TISSUESStratified Squamous Epithelium

Cuboidal EpitheliumApical Meristems

Intercalary Meristems

PLANT TISSUE

S

PLANT ORGANS

The 3 primary organs found in plants are: Leaves Stems Roots

Since flowers are thought to have evolved from leaves, they are called “reproductive structures”.

Leaves, stems, roots, and flowers are all made up of various tissues.

PLANT TISSUES Plant Tissues fall into two large

categories:

Meristematic, or

Permanent (Non-Meristematic)

MERISTEMATIC TISSUES Meristems are places in plants where cell division is

occurring. During cell division, one cell becomes two cells. Each

new cell can also divide.

MERISTEMATIC TISSUES

In this class we will discuss three kinds of meristems:

Apical Meristems Intercalary Meristems Lateral Meristems

APICAL MERISTEMS In plants belonging to the DICOT class, apical meristems are located in BOTH the shoot tips and root tips. A shoot is simply a young, leaf-bearing stem.

In plants belonging to the MONOCOT class, apical meristems are located ONLY in the root tips.

Microscopic View of an Apical Meristem

APICAL MERISTEMS Apical

meristems cause PRIMARY GROWTH.

As cells in apical meristems divide and elongate, shoot tips and root tips grow longer. This increase in length is called primary growth.

Apical Meristem in a

Root Tip

APICAL MERISTEMS

•Primary growth of shoots and roots occurs as the cells of the apical meristem divide and elongate.

APICAL MERISTEMS A bud is a dormant

apical meristem. When conditions

are favorable for growth, buds “break” and begin pushing out new growth.

Bud Break

BUDS Buds come in 3 basic types:

Vegetative-produce stems and leaves.

Flower-produce only flowers. Mixed-produce stems/leaves and flowers.

MIXED BUDS OF CORNUS ALTERNIFOLIA

1 2

3 4

INTERCALARY MERISTEMS

In addition to the apical meristems located in their root tips, plants in the MONOCOT class have special meristems called intercalary meristems.

Intercalary meristems are located on monocots where the leaf bases connect to the stem of the plant.

INTERCALARY MERISTEMS

Monocots, like grasses, have intercalary meristems which

allow the leaves to grow back after mowing.

LATERAL MERISTEMS In addition to the

apical meristems located in the shoot and root tips, plants in the DICOT class have lateral meristems.

Lateral meristems cause SECONDARY GROWTH.

Secondary growth causes stems and roots to grow larger in diameter.

Lateral Meristems cause an increase in

stem diameter

LATERAL MERISTEMS MONOCOTS do not have lateral

meristems. Lateral meristems come in two basic

types: Vascular cambium; meristematic

tissue located between the xylem and phloem. The vascular cambium makes new xylem and phloem cells.

Cork cambium; meristematic tissue located just below the bark in woody dicot stems. The cork cambium makes new bark cells.

LATERAL MERISTEMS

Phloem

Vascular Cambium

Xylem (Wood)Cross Section of a Woody Dicot Stem

Vascular Cambium

Woody Dicot Stem

Cork CambiumCork (Bark)

PERMANENT TISSUES Permanent tissues are non-meristematic.

The following permanent tissues will be discussed: epidermis xylem phloem fibers

EPIDERMIS The epidermis

covering the leaves of plants contains thousands of tiny pores called stomata. The singular of stomata is stoma.

Stomata are usually found on the underside of leaves.

An apple leaf contains 39,000 stomata per square centimeter!

Stoma in Fuchsia

EPIDERMIS In most plants the cells of the upper and lower leaf epidermis secrete a waxy substance that covers the leaf and prevents water loss.

This waxy secretion is called a cuticle.

Leaf with Cuticle

Cuticle

XYLEM Xylem tissue conducts

water and dissolved mineral nutrients.

It is composed of columns of vessel cells (tracheids in gymnosperms), stacked one upon another, and fibers.

Vessel cell walls are pitted and allow water passage between the xylem and surrounding tissues. Mature xylem cells are dead.

Xylem Phloem

PHLOEM Phloem tissue conducts

the food produced by the leaves in a downwards direction to stems and roots (from source to sink).

Phloem is composed of sieve tubes, companion cells, and fibers.

The end walls of the sieve tubes are called sieve plates.

Xylem Phloem

FIBERS

Fiber cells have thick walls. A cluster of fiber cells is called a fiber.

Fibers are associated with the xylem and phloem of both monocots and dicots.

Fibers provide strength and support to xylem and phloem.

Fiber Cell - the cell wall is stained dark

red.

