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General Pathology VDMP832 > Normal Cells and Matrix > Flashcards

Normal Cells and Matrix Flashcards

1
Q

Cells

A

Cell are the organizational unit of an animal

Building blocks of tissues and organs

Provide a focal point for learning pathology

All cells originate form a singel primordial cells

This single cell differentiates into a diverse population of different cells

Cell functions are highly interrelated

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2
Q

Cell components:

Plasma Membrane

A
  • Lipid bilayer interspersed with membrane proteins
  • Membrane proteins are critical for cell function and communication
  • The membrane is fliud and constantly changing
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3
Q

Cell Component:

Cytosol

A

Cytosol is fluid that bathes all intracytoplasmic organelles

site of most intermediary metabolism

Accounts for 50-60% of the total cell volume

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4
Q

Cell Component:

Mitochondria

A

Responsible for energy production

Oxidative phosphorylation - 18x more effectient than anaerobic glycolysis

Energy is released as electrons move down the electron transport chain - ATP

May have originated as an intracellular prokaryote

Down side - reactive oxygen molecules, oxudative damage to the cells

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5
Q

Cell Component:

Endoplasmic Reticulum

A

Membrane-bound spave where proteins, lipids, and carbohydrates are produced.

These can be incorporated into organelles or are secreted

Rough ER produces proteins - contains ribosomes

Smooth ER produces lipids - detoxification reactions also occur here

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6
Q

Cell Component:

Golgi Apparatus

A

Membrane-bound sacs that are closely associated with the ER

Modifies, sorts and exports products of the ER

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7
Q

Cell Component:

Lysosomes

A
  • Membrane-Bound sace of enzymes
    • Primary lysosomes bud from the golgi apparatus
    • Secondary lysosmes are primary lysosomes that fuse with other organelles or cytoplasmic vacuoles
  • They degrade macromolecules and extracellular material taken up by the cell
    • Contents are predominately hydrolases
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8
Q

Cell Component:

Peroxisomes

A

Small enzyme-containing vesicles

Mainly a site of oxidative reactions

Catalase accounts for 40% of protein content

Catalase converts H2O2 to H2O

Detoxification and fatty acid breakdown also occur here

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9
Q

Cell Component:

Cytoskeleton

A

The cytoskeleton provides properties of shape, organization, and movement to a cell

Consists of a variety of proteins

Microfilaments - actin / myosin

Microtubules

Intermediate filaments

Regulatory proteins

Cytoskeleton assebly and disassembly is regulated by calcium

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10
Q

Cell Component:

Nucleus

A

The nucleus is the location of chromatin

Chromatin consists of cellular DNA and associated proteins

Chromatin is organized into chromosomes

Separated from the cytoplasm by a two-layered membrane - Nuclear Envelope

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11
Q

Life History of a cell:

Origins

A

All cells are derived from a single primordial cell; the zygote

There are 3 main embryogenic cell types:

Ectoderm

Mesoderm

Endoderm

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12
Q

Ectoderm

A

Forms a cephalic disc and the neural tube

Cells and tissues derived from ectoderm include:

Central and peripheral nervous systems

Sensory epithelium

Epidermis

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13
Q

Mesoderm

A

Somites located adjacent to the neural tube

Cells and tissues derived form mesoderm include:

Connective tissues (mesenchyme)

Fibroblasts, osteoblasts, chondroblasts

Muscle

Kidney

Heart and Blood vessels

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14
Q

Endoderm

A

Originates as a flat disc by the ectoderm

Cells and tissues derived from endoderm include:

Gastrointestinal Epithelium

Respiratory Epithelium

Parenchymal Organs:

Liver

Pancreas

Endocrine Glands

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15
Q

Life History of a cell:

Replication

A

The Cell Cycle

The cell cycle is complex adn critical to normal cell development and homeostasis

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16
Q

Cell Differentiation

A

Most cells are adapted to perform a specific Function

Neurons

Osteoblasts

Hepatocytes

Functions of cells are highly interrelated.

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17
Q

Developmental Anomalies

A

Growth and differentiation of each cell line needs to occur in a well orchestrated and corrdinatied manner of sad things can happen

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18
Q

How cells talk to eachother

A

A cell must be able to interact with it’s environment as well as other cells

Exchange nutrients and wastes, secretions of products, responding to stimuli, communication

Homeostasis

Coordination of activity

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19
Q

Cell Interactions

A
  • Mechanisms of interaction
    • Membrane pumps and enzyme systems
    • Receptors
      • hormones and cytokines
    • Cell-to-cell connections
      • Membrane interactions
      • Channels between adjacent cells
    • Exocytosis
    • Endocytosis
      • Pinocytosis
      • Phagocytosis
20
Q

