The Cell TheoryThe Cell Theory

Chapter 2Chapter 2

The CellThe Cell

All living things are made of cells.All living things are made of cells. Cells are the smallest living unit of life.Cells are the smallest living unit of life. Each cell performs the necessary Each cell performs the necessary

functions to sustain life.functions to sustain life. Cells can replicate themselves. Cancer Cells can replicate themselves. Cancer

occurs when cells replicate haphazzardly.occurs when cells replicate haphazzardly. Cellular function is carried out by Cellular function is carried out by

organelles.organelles.

Cellular reactions are mediated Cellular reactions are mediated (controlled) by ENZYMES. (controlled) by ENZYMES.

Enzymes speed up chemical reactions.Enzymes speed up chemical reactions. All the chemical reactions in the body All the chemical reactions in the body

make up its METABOLISM.make up its METABOLISM. There are 10 organelles that you are There are 10 organelles that you are

responsible for.responsible for.

Plasma MembranePlasma Membrane Outer covering of the cell.Outer covering of the cell. Also called the PLASMALEMMA.Also called the PLASMALEMMA. Separates the intracellular (inside) fluid Separates the intracellular (inside) fluid

and the extracellular (outside) fluid.and the extracellular (outside) fluid. Double layer of lipids (fat) with protein Double layer of lipids (fat) with protein

molecules between the layers.molecules between the layers.

Polar Head (like water)Polar Head (like water) Non-polar tails (do not like water)Non-polar tails (do not like water) Proteins within the membrane. They give Proteins within the membrane. They give

support to the membrane and prevent it support to the membrane and prevent it from collapsing.from collapsing.

Carbohydrates are attached to the Carbohydrates are attached to the integral proteins. These form the integral proteins. These form the GLYCOCALYX.GLYCOCALYX.

The glycocalyx is a sticky coat that allows The glycocalyx is a sticky coat that allows the cell to bind to other cells.the cell to bind to other cells.

The glycocalyx also serves as a marker.The glycocalyx also serves as a marker.

i.e.: certain antibiotics recognize the i.e.: certain antibiotics recognize the

glycocalyx and attach to the cell.glycocalyx and attach to the cell.

Functions of the Plasma Functions of the Plasma MembraneMembrane

Allows entry into the cell (Endocytosis)Allows entry into the cell (Endocytosis)

Phagocytosis – cell eatingPhagocytosis – cell eating

Pinocytosis – cell drinkingPinocytosis – cell drinking

Receptor-Mediated - hormonesReceptor-Mediated - hormones Allows movement out of cells Allows movement out of cells

(Exocytosis)(Exocytosis)

CytoplasmCytoplasm

Cytosol is a gel like substance which Cytosol is a gel like substance which holds all the internal cellular organelles.holds all the internal cellular organelles.

Contains ions, water, and enzymes.Contains ions, water, and enzymes.

THE ORGANELLESTHE ORGANELLES

Perform all the cellular functions.Perform all the cellular functions.

““Little Organs”Little Organs”

MITOCHONDRIAMITOCHONDRIA

Power plant of the Power plant of the cellcell

Produces energy Produces energy

RIBOSOMERIBOSOME

2 parts that make proteins.2 parts that make proteins.

RNA

Ribosome

ENDOPLASMIC ENDOPLASMIC RETICULUMRETICULUM

Subway system of the cell.Subway system of the cell. Network of membrane-walled tubes that Network of membrane-walled tubes that

twist through the cytoplasm.twist through the cytoplasm. ROUGH E.R. – have ribosomes ROUGH E.R. – have ribosomes

attached.attached. SMOOTH E.R. – do not have ribosomes SMOOTH E.R. – do not have ribosomes

attached.attached.

GOLGI APPARATUSGOLGI APPARATUS

Stacks of disk shaped membranes.Stacks of disk shaped membranes.

SortSort

Package proteins made in the ERPackage proteins made in the ER

ProcessProcess

LYSOSOMESLYSOSOMES

Sacs containing digestive enzymes that Sacs containing digestive enzymes that can break down almost all types of can break down almost all types of biological materials.biological materials.