FIBERS

A cluster of many fiber cells make up a

fiber

FIBERS

Cortex

Xylem

Phloem

Fibers

Vascular Bundles in Corn

ANIMAL TISSUE

CATEGORIES OF TISSUES

Epithelium Connective Muscle Nervous

.

EPITHELIUM Lines, covers, and protects

other tissues and organs. Characterized by:

Cells tightly junked together The presence of a cell secretion

called the basement membrane. Named by:

Cell shape Other characteristics of the

cells. Squamous, Cuboidal, and

Columnar.

SQUAMOUS EPITHELIUM

Cells very thin, much wider than they are thick. Simple Squamous Epithelium

Air sacs of respiratory Lining of blood vessels, heart and lymphatic tubes

Stratified Squamous Epithelium Skin Vagina Esophagus Mouth

.

EXAMPLES OF SIMPLE SQUAMOUS EPITHELIUM

.

STRATIFIED SQUAMOUS EPITHELIUM

.

CUBOIDAL EPITHELIUM Cells cube shaped- secretion and

absorption. Kidney tubules Duct and small glands Surface of ovary

.

COLUMNAR EPITHELIUM Elongated cells, much longer than they

are wide. Simple Columnar Epithelium

A single layer of cells that line the digestive tract, gallbladder and excretory ducts of some glands. Has microvilli at surface for absorption.

Pseudostratified ciliated columnar epithelium

Lines the bronchi, trachea, uterine tubes and some of the uterus. Propels mucus or reproductive cells by ciliary action. .

SIMPLE COLUMNAR EPITHELIUM

.

PSEUDOSTRATIFIED CILIATED COLUMNAR EPITHELIUM

.

CONNECTIVE TISSUE Characterized by the cells widely separated

from each other in a matrix that is produced by the cells.

Tissue protects and supports. Cell Matrix composed of two regions

Ground Liquid (sol), Gel, Gum or solid

Fibers Non-elastic (= white or Collagen) Elastic (= yellow fibers)

Types of Connective tissue.

TYPES OF CONNECTIVE TISSUE

Loose (Areolar) Connective Tissue Dense Connective Tissue Adipose Cartilage Bone Blood

.

LOOSE CONNECTIVE TISSUE (AREOLAR)

Gel like ground with both elastic and non-elastic fibers running though the ground in many directions. Wraps and cushions organs Under the skin

.

DENSE REGULAR CONNECTIVE TISSUE

Nuclei and fibers arranged in parallel rows. Tendons and ligaments Fibers mostly non-elastic

.

ADIPOSE (FAT) Function as storage cells for adipose (lipids) Adipose cells contain a large vacuole which in

the live cell contains lipids. Cell nucleus and cytoplasm are pushed out to

edge of cell membrane.

.

CARTILAGE Ground of matrix is gum like. Cells are found in Lacunae within the matrix. Fibers may be elastic or non-elastic, or a

form of non-elastic called reticular(where the non-elastic fibers of very thin) Hyaline Cartilage-example on the ends of bones Elastic Cartilage- example ear cartilage Non-elastic Cartilage- example nose cartilage.

.

HYALINE CARTILAGE

.

ELASTIC CARTILAGE

.

BONE Ground of matrix is Solid (Calcium

carbonate). Has blood supply and nerves running

through the Haversian canal systems.

.

VASCULAR TISSUE (BLOOD) Liquid matrix = plasma

90% water 10%Plasma proteins, electrolytes,

hormones, oxygen, glucose etc. Formed elements

Erythrocytes -48billion(female) to 54 billion (male) cell / ml of blood in humans. Mammals are enucleated while rest of the vertebrates they have nuclei

Leukocytes -about 7.5 million / ml of blood Platelets -blood clotting

.

BLOOD

.

MUSCLE TISSUE Tissue with cells having fibers specialized for contraction.

Skeletal Muscle (Striated, voluntary) Parallel elongated cells (fibers) multinucleated and each cell is the length of the muscle. Light meat, Dark meat—Slow twitch, fast twitch muscle

Smooth Muscle (Visceral, involuntary) Cells are long and tapered. Organized into sheets of muscle.

Cardiac Muscle Intercalated disc Myogenic branched

.

SKELETAL MUSCLE

.

SMOOTH MUSCLE

.

CARDIAC MUSCLE

.

NERVOUS TISSUE Cells specialized to polarize

and depolarize. Cell is a neuron

.

END OF TISSUE PRESENTATION

.

NAME- KESHAVCLASS-9th

SECTION-CROLL NO-15