Cytoplasmic Organelles Figure 3.4 The Nucleus Figure 3.1b

Cytoplasmic Organelles

Figure 3.4

The Nucleus

Figure 3.1b

Plasma Membrane

Figure 3.2

Plasma Membrane Specializations

• Membrane junctions– Tight junctions

• Impermeable junctions • Bind cells together into leakproof sheets

– Desmosomes • Anchoring junctions that prevent cells from being

pulled apart

– Gap junctions • Allow communication between cells

Plasma Membrane Specializations

Figure 3.3

Cytoplasmic Organelles

Figure 3.4

Rough Endoplasmic Reticulum

Figure 3.5, step 1

Ribosome

Protein

mRNA

Rough ER

As the protein is synthesizedon the ribosome, it migratesinto the rough ER cistern.

Rough Endoplasmic Reticulum

Figure 3.5, step 2

Ribosome

Protein

mRNA

Rough ER

As the protein is synthesizedon the ribosome, it migratesinto the rough ER cistern.

In the cistern, the protein foldsinto its functional shape. Shortsugar chains may be attachedto the protein (forming aglycoprotein).

Rough Endoplasmic Reticulum

Figure 3.5, step 3

Ribosome

Protein

Transportvesicle buds off

mRNA

Rough ER

As the protein is synthesizedon the ribosome, it migratesinto the rough ER cistern.

In the cistern, the protein foldsinto its functional shape. Shortsugar chains may be attachedto the protein (forming aglycoprotein).

The protein is packaged in atiny membranous sac called atransport vesicle.

Rough Endoplasmic Reticulum

Figure 3.5, step 4

Ribosome

Protein

Protein insidetransport vesicle

Transportvesicle buds off

mRNA

Rough ER

As the protein is synthesizedon the ribosome, it migratesinto the rough ER cistern.

In the cistern, the protein foldsinto its functional shape. Shortsugar chains may be attachedto the protein (forming aglycoprotein).

The protein is packaged in atiny membranous sac called atransport vesicle.

The transport vesicle buds fromthe rough ER and travels to theGolgi apparatus for furtherprocessing or goes directly tothe plasma membrane where itscontents are secreted.

Figure 3.6

Extracellular fluid

Plasma membrane

Golgi vesicle containingmembrane componentsfuses with the plasmamembrane

Golgi vesicle containingdigestive enzymesbecomes a lysosome

Proteins in cisterna

Lysosome fuses withingested substances

Membrane

Transportvesicle

Pathway 3

Pathway 2

Secretory vesicles Pathway 1

Golgiapparatus

Golgi vesicle containingproteins to be secretedbecomes a secretoryvesicle

Cisterna

Rough ER

Proteins

Secretion byexocytosis

Cytoplasmic Organelles

• Cytoskeleton– Network of protein structures that extend

throughout the cytoplasm– Provides the cell with an internal framework

Figure 3.7a

Figure 3.7b–d

Cytoplasmic Organelles• Cytoskeleton

– Three different types of elements

• Microfilaments (smallest)• Intermediate filaments• Microtubules (largest)

Cytoplasmic Organelles

• Centrioles– Rod-shaped bodies made of microtubules– Direct the formation of mitotic spindle during cell

division

Cellular Projections

• Not found in all cells• Used for movement

– Cilia move materials across the cell surface• Located in the respiratory system to move mucus

– Flagella propel the cell • The only flagellated cell in the human body is sperm

Cell Physiology: Membrane Transport

• Membrane transport—movement of substances into and out of the cell

• Two basic methods of transport– Passive transport

• No energy is required

– Active transport• Cell must provide metabolic energy (ATP)

Solutions and Transport

• Solution—homogeneous mixture of two or more components– Solvent—dissolving medium; typically water in the

body– Solutes—components in smaller quantities within

a solution• Intracellular fluid—nucleoplasm and cytosol• Interstitial fluid—fluid on the exterior of the

cell

Transport Terminology

Selective Permeability:• Passive Transport

– Diffusion– Osmosis

• Active Transport– Vesicular Transport– Exocytosis– Endocytosis

• Phagocytosis & Pinocytosis

Figure 3.11, step 1

Extracellular fluid

Cytoplasm

Binding of cytoplasmic Na+

to the pump proteinstimulates phosphorylationby ATP, which causes thepump protein to change itsshape.