PEROXISOMESPEROXISOMES

Contain oxidases (use oxygen to Contain oxidases (use oxygen to neutralize aggressive compounds known neutralize aggressive compounds known as free radicals).as free radicals).

Free radicals can damage cellular Free radicals can damage cellular proteins, membranes, and DNA if left to proteins, membranes, and DNA if left to accumulate.accumulate.

CYTOSKELETONCYTOSKELETON

System of complex rods that run System of complex rods that run throughout the cytoplasm.throughout the cytoplasm.

MicrotubulesMicrotubules MicrofilamentsMicrofilaments

CENTROSOMECENTROSOME

Contains a matrix and an inner pair of Contains a matrix and an inner pair of centrioles which are important in cellular centrioles which are important in cellular division.division.

NUCLEUSNUCLEUS

Membrane bound organelle which is the Membrane bound organelle which is the control center for all cellular activity..control center for all cellular activity..

Contains DNA – produce instructions for Contains DNA – produce instructions for protein synthesis.protein synthesis.

Contain chromosomesContain chromosomes

Produce ribsomes in the nucleolusProduce ribsomes in the nucleolus

Specialized Connections Between Cells - Desmosome

1 -  Microvilli

2 -  Zonula occludens

3 -  Zonula adherens

 4 - Desmosome

5 - Terminal Web

6- Interdigitation

Related Clinical TermsRelated Clinical Terms

NECROSIS – cellular death due to NECROSIS – cellular death due to disease or injury.disease or injury.

HYPERTROPHY – increase in size.HYPERTROPHY – increase in size.

i.e. Muscle cells become hypertrophic i.e. Muscle cells become hypertrophic in response to exercise.in response to exercise.

nucleus

Cell membrane

Rough Endoplasmic reticulum

mitochondria

Golgi apparatus

nucleolus

Nuclear membrane

Smooth Endoplasmic reticulum

TISSUESTISSUES

Chapter FourChapter Four

OBJECTIVES for TissuesOBJECTIVES for Tissues

Be able to list the four basic tissue types Be able to list the four basic tissue types and give examples of each.and give examples of each.

Describe the functions of each tissue Describe the functions of each tissue type.type.

Describe the cellular components of each Describe the cellular components of each tissue type.tissue type.

Describe and identify the morphology of Describe and identify the morphology of epithelial tissue types.epithelial tissue types.

TissuesTissues

Cells do not operate independently.Cells do not operate independently. Related cells work and operate together Related cells work and operate together

in organized groups.in organized groups.

The bottom line:The bottom line:

Tissues are clubs of cellular organization.Tissues are clubs of cellular organization.

Four Types of TissuesFour Types of Tissues

1. Epithelial Tissue1. Epithelial Tissue

2. Connective Tissue2. Connective Tissue

3. Muscle Tissue3. Muscle Tissue

4. Nervous Tissue4. Nervous Tissue

EPITHELIAL TISSUEEPITHELIAL TISSUE

Covers the body surface Covers the body surface

oror

Lines a body cavityLines a body cavity

Epithelial TissueEpithelial Tissue

Occurs at the interface of two different Occurs at the interface of two different environments.environments.

i.e. The epidermis is between the inside i.e. The epidermis is between the inside and the outside of the body.and the outside of the body.

Protects the body by detecting harmful Protects the body by detecting harmful stimuli.stimuli.

i.e. Receptors for pain are found within i.e. Receptors for pain are found within the skin.the skin.

SecretionSecretion

release of molecules from the cellrelease of molecules from the cell

AbsorptionAbsorption

bringing small molecules into the cell.bringing small molecules into the cell.

Ion transport – moves ions (charged Ion transport – moves ions (charged molecules) across a membrane.molecules) across a membrane.

The epithelium filters fluids that cross the The epithelium filters fluids that cross the barrier.barrier.

Characteristics of Characteristics of Epithelial TissueEpithelial Tissue

1. Cellularity 1. Cellularity – composed almost entirely of – composed almost entirely of cells.cells.

2. Specialized Contacts – 2. Specialized Contacts – connects adjacent connects adjacent cells.cells.

gap junctions, tight junctions, desmosomesgap junctions, tight junctions, desmosomes3. Polarity 3. Polarity – under surface called the – under surface called the

“basement membrane”.“basement membrane”.4. Avascular 4. Avascular – lacks blood vessels. Receives – lacks blood vessels. Receives

nutrients through the underlying connective nutrients through the underlying connective tissuetissue

5. 5. RegenerationRegeneration – replaces lost/dead – replaces lost/dead cells quickly.cells quickly.

