cell structure & function - study-biology - home

1

2.5 : Cells are grouped into tissues

(A) Animal

CELL STRUCTURE & FUNCTION

CELL STRUCTURE AND FUNCTIONS

Prokaryotic and eukaryotic cells

Microscopic structures of plant and animal

cell

Structures & functions:Cell membrane and

organelles

Cell transport

Cells are grouped into tissue

Animal Plant

Epithelial Nerve Muscle Connective

MeristemParenchymaCollenchymaSclerenchyma Xylem Phloem

Types&

Specialized cell

From a ball of cells (embryo)…

Nerve cells

osteocytes Blood cells

Muscle cells

cell organization

cell

tissue

organ

system An integrated group of cell with

a common structure,

function, or both.

Types of tissues

epithelial

muscle

nerve

connective

Striated muscle

Smooth muscle

Cardiac muscle Bonecartilage blood

squamous

cuboidal

columnar

At the end of this lesson, student should be able to:

Describe the structure, distribution and function of the following cell:

a) Epithelial

b) Nerve

Simplest tissues.

It can be built up into tissues of varying complexity.

Lining tissues : in it simplest form, it consists of a single layer of cells covering the surface of the body and the organs within it.

A) Epithelial Tissues

Also lines various spaces and tubes ( in which situation it is usually referred to as endothelium).

Firmly attached to each other.

Rest on basement membrane

Have free surface

A) Epithelial Tissues

basement membrane

A) Epithelial Tissues

MAIN FUNCTION Protection

OTHER FUNCTIONS

•To increase the surface area for absorptionof material

•Exchange materials by diffusion

•As a gland ; secrete mucus and enzyme

TYPES EPITHELIAL

Cell

Shape

SIMPLE

- single layer of cells

STRATIFIED

- multiple layers of cells

PSEUDO-STRATIFIED

-single layer but it appears to be stratified because the cells vary in length

SQUAMOUS

CUBOIDAL

COLUMNAR

TYPES OF EPITHELIAL TISSUES

Simple EpithelialTissues

Stratified EpithelialTissues

PseudostratifiedEpithelialTissues

Simple squamousEpithelial tissues

Simple cuboidalEpithelial tissues

Simple columnarEpithelial tissues

Stratified squamousEpithelial tissues

Stratified columnar

Epithelial tissues

i) Simple Squamous Epithelial tissues

Cells are flattened

The sheet of cell is delicate, thin, and leaky

basement membrane

Exchange of materialLubricates the movement between adjacentsurfaceThe thinness of squamous facilitates diffusion across it

Lining of blood vesselsAir sacs of lungs

EPITHELIAL: SIMPLE SQUAMOUS

FUNCTION

DISTRIBUTION

ii)Simple Cuboidal Epithelial tissues

Cells are cubical in shape (dice-shaped)

View from free surface are polygonal

Have similar height and width

Nucleus in the centre

basement membrane

FUNCTION

Specialized for secretion

DISTRIBUTION

Make up the epithelial of kidney tubulesIn many glands ; thyroid & salivary glands

EPITHELIAL: SIMPLE CUBOIDAL

iii)Simple Columnar Epithelial tissues

Cells are elongated at the right angle of the basement membrane

Cell are taller compare to their width

Large cytoplasmic volume

Nucleus found lower in cell, closer to the cell base

Have numerous goblet cells (secrete mucus)

basement membrane

Secretion & absorption Secrete digestive juices and absorb nutrient

Linings of small intestine (many microvilli)Upper part of respiratory tract

EPITHELIAL: SIMPLE COLUMNAR

FUNCTION

DISTRIBUTION

Stratified Epithelial Tissues

Stratified squamousEpithelial tissues

Stratified columnarEpithelial tissues

i) Stratified Squamous Epithelial Tissues

Several layer of cells

Lower ones are columnar & metabolically active

Division of lower cells causes the older ones to pushed upward forward surface & becoming flattened as they move

Outer layer continuously

sloughed off and replaced

from below

FUNCTION

Provide protection from abrasion

DISTRIBUTION

Outer skinLinings of esophagus, anus and vagina.