ADP

Na+

Na+

Na+ P

ATP

Figure 3.11, step 2

Extracellular fluid

Cytoplasm

Binding of cytoplasmic Na+

to the pump proteinstimulates phosphorylationby ATP, which causes thepump protein to change itsshape.

The shape change expelsNa+ to the outside.Extracellular K+ binds,causing release of thephosphate group.

ADP

Na+

Na+

Na+

Na+

Na+

Na+

K+

K+

P

PP

ATP

Figure 3.11, step 3

Extracellular fluid

Cytoplasm

Loss of phosphate restoresthe original conformation ofthe pump protein. K+ isreleased to the cytoplasm andNa+ sites are ready to bind Na+

again; the cycle repeats.

Binding of cytoplasmic Na+

to the pump proteinstimulates phosphorylationby ATP, which causes thepump protein to change itsshape.

The shape change expelsNa+ to the outside.Extracellular K+ binds,causing release of thephosphate group.

ADP

Na+

Na+

Na+

Na+

Na+

Na+

K+

K+

K+

K+

P

PP

ATP

Active Transport Processes: Exocytosis

Figure 3.12b

Active Transport Processes: Endocytosis

Figure 3.13a, step 1

CytoplasmExtracellularfluid

Extracellularfluid

Plasmamembrane

Plasmamembrane

Ingestedsubstance

Pit

(a)

Active Transport Processes: Endocytosis

Figure 3.13a, step 2

CytoplasmExtracellularfluid

Extracellularfluid

Plasmamembrane

Detachmentof vesicle

Vesicle containingingested material

Plasmamembrane

Ingestedsubstance

Pit

(a)

Active Transport Processes: Endocytosis

Figure 3.13a, step 3

CytoplasmExtracellularfluid

Extracellularfluid

Plasmamembrane

Detachmentof vesicle

Vesicle containingingested material

Vesicle

Vesicle fusingwith lysosomefor digestion

Lysosome

Plasmamembrane

Ingestedsubstance

Pit

(a)

Active Transport Processes: Endocytosis

Figure 3.13a, step 4

CytoplasmExtracellularfluid

Extracellularfluid

Plasmamembrane

Detachmentof vesicle

Vesicle containingingested material

Vesicle

Vesicle fusingwith lysosomefor digestion

Release ofcontents tocytoplasm

Lysosome

Plasmamembrane

Ingestedsubstance

Pit

(a)

Active Transport Processes: Endocytosis

Figure 3.13a, step 5

CytoplasmExtracellularfluid

Extracellularfluid

Plasmamembrane

Detachmentof vesicle

Vesicle containingingested material

Vesicle

Vesicle fusingwith lysosomefor digestion

Release ofcontents tocytoplasm

Lysosome

Transport to plasmamembrane andexocytosis ofvesicle contents

Plasmamembrane

Ingestedsubstance

Pit

(a)

Active Transport Processes: Endocytosis

Figure 3.13a, step 6

Recycling of membraneand receptors (if present)to plasma membrane

CytoplasmExtracellularfluid

Extracellularfluid

Plasmamembrane

Detachmentof vesicle

Vesicle containingingested material

Vesicle

Vesicle fusingwith lysosomefor digestion

Release ofcontents tocytoplasm

Lysosome

Transport to plasmamembrane andexocytosis ofvesicle contents

Plasmamembrane

Ingestedsubstance

Pit

(a)

Active Transport Processes: Endocytosis

Figure 3.13b–c

Events of Cell Division

• Mitosis—division of the nucleus– Results in the formation of two daughter nuclei

• Cytokinesis—division of the cytoplasm– Begins when mitosis is near completion– Results in the formation of two daughter cells

Mitosis (divisionof nucleus)

GeneticallyIdentical“daughtercells”

S(DNA synthesis)

G1

G2 Cytokinesis(division of cytoplasm)

INTERPHASE (cell growth and chromosome duplication)

MITOTIC PHASE (M)

MITOSIS

Copyright © 2009 Pearson Education, Inc.

