell-types.gif)  Note: Form fits function Example: - simple squamous cells are flattened for faster exchange of materials - stratified squamous cells multilayered for protection - microvilli of columnar cells of the intestines increase surface area for absorption of nutrients - cilia sweeps inhaled particles away from lungs