Shapes of Epithelial Shapes of Epithelial TissueTissue

Simple Epithelium – one layerSimple Epithelium – one layer Stratified Epithelium – more than one Stratified Epithelium – more than one

layerlayer Squamous – cells are wider than tallSquamous – cells are wider than tall Cuboidal – cells are just about as tall as Cuboidal – cells are just about as tall as

widewide Columnar – cells are taller than wide.Columnar – cells are taller than wide.

An Illustrated View of Epithelial Types

Simple Cuboidal Epithelium

Simple Columnar Epithelium

Pseudostratified Ciliated Columnar Epithelium

Pseudostratified ciliated columnar epithelium with pale goblet cells. The different levels of nuclei are clearer here. Again, notice the wavy-looking cilia

Stratified squamous epithelium with beginning surface cornification. This section is from thin skin, which has a dry surface covered with dead cells. Notice how flat the surface cells are and how dark and pyknotic (degenerative) their nuclei have become. Again, notice the distinct row of basal cells.

CONNECTIVE TISSUECONNECTIVE TISSUE

Types of connective tissueTypes of connective tissue

FatFat

CartilageCartilage

Ligaments and TendonsLigaments and Tendons

BoneBone

BloodBlood

CollagenCollagen

Functions of Connective Functions of Connective TissueTissue

1. Support and bind other tissues. (tendons, 1. Support and bind other tissues. (tendons, ligaments)ligaments)

2. Hold body fluids (ground substance).2. Hold body fluids (ground substance). 3. Defend against infection3. Defend against infection - mast cells- mast cells - macrophages- macrophages - plasma cells- plasma cells - neutrophils- neutrophils 4. Store nutrients as fat. 4. Store nutrients as fat.

Mesenchyme -- embryonic c.t. with multipotential cells.

A stretched preparation

of areolar connective tissue. The pink fibers of different thicknesses are collagenous (or white) fibers. The dark, thin, more tortuous fibers are elastic (or yellow) fibers. Most of the nuclei belong to fibroblasts.

Fat cells -- note nucleus and rim of cytoplasm pushed to one side by the accumulation of fat. The lipid itself has been dissolved out in fixation. In the center of the picture, in the space bounded by the four large fat cells, there is a small, round cross-cut of a capillary with a dark, shrunken red blood cell inside.

Hyaline cartilage from the trachea

BLOOD - Neutrophil - Erythrocytes

1 – Erythrocyte

2 - Neutrophil

Muscle TissueMuscle Tissue

Brings about body movement.Brings about body movement. Moves by shortening.Moves by shortening. Three Types:Three Types:

1. skeletal – pulls on long bones. Striated.1. skeletal – pulls on long bones. Striated.

2. cardiac – only in the heart.2. cardiac – only in the heart.

3. smooth – no visible striations. Found in walls 3. smooth – no visible striations. Found in walls of hollow visceral organs such as digestive of hollow visceral organs such as digestive system, urinary organs, blood vessels, and system, urinary organs, blood vessels, and uterus. Mostly involuntary.uterus. Mostly involuntary.

1 -A Band  2 - Z Line 3 -  Intercalated disks

1 - Multinucleated skeletal muscle fibers

Skeletal Muscle Fibers

Smooth Muscle Tissue

1 – Smooth muscle fibers

2 – Artery endothelium

3- Artery Lumen

Nerve TissueNerve Tissue

Uses electrical impulses to transport Uses electrical impulses to transport information.information.

Can RegenerateCan Regenerate

1 - Glial cells 2 -  Neurons

Neurons

Identify the Following:

Epidermis

Dermis

Hair follicle

Subcutaneous fat

Pore

Epithelial Tissue

CT

Arrector Pilae Muscle

Nerve Endings

ALL FOUR TISSUE TYPES ARE USUALLY FOUND TOGETHER