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Copyright © 2008 Lippincott Williams & Wilkins. Chapter 7 Introduction to Cell Physiology

Introduction to Cell Physiology

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Page 1: Introduction to Cell Physiology

Copyright © 2008 Lippincott Williams & Wilkins.

Chapter 7

Introduction to Cell Physiology

Page 2: Introduction to Cell Physiology

Copyright © 2008 Lippincott Williams & Wilkins.

Chemotherapeutic AgentsChemotherapeutic Agents

• Alter cellular function or disrupt cellular integrity, causing cell death

• Prevent cellular reproduction, eventually leading to cell death

Page 3: Introduction to Cell Physiology

Copyright © 2008 Lippincott Williams & Wilkins.

Chemotherapeutic DrugsChemotherapeutic Drugs

• Destroy organisms that invade the body

– Bacteria, viruses, parasites, protozoa, fungi

• Destroy abnormal cells within the body

– Neoplasms and cancers

Page 4: Introduction to Cell Physiology

Copyright © 2008 Lippincott Williams & Wilkins.

Parts of a Human CellParts of a Human Cell

• Nucleus

• Cell membrane

• Cytoplasm

Page 5: Introduction to Cell Physiology

Copyright © 2008 Lippincott Williams & Wilkins.

Structure of a CellStructure of a Cell

Page 6: Introduction to Cell Physiology

Copyright © 2008 Lippincott Williams & Wilkins.

Cell NucleusCell Nucleus

• Contains genetic material

– Necessary for cell reproduction

– Regulates cellular production of proteins

• Each cell is “programmed” by the genes for the production of specific proteins

– Allows the cell to carry out its function

– Maintains cell homeostasis or stability

– Promotes cell division

Page 7: Introduction to Cell Physiology

Copyright © 2008 Lippincott Williams & Wilkins.

Cell MembraneCell Membrane

• Surrounds the cell

• Separates the intracellular fluid from the extracellular fluid

• Essential for cellular integrity

Page 8: Introduction to Cell Physiology

Copyright © 2008 Lippincott Williams & Wilkins.

Structure of a Lipid Cell MembraneStructure of a Lipid Cell Membrane

Page 9: Introduction to Cell Physiology

Copyright © 2008 Lippincott Williams & Wilkins.

Organelles of the CytoplasmOrganelles of the Cytoplasm

• Mitochondria

• Endoplasmic reticulum

• Free ribosomes

• Golgi apparatus

• Lysosomes

Page 10: Introduction to Cell Physiology

Copyright © 2008 Lippincott Williams & Wilkins.

Components of Cell MembraneComponents of Cell Membrane

• Cell membrane is made up of lipids and proteins

• Several lipids make up the cell membrane

– Phospholipids

– Glycolipids

– Cholesterol

• Lipid layer provides a barrier for the cell and maintains homeostasis of the cell

Page 11: Introduction to Cell Physiology

Copyright © 2008 Lippincott Williams & Wilkins.

Receptor SitesReceptor Sites

• Found on the cell membrane

• Specific receptor sites allow interaction with various chemicals

Page 12: Introduction to Cell Physiology

Copyright © 2008 Lippincott Williams & Wilkins.

Identifying MarkersIdentifying Markers

• Surface antigens

• Important in the role of cellular immunity

• Histocompatibility proteins allow for self-identification

• The body’s immune system recognizes these proteins and acts to protect self-cells and to destroy non–self-cells

Page 13: Introduction to Cell Physiology

Copyright © 2008 Lippincott Williams & Wilkins.

ChannelsChannels

• Channels or pores allow for the passage of substances into and out of the cell

• Some drugs are designed to affect certain channels within the cell

Page 14: Introduction to Cell Physiology

Copyright © 2008 Lippincott Williams & Wilkins.

Cell PropertiesCell Properties

• Endocytosis

– Involves incorporation of material into the cell

– Pinocytosis and phagocytosis occur

• Exocytosis

– Allows a cell to move a substance to the cell membrane and secrete the substance outside the cell

– Hormones, neurotransmitters, and enzymes are excreted into the body by this process

Page 15: Introduction to Cell Physiology

Copyright © 2008 Lippincott Williams & Wilkins.

