DR /Noha Elsayed2014--2015

Anatomy &Physiology CLS 221

Cells and Tissues

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objectives

• Name the three main parts of a human cell.• Describe the structure and function of the plasma membrane.• Describe the structure and function of the nucleus.• Describe the structures and roles of the endoplasmic reticulum and

the Golgi apparatus in the cytoplasm.• Describe the structures of lysosomes and the role of these organelles

in the breakdown of molecules.• Describe the structure of mitochondria and their role in producing

ATP.• Describe the structures of centrioles, cilia, and flagella and their roles

in cellular movement.• Describe the structures and function of the cytoskeleton.• Describe how substances move across the plasma membrane, and

distinguish between passive and active transport.

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Cells and Tissues :-

CELL (the basic structural and functional unit of the living

things)

· Carry out all chemical activities needed to sustain life

· Cells are the building blocks of all living things

TISSUES

Tissues are groups of cells that are similar in structure and function.

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Anatomy of the Cell :-

· All the cells are not same

· All cells share general structures

· Cells are organized into three

Main regions

1. Nucleus

2. Cytoplasm

3. Plasma membrane

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1. The Nucleus :-

· Control center of the cell

· Contains genetic material

DNA (deoxyribonucleic acid)

· Three regions

· Nuclear membrane

· Nucleolus

· Chromatin

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Nuclear Membrane:-

· Barrier of nucleus

· Consists of a double phospholipid membrane

· Contain nuclear pores that allow for exchange of material with the rest of the cell

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Nucleoli :-

• Nucleus contains one or more nucleoli

• Sites of ribosome production

• Ribosomes then migrate to the cytoplasm through nuclear pores

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Chromatin :-

• Composed of DNA and protein

• Scattered throughout the nucleus

• Chromatin condenses to form chromosomes when the cell divides

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2. Plasma Membrane:- (outer most layer that surrounds the cytoplasm of

the cell)

• Barrier for cell contents

• Double phospholipid layer

– Hydrophilic heads

– Hydrophobic tails

• Other materials in plasma membrane

– Protein

– Cholesterol

– Glycoproteins

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Plasma Membrane:-

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Plasma Membrane Specializations:-

1. Microvilli

Finger-like projections

that increase surface area

for absorption.

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Plasma Membrane Specializations :-2. Membrane junctions

(site where two cells attached to each other)

· Tight junctions

· Desmosomes

· Gap junctions

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3. Cytoplasm:-

Material outside the nucleus and inside the plasma membrane

Cytosol

Fluid that suspends other elements

Organelles

Metabolic machinery of the cell

Inclusions

Non-functioning units

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Continue:-• Cytoplasmic Organelles:-

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Cytoplasmic Organelles

1- Ribosomes

• Made of protein and RNA

• Sites of protein synthesis

• Free in the cytoplasm

• Attached to rough endoplasmic reticulum

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2-Endoplasmic reticulum (ER)

Fluid-filled tubules for carrying substances

Two types of ER

Rough Endoplasmic Reticulum:-

• Studded with ribosomes

• Site where building materials of cellular membrane are formed

Smooth Endoplasmic Reticulum:-

• Functions in cholesterol synthesis and breakdown, fat metabolism, and

detoxification of drugs

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3-Golgi apparatus

Modifies and packages proteins

Produces different types of packages

• Secretory vesicles

• Cell membrane components

• Lysosomes

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• Cytoplasmic Organelles:-

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4- Lysosomes :-

Contain enzymes that digest

waste materials within the

cell.

5- Peroxisomes:-

– Membranous sacs of oxidase enzymes

– Detoxify harmful substances

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4-Mitochondria

· “Powerhouses” of the cell

· Change shape continuously

· Carry out reactions where oxygen is used to break down food

· Provides ATP (adenosine triphosphate) for cellular energy

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5-Cytoskeleton

· Three different types

· Microfilaments

· Intermediate filaments

· Microtubules

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6-Centrioles :-

· Rod-shaped bodies made of microtubules

· Direct formation of mitotic spindle during cell division

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Membrane Transport

Membrane Transport – movement of substance into and

out of the cell

Transport is by two basic methods :-

– Passive transport

No energy is required

– Active transport

The cell must provide metabolic energy

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• Solutions and Transport :-

Solution :- homogeneous mixture of two or more

components

Solvent – dissolving medium

Solutes – components in smaller quantities within a

solution

Intracellular fluid :-nucleoplasm and cytosol

Interstitial fluid:-fluid on the exterior of the cell

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Selective Permeability :-

The plasma membrane allows some materials to pass

while excluding others

This permeability includes movement into and out of the

cell

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• Passive Transport Processes:-

· Diffusion

Particles tend to distribute themselves evenly within a

solution

Movement is from high concentration to low concentration

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• Types of diffusion:

1-Simple diffusion

• Unassisted process

• Solutes are lipid-soluble materials or small enough

to pass through membrane pores

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2-Osmosis – simple diffusion of water

Highly polar water easily crosses the plasma membrane

)Movement of a solvent from an area of low concentration to one of high concentration(

3-Facilitated diffusion

Substances require a protein carrier for passive transport

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– Diffusion through the Plasma Membrane

Thank

you