– Mitosis progresses through a series of stages– Prophase– Prometaphase– Metaphase– Anaphase– Telophase

– Cytokinesis often overlaps telophase

8.6 Cell division is a continuum of dynamic changes

Copyright © 2009 Pearson Education, Inc.

– A mitotic spindle is required to divide the chromosomes

– The mitotic spindle is composed of microtubules– It is produced by centrosomes, structures in the cytoplasm

that– Organize microtubule arrangement – Contain a pair of centrioles in animal cells

– The role of centrioles in cell division is unclear

8.6 Cell division is a continuum of dynamic changes

Copyright © 2009 Pearson Education, Inc.

Video: Animal Mitosis

Video: Sea Urchin (time lapse)

Centrosomes(with centriole pairs) Kinetochore

Early mitoticspindle

Chromatin

INTERPHASE PROMETAPHASEPROPHASE

Centrosome Fragmentsof nuclearenvelope

Plasmamembrane

Chromosome, consistingof two sister chromatids

Nuclearenvelope

Spindlemicrotubules

Nucleolus

Centromere

Metaphaseplate

Nucleolusforming

METAPHASE TELOPHASE AND CYTOKINESISANAPHASE

Cleavagefurrow

Daughterchromosomes

NuclearenvelopeformingSpindle

INTERPHASE

PROPHASE

PROMETAPHASE

METAPHASE

ANAPHASE

TELOPHASE AND CYTOKINESIS

– Metaphase– How many chromosomes are present in one human cell?– How many chromatids are present in one human cell?

8.6 Cell division is a continuum of dynamic changes

Copyright © 2009 Pearson Education, Inc.

– Applying Your KnowledgeHuman cells have 46 chromosomes. By the end of interphase

– How many chromosomes are present in one cell?– How many chromatids are present in one cell?

8.6 Cell division is a continuum of dynamic changes

Copyright © 2009 Pearson Education, Inc.

– Applying Your KnowledgeBy the end of anaphase

– How many chromosomes are present in one human cell?– How many chromatids are present in one human cell?

8.6 Cell division is a continuum of dynamic changes

Copyright © 2009 Pearson Education, Inc.

– Telophase– Applying Your Knowledge

By the end of telophase – How many chromosomes are present in one nucleus within the

human cell?– Are the nuclei identical or different?

8.6 Cell division is a continuum of dynamic changes

Copyright © 2009 Pearson Education, Inc.

– Cytokinesis– Applying Your Knowledge

By the end of cytokinesis – How many chromosomes are present in one human cell?– How many chromatids are present in one human cell?

8.6 Cell division is a continuum of dynamic changes

Copyright © 2009 Pearson Education, Inc.

Stages of Mitosis

• Prophase– First part of cell division– Centrioles migrate to the poles to direct assembly

of mitotic spindle fibers– DNA appears as double-stranded chromosomes– Nuclear envelope breaks down and disappears

Stages of Mitosis

• Metaphase– Chromosomes are aligned in the center of the cell

on the metaphase plate

Stages of Mitosis• Anaphase

– Chromosomes are pulled apart and toward the opposite ends of the cell

– Cell begins to elongate

Stages of Mitosis

• Telophase– Chromosomes uncoil to become chromatin– Nuclear envelope reforms around chromatin – Spindles break down and disappear