Homeostasis of the CellHomeostasis of the Cell

• Passive transport

– Happens without the expenditure of energy and can occur across any semipermeable membrane

– Occurs by diffusion, osmosis, and facilitated diffusion

• Active transport

– Energy-requiring process

– Movement of particular substances against a concentration gradient

– Important in maintaining cell homeostasis

Page 16: Introduction to Cell Physiology

Copyright © 2008 Lippincott Williams & Wilkins.

Passive TransportPassive Transport

• Diffusion

– Does not require energy

– The movement of solutes from a region of high concentration to a region of lower concentration across a concentration gradient

• Osmosis

– Does not require energy

– Movement of water from an area low in solutes to an area high in solutes

Page 17: Introduction to Cell Physiology

Copyright © 2008 Lippincott Williams & Wilkins.

Phases of the Cell CyclePhases of the Cell Cycle

• G0 phase

– Resting phase

• G1 phase

– Gathering phase • S phase

– Synthesizing phase

• G2 phase

– Last substances needed for division are collected and produced

• M phase – Actual cell division occurs, producing two identical

daughter cells

Page 18: Introduction to Cell Physiology

Copyright © 2008 Lippincott Williams & Wilkins.

Cell CycleCell Cycle

Page 19: Introduction to Cell Physiology

Copyright © 2008 Lippincott Williams & Wilkins.

Cell PhysiologyCell Physiology

• May alter the cell membrane, causing the cell to rupture and die

• May deprive the cell of certain nutrients, altering the proteins that the cell produces and interfering with normal cell functioning and cell division

• May affect the normal cells of patients to some extent

Page 20: Introduction to Cell Physiology

Copyright © 2008 Lippincott Williams & Wilkins.

Chapter 8

Anti-infective Agents

Page 21: Introduction to Cell Physiology

Copyright © 2008 Lippincott Williams & Wilkins.

Drug Therapy Across the LifespanDrug Therapy Across the Lifespan

Page 22: Introduction to Cell Physiology

Copyright © 2008 Lippincott Williams & Wilkins.

Development of Anti-infective TherapyDevelopment of Anti-infective Therapy

• 1920s

– Paul Ehrlich worked on developing a synthetic chemical effective against infection-causing cells only

– Scientists discovered penicillin in a mold sample

• 1935

– The sulfonamides were introduced

Page 23: Introduction to Cell Physiology

Copyright © 2008 Lippincott Williams & Wilkins.

Mechanisms of ActionMechanisms of Action

• Interfere with biosynthesis of the bacterial cell wall

• Prevent the cells of the invading organism from using substances essential to their growth and development

• Interfere with steps involved in protein synthesis

Page 24: Introduction to Cell Physiology

Copyright © 2008 Lippincott Williams & Wilkins.

Mechanisms of Action (cont.)Mechanisms of Action (cont.)

• Interfere with DNA synthesis

• Alter the permeability of the cell membrane to allow essential cellular components to leak out

Page 25: Introduction to Cell Physiology

Copyright © 2008 Lippincott Williams & Wilkins.

Mechanism of Anti-infective AgentsMechanism of Anti-infective Agents

Page 26: Introduction to Cell Physiology

Copyright © 2008 Lippincott Williams & Wilkins.

Anti-infective ActivityAnti-infective Activity

• Anti-infectives vary in their effectiveness against invading organisms

• Some are selective: they are effective only for a small number of organisms

• Bactericidal: kill the cell

• Bacteriostatic: prevent reproduction of the cell

Page 27: Introduction to Cell Physiology

Copyright © 2008 Lippincott Williams & Wilkins.

Narrow Spectrum vs Broad SpectrumNarrow Spectrum vs Broad Spectrum

• Narrow spectrum of activity

– Effective against only a few microorganisms with a very specific metabolic pathway or enzyme

• Broad spectrum of activity

– Useful in treating a wide variety of infections

Page 28: Introduction to Cell Physiology

Copyright © 2008 Lippincott Williams & Wilkins.