EPITHELIAL: STRATIFIED SQUAMOUS

Consists of only 2 or 3 layers of cuboidal or low columnar cells

ii) Stratified Columnar Epithelial Tissues

FUNCTION

Provide more robust lining

DISTRIBUTION

Exocrine glandsSalivary glands

EPITHELIAL: STRATIFIED COLUMNAR

Pseudostratified Epithelium Tissues

The appearance looks like more than one layer of cells

True simple epithelial because all cells rest on basement membrane

Nucleus disposed at different levels.

Cilia are present

Mucus - secreting cilia

FUNCTION

Provide replacement for cells lost or damagedForm mucous membraneCilia – move the film of mucus along surface

DISTRIBUTION

Respiratory tract

EPITHELIAL: PSEUDOSTRATIFIED

Figure 40.1x Epithelial tissues

Figure 40.1 The structure and function of epithelial tissues

Identification of cell[shape, layer of cell]

FunctionDistribution

FINISH FOR EPITHELIAL TISSUES

Include:

Nerve tissues

NEURONS

NEUROGLIA

Nerve tissues…

Nerve cells

Fundamental unit of the nervous system

Having structure and properties that allow it to conduct signals by taking advantage of the electrical charge across its cell membrane

Include neuron and neuroglia or supporting cells

B) Nerve Cell

NEURONS

The pathway of the communication between the brain and the body

Transmit signals called nerve impulse

Receptor Effector(skin) (mucle/gland)

Include neuron and neuroglia or supporting cells

B) Nerve Cell

NEURONS

Impulse

Impulse pass along the nervous from organ that receive stimuli (receptor) such as skin to organ that effect change (effector) such as muscle or gland

Three part of neuronCell body Contain nucleus and other organelles

Dendrites Are short, highly branched Receive incoming stimulation and

conduct electric event to the cell body

Axon Axons much longer than dendrite Are enclose by an insulating layer

called the myelin sheath Single fibre extension that conduct

impulse away from the body cell

Further increase the speed of

transmission

( found throughout the Myelin sheath )

Myelin sheath

Nodes of Ranvier

Part of neuron

formed from Schwann

enclose the axon

Function: as electrical

insulation in a neuron and

accelerates impulse

transmission

Part of neuron

Cell Body

Dendrites

Axon

Nodes Of RanvierMyelin

Sheath

Contain nucleus and other organelles

-Formed from Schwann cell

-As electrical insulation and accelerates impulse transmission

• Short, highly branched

• received incoming stimuli and conduct electric event to cell body. -Single fiber extension

-Conduct impulse away from the body cell

Increase the speed of transmission

Types of neuron :

-classified by the number of their fibre or by their function

-The functional classification of neuron is based in which they transmit impulse and on the position

they occupy in the nervous system

Sensory neuron

Intermediary / Relay neuron

Motor neuron

Sensory neuron

Typical location :eye, surface of skin

Function :- receive information about body’s condition and external environment

- send impulse from sensory receptorto central nervous

system (CNS)

Types of neuron :

Intermediary / Relay

neuron

Typical location :brain and spinal cord

Function :integrate information, conduct impulse between neurons within CNS

Types of neuron :

Motor

neuron

Typical location :brain and spinal cord

Function :conduct impulse out of CNS toward muscles and glands

Types of neuron :

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Types of neuron :

Supporting cells in the central nervous system are called glial cell (glue cell)

Several types of glial cell in the brain and spinal cord glue neurons together

Do not conduct electrical impulse but instead support and insulate neurons

Neuroglia

Oligodendrocytes(CNS) and Schwann cell (PNS) are gliathat form an insulating covering (myelin sheath) around axon of many neuron

Neuroglia

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NERVOUS TISSUE

ANIMAL TISSUES TYPES AND SPECIALISED CELL: ANIMAL

Basic unit

NEURON

Types of neuron

Sensory neuron Interneuron Motor neuron

Support by

Neuroglia

Finish for nerve tissues