Essentials of Human Anatomy Physiology Copyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings Cell Diversity The Plasma Membrane Seventh

Essentials of Human Anatomy & Physiology

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Cell DiversityThe Plasma Membrane

Seventh EditionElaine N. Marieb

Chapter 3Cells and Tissues

Lecture Slides in PowerPoint by Jerry L. Cook

CellsCells

Slide 3.1Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Carry out all chemical activities needed to sustain life

Cells are the building blocks of all living things

Cells are not all the same

Cell DiversityCell Diversity

Slide 3.19aCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Figure 3.7; 1, 2


Slide 3.19bCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Figure 3.7; 3


Slide 3.19cCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Figure 3.7; 4, 5


Slide 3.19dCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Figure 3.7; 6, 7

CellsCells


All cells share general structures Cells are organized into three main

regions Plasma membrane Nucleus Cytoplasm

Cytosol + Organelles

Figure 3.1a

Plasma MembranePlasma Membrane


Barrier for cell contents – separates cytoplasm from the interstitial fluid

Double phospholipid layer Hydrophilic heads Hydrophobic tails

Other materials in plasma membrane Proteins – integral and peripheral Cholesterol Glycoproteins

Plasma MembranePlasma Membrane


Figure 3.2

Plasma Membrane Plasma Membrane SpecializationsSpecializations


Microvilli Finger-like

projections that increase surface area for absorption

Figure 3.3

Plasma Membrane Plasma Membrane SpecializationsSpecializations


Membrane junctions Tight junctions Desmosomes Gap junctions

Figure 3.3

Membrane FunctionsMembrane Functions


Membrane Transport Membrane Potential Cell Recognition

Membrane TransportMembrane Transport


Membrane Transport – movement of substance into and out of the cell through the membrane

Transport is by two basic methods Passive transport

No energy is required Active transport

The cell must provide metabolic energy

Solutions and TransportSolutions 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

Selective PermeabilitySelective Permeability


The plasma membrane allows some materials to pass while excluding others

This permeability includes movement into and out of the cell

Passive Transport ProcessesPassive Transport Processes


Diffusion Particles tend to distribute themselves

evenly within a solution Movement is

from high concentration to low concentration, or down a concentration gradient

Figure 3.8



Simple diffusion Unassisted process Lipid-soluble materials (non-polar)

Ex: O2, CO2, fats, steroids, urea, alcohol

Solutes small enough to pass through membrane pores

Ex: H2O, Na+



Simple diffusion



Osmosis – simple diffusion of water Water easily diffuses across the plasma

membrane from areas of high water concentration to areas of lower water concentration



Tonicity Words that describe the solution surrounding a

cell Isotonic solutions

Have same H2O concentration as cell interior No net movement of water Most IV solutions

D5W (5% glucose in water)Normal saline (0.9% NaCl in water)



Tonicity Hypertonic solutions

Have lower H2O concentration than cell interior Water moves out of cell Cause crenation (shriveling up ) of RBC’s



Tonicity Hypotonic solutions

Have higher H2O concentration than cell interior

Water moves into the cell Causes cells to burst if very hypotonic Examples

Distilled water½ Normal saline

½ D5W



Tonicity Which type of solution would the doctor

order for an extremely dehydrated patient? Which type of solution would the doctor

order for a patient with brain swelling?



Tonicity


Slide 3.24b

Facilitated diffusion Substances require a protein carrier for

passive transport

Diffusion through the Plasma Diffusion through the Plasma MembraneMembrane


Figure 3.9



Filtration Water and solutes are forced through a

membrane by fluid, or hydrostatic pressure A pressure gradient must exist

Solute-containing fluid is pushed from a high pressure area to a lower pressure area

Occurs at kidneys’ filtration membrane

Active Transport ProcessesActive Transport Processes


Transport substances that are unable to pass by diffusion They may be too large They may not be able to dissolve in the fat core

of the membrane They may have to move against a concentration

gradient Two common forms of active transport

Solute pumping Bulk transport



Solute pumping Amino acids, some sugars and ions are

transported by solute pumps ATP energizes protein carriers, and in most

cases, moves substances against concentration gradients

Video



Figure 3.10



Bulk transport (Video) Endocytosis

Extracellular substances are engulfed by being enclosed in a membranous vescicle

Types of endocytosis Phagocytosis – cell eating Pinocytosis – cell drinking



Figure 3.12



Bulk transport Exocytosis

Moves materials out of the cell Material is carried in a membranous vesicle Vesicle migrates to plasma membrane Vesicle combines with plasma membrane Material is emptied to the outside



Figure 3.11

Exocytosis – reverse of endocytosis

Membrane PotentialMembrane Potential


Figure 3.11

•Voltage across the membrane resulting from the separation of oppositely charged ions by the membrane.

•Na+ and K+ are constantly being pumped against their concentration gradients which maintains this voltage.

Cell RecognitionCell Recognition


Glycocalyx - glycoproteins on surface of cell Determine blood types Binding sites for some toxins Recognition of sperm by egg Determines lifespan of cells Immune response Embryonic development

Cell RecognitionCell Recognition


Glycocalyx

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Essentials of Human Anatomy Physiology Copyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings Cell Diversity The Plasma Membrane Seventh