Human Immune ResponseHuman Immune Response

• Goal of anti-infective therapy is reduction of the population of the invading organism

• Drugs that eliminate all traces of any invading pathogen might be toxic to the host as well

• Immune response is a complex process involving chemical mediators, leukocytes, lymphocytes, antibodies, and locally released enzymes and chemicals

Page 29: Introduction to Cell Physiology

Copyright © 2008 Lippincott Williams & Wilkins.

Problems With Treating Infections in Immunosuppressed Patients

Problems With Treating Infections in Immunosuppressed Patients

• Anti-infective drugs cannot totally eliminate the pathogen without causing severe toxicity in the host

• These patients do not have the immune response in place to deal with even a few invading organisms

Page 30: Introduction to Cell Physiology

Copyright © 2008 Lippincott Williams & Wilkins.

ResistanceResistance

• Anti-infectives act on a specific enzyme system or biological process; many microorganisms that do not act on a specific system are not affected by the particular drug

• This is considered natural or intrinsic resistance to that drug

Page 31: Introduction to Cell Physiology

Copyright © 2008 Lippincott Williams & Wilkins.

Acquired ResistanceAcquired Resistance

• Microorganisms that were once sensitive to the particular drug have begun to develop acquired resistance

• This results in serious clinical problems

Page 32: Introduction to Cell Physiology

Copyright © 2008 Lippincott Williams & Wilkins.

Ways Resistance Develops Ways Resistance Develops

• Producing an enzyme that deactivates the antimicrobial drug

• Changing cellular permeability to prevent the drug from entering the cell

• Altering transport systems to exclude the drug from active transport into the cell

• Altering binding sites on the membranes or ribosomes, which then no longer accept the drug

• Producing a chemical that acts as an antagonist to the drug

Page 33: Introduction to Cell Physiology

Copyright © 2008 Lippincott Williams & Wilkins.

Preventing ResistancePreventing Resistance

• Limit the use of antimicrobial agents to the treatment of specific pathogens sensitive to the drug being used

• Make sure doses are high enough, and the duration of drug therapy long enough

• Be cautious about the indiscriminate use of anti-infectives

Page 34: Introduction to Cell Physiology

Copyright © 2008 Lippincott Williams & Wilkins.

Identification of the PathogenIdentification of the Pathogen

• Identification of the infecting pathogen is done by culture

• A culture of a tissue sample from the infected area is done

– A swab of infected tissue is allowed to grow on an agar plate

– Staining techniques and microscopic examination identify the bacterium

• Stool can be examined for ova and parasites

Page 35: Introduction to Cell Physiology

Copyright © 2008 Lippincott Williams & Wilkins.

Sensitivity of PathogenSensitivity of Pathogen

• Shows which drugs are capable of controlling the particular microorganism

• Important to be done for microorganisms that have known resistant strains

• Along with a culture, identifies the pathogen and appropriate drug for treatment

Page 36: Introduction to Cell Physiology

Copyright © 2008 Lippincott Williams & Wilkins.

Factors Affecting Prescribing Anti-infective Agents

Factors Affecting Prescribing Anti-infective Agents

• Identification of the correct pathogen

• Selection of the right drug

– One that causes the least complications for that particular patient

– One that is most effective against the pathogen involved

Page 37: Introduction to Cell Physiology

Copyright © 2008 Lippincott Williams & Wilkins.

Combination TherapyCombination Therapy

• Use of a smaller dosage of each drug

• Some drugs are synergistic

• In infections caused by more than one organism, each pathogen may react to a different anti-infective agent

• Sometimes, the combined effects of the different drugs delay the emergence of resistant strains

Page 38: Introduction to Cell Physiology

Copyright © 2008 Lippincott Williams & Wilkins.

Adverse Reactions to Anti-infective TherapyAdverse Reactions to Anti-infective Therapy

• Kidney damage

• Gastrointestinal (GI) tract toxicity

• Neurotoxicity

• Hypersensitivity reactions

• Superinfections

Page 39: Introduction to Cell Physiology

Copyright © 2008 Lippincott Williams & Wilkins.

Prophylaxis of Anti-infective AgentsProphylaxis of Anti-infective Agents

• People traveling to areas where malaria is endemic

• Patients who are undergoing gastrointestinal or genitourinary surgery

• Patients with known cardiac valve disease, valve replacements, and other conditions requiring invasive procedures