Stages of Mitosis

• Cytokinesis– Begins during late anaphase and completes during

telophase– A cleavage furrow forms to pinch the cells into

two parts

Stages of Mitosis

Figure 3.15, step 1

Centrioles

Plasmamembrane

Interphase

Nucleolus

Nuclearenvelope

Chromatin

Stages of Mitosis

Figure 3.15, step 2

Centrioles

Plasmamembrane

Interphase Early prophase

Nucleolus

Nuclearenvelope

Chromatin

Centrioles

Formingmitoticspindle

Centromere

Chromosome,consisting of twosister chromatids

Stages of Mitosis

Figure 3.15, step 3

Centrioles

Plasmamembrane

Interphase Early prophase Late prophase

Nucleolus

Nuclearenvelope

Spindlepole

Chromatin

Centrioles

Formingmitoticspindle

Centromere

Chromosome,consisting of twosister chromatids

Fragments ofnuclear envelope

CentromereSpindlemicrotubules

Stages of Mitosis

Figure 3.15, step 4

Metaphase

Sisterchromatids

Spindle Metaphaseplate

Stages of Mitosis

Figure 3.15, step 5

Metaphase Anaphase

Daughterchromosomes

Sisterchromatids

Spindle Metaphaseplate

Stages of Mitosis

Figure 3.15, step 6

Metaphase Anaphase Telophase and cytokinesis

Daughterchromosomes

Sisterchromatids

Nuclearenvelopeforming

Nucleolusforming

Spindle Metaphaseplate

Cleavagefurrow

PowerPoint® Lecture Slide Presentation by Patty Bostwick-Taylor, Florence-Darlington Technical College

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings

4

Skin and Body Membranes

Integumentary System

• Skin (cutaneous membrane)• Skin derivatives

– Sweat glands– Oil glands– Hair– Nails

Skin Functions

Table 4.1 (1 of 2)

Skin Functions

Table 4.1 (2 of 2)

Skin Structure

• Epidermis—outer layer– Stratified squamous epithelium– Often keratinized (hardened by keratin)

• Dermis– Dense connective tissue

Skin Structure

Figure 4.3

Skin Structure

• Subcutaneous tissue (hypodermis) is deep to dermis– Not part of the skin– Anchors skin to underlying organs– Composed mostly of adipose tissue

Layers of the Epidermis

• Stratum basale (stratum germinativum)– Deepest layer of epidermis– Lies next to dermis– Cells undergoing mitosis– Daughter cells are pushed upward to become the

more superficial layers• Stratum spinosum• Stratum granulosum

Layers of the Epidermis

• Stratum lucidum– Formed from dead cells of the deeper strata– Occurs only in thick, hairless skin of the palms of

hands and soles of feet• Stratum corneum

– Outermost layer of epidermis– Shingle-like dead cells are filled with keratin

(protective protein prevents water loss from skin)

Layers of the Epidermis

• Summary of layers from deepest to most superficial– Stratum basale– Stratum spinosum– Stratum granulosum– Stratum lucidum (thick, hairless skin only)– Stratum corneum

Melanin

• Pigment (melanin) produced by melanocytes• Melanocytes are mostly in the stratum basale• Color is yellow to brown to black• Amount of melanin produced depends upon

genetics and exposure to sunlight

Dermis

• Two layers– Papillary layer (upper dermal region)

• Projections called dermal papillae – Some contain capillary loops– Other house pain receptors and touch receptors

– Reticular layer (deepest skin layer)• Blood vessels• Sweat and oil glands• Deep pressure receptors

Dermis

• Overall dermis structure– Collagen and elastic fibers located throughout the

dermis• Collagen fibers give skin its toughness• Elastic fibers give skin elasticity

– Blood vessels play a role in body temperature regulation

Skin Structure

Figure 4.4

Normal Skin Color Determinants

• Melanin– Yellow, brown, or black pigments

• Carotene– Orange-yellow pigment from some vegetables

• Hemoglobin– Red coloring from blood cells in dermal capillaries– Oxygen content determines the extent of red

coloring

Skin Appendages

• Cutaneous glands are all exocrine glands– Sebaceous glands– Sweat glands

• Hair• Hair follicles• Nails

Appendages of the Skin

• Sebaceous glands– Produce oil

• Lubricant for skin• Prevents brittle hair• Kills bacteria

– Most have ducts that empty into hair follicles; others open directly onto skin surface

– Glands are activated at puberty

Appendages of the Skin

Figure 4.6a

Appendages of the Skin

• Sweat glands– Produce sweat – Widely distributed in skin– Two types

• Eccrine– Open via duct to pore on skin surface

• Apocrine– Ducts empty into hair follicles

Appendages of the Skin

Figure 4.6b

Sweat and Its Function

• Composition– Mostly water– Salts and vitamin C– Some metabolic waste– Fatty acids and proteins (apocrine only)

• Function– Helps dissipate excess heat– Excretes waste products– Acidic nature inhibits bacteria growth

• Odor is from associated bacteria

Appendages of the Skin

• Hair– Produced by hair follicle– Consists of hard keratinized epithelial cells– Melanocytes provide pigment for hair color

Appendages of the Skin

Figure 4.7c

Appendages of the Skin• Hair anatomy

– Central medulla– Cortex surrounds

medulla– Cuticle on outside of

cortex• Most heavily

keratinized

Figure 4.7b

Appendages of the Skin

• Associated hair structures – Hair follicle

• Dermal and epidermal sheath surround hair root

– Arrector pili muscle • Smooth muscle• Pulls hairs upright when cold or frightened

– Sebaceous gland– Sweat gland

Appendages of the Skin

Figure 4.7a

Appendages of the Skin

Figure 4.8

Appendages of the Skin

• Nails– Scale-like modifications of the epidermis

• Heavily keratinized

– Stratum basale extends beneath the nail bed• Responsible for growth

– Lack of pigment makes them colorless

Appendages of the Skin

• Nail structures– Free edge– Body is the visible attached portion– Root of nail embedded in skin– Cuticle is the proximal nail fold that projects onto

the nail body

Appendages of the Skin

Figure 4.9

Skin Homeostatic Imbalances

• Infections– Athlete’s foot (tinea pedis)

• Caused by fungal infection

– Boils and carbuncles• Caused by bacterial infection

– Cold sores• Caused by virus

Skin Homeostatic Imbalances

• Infections and allergies– Contact dermatitis

• Exposures cause allergic reaction

– Impetigo• Caused by bacterial infection

– Psoriasis• Cause is unknown• Triggered by trauma, infection, stress

Skin Homeostatic Imbalances

Figure 4.10

Skin Homeostatic Imbalances

• Burns– Tissue damage and cell death caused by heat,

electricity, UV radiation, or chemicals– Associated dangers

• Dehydration• Electrolyte imbalance• Circulatory shock

Rule of Nines

• Way to determine the extent of burns• Body is divided into 11 areas for quick

estimation• Each area represents about 9% of total body

surface area

Rule of Nines

Figure 4.11a

Severity of Burns

• First-degree burns– Only epidermis is damaged– Skin is red and swollen

• Second-degree burns– Epidermis and upper dermis are damaged– Skin is red with blisters

• Third-degree burns– Destroys entire skin layer– Burn is gray-white or black

Severity of Burns

Figure 4.11b

Critical Burns

• Burns are considered critical if– Over 25% of body has second-degree burns– Over 10% of the body has third-degree burns– There are third-degree burns of the face, hands, or

feet

Skin Cancer

• Cancer—abnormal cell mass• Classified two ways

– Benign• Does not spread (encapsulated)

– Malignant• Metastasized (moves) to other parts of the body

• Skin cancer is the most common type of cancer

Skin Cancer Types• Basal cell carcinoma

– Least malignant– Most common type– Arises from stratum basale

Skin Cancer Types

Figure 4.12a

Skin Cancer Types

• Squamous cell carcinoma– Metastasizes to lymph nodes if not removed– Early removal allows a good chance of cure– Believed to be sun-induced– Arises from stratum spinosum

Skin Cancer Types

Figure 4.12b

Skin Cancer Types

• Malignant melanoma– Most deadly of skin cancers– Cancer of melanocytes– Metastasizes rapidly to lymph and blood vessels– Detection uses ABCD rule

Skin Cancer Types

Figure 4.12c

ABCD Rule

• A = Asymmetry– Two sides of pigmented mole do not match

• B = Border irregularity– Borders of mole are not smooth

• C = Color– Different colors in pigmented area

• D = Diameter– Spot is larger then 6 mm in diameter