Cell Function

A

Of critical importance is the interaction of a cell with other cells

This is essential for homeostasis

Mechanisms:

  • Autocrine
    • Self stimulation of a cell
  • Paracrine:
    • Stimulation of local cells only
  • Endocrine:
    • Stimulation of cells throughout the body
21
Q

Extracellular Matrix

A

This is the structural framework in which cells organize, move and interact

It provides sites for cell adhesion and a conduit for exchange of cell nutrients, and waste

It has structural, adhesive and absorptive components

22
Q

Properties of the ECM

A

Dictates tissue architecture and organizations

It has specific features for each tissue/organ

It regulates or modifies many cell activities

Serves as a reservoir of growth factors and bioactive molecules

It is constantly remodeling and changing

23
Q

Components of the ECM

A

the “Matrisome” consists of over 300 different protiens

These components fall into 3 categories:

  1. Structural
  2. Absorptive
  3. Adhesive
24
Q

Extracellular Matrix:

Structural

A

Structural components of the ECM build the framework for cells to exist upon and within

Structural Components Include:

  • Collagen
    • Many different types exist for different situations
  • Elastin
    • most prominent where elasticity is needed
25
Q

Collagen Types

A

There are at least 28 different types of collagen

  1. Type 1
    1. Structural collagen of most tissues
      1. fibrous tissue, bone
  2. Type 2
    1. Major component of cartilage
  3. Type 4
    1. Basement membranes
26
Q

Extracellular Matrix:

Absorptive

A

These absorb water and other soluble sunstances which bath surrounding cells

Major absorptive components:

  • Glycosaminoglycans (GAG)
    • polysaccharides consisting of 4 main groups:
      • Hyaluronic Acid
      • Heparan Sulfate
      • Chondroitin / Dermatan sulfate
      • Keratan Sulfate
    • Proteoglycans
      • There are proteins with a GAG side chain
    • These exert impotant osmotic pressures to help maintain water balance
27
Q

Extracellular Matrix:

Adhesive

A

Sites of attachment for structural ECM components and cells

Adhesive Components: Fibronectin, Laminin, and many others

Mediate interactions of fixed or mobile cells with the ECM

28
Q

Fibronectin

A

Cement

A cell adhesion that links cell membrane integrins to ECM components.

Collagen and Proteoglycans

29
Q

Laminin

A

Major component of basement membranes that binds cell membrane integrins

30
Q

ECM Abnormalities

A

The extracellular matrix impacts all organs and tissues in the body

Has recently been studied as a unique organ/system

Defects of any component can result in a wide variety of conditions

  • Skin, bone and joint disease
  • Muscles Disease
  • Fibrosis
  • Neoplasia
  • Cardiovascular Disease
  • Inflammation
31
Q

Connections Between Cells

A

Various Types of junctions link cells together to provide functional attributes to populations of cells

  • Adhering Junctions
  • Tight Junctions
  • Gap Junctions
  • Desmosomes and hemidesmosomes

Tissue function dictates the most appropriate Junction

32
Q

Cardiac Myocytes

A

Intercalated disks connect cardiac myocytes to each other

Components include:

Desmosomes - mechanical coupling

Fascia Adherens - Mechanical Coupling

Gap Junctions - Electrical transmission between cells - electrical coupling

33
Q

Intercalated Disc Abnormalities

A

Damage (often ischemia or inflammation) to any component of the intercalated discs can lead to heart disease

  • arrythmia
  • ventricular hypertrophy
  • Cardiomyopathy

Any of these can result in either acute or chronic heart failure

34
Q

Intestinal Epithelium

A

Enterocytes are connected by:

  • Desmosomes:
    • linking of cytoskeletons via cadherin molecules
  • Adherens Junctions (Zonula adherens):
    • Linking of cells via actin molecules
  • Gap Junctions:
    • connexins that allow small molecule exchange
  • Tight Junctions ( Zonula Occuldens):
    • Tight binding to form a ceal between celsl with selective permeability
35
Q

Enterocyte Tight Junction Abnormalities

A

Over 40 different macromolecules are identified as contributing to tight junctions

Major families of molecules include occludins, claudins, Junctional Adhesion Molecules (JAMs), and tricellulins

Pathogenic Enteric bacteria Toxins, Inflammation, or Non-inflammatory stimuli can disrupt the tight junctions

“Leaky” intestine can expose the body to intralumenal components that can cause disease

  • Loss of fluid and electrolytes
  • Systemic Bacterial invasion
  • Antigen exposure and hypersensitivities or autoimmunity
  • Metabolic disorders
36
Q

Life History of a Cell:

Aging

A

Functions of all celsl and tissues progressively decline with age

Mechanisms

  • Altered gene expression
  • Telomere shortening
  • Progressive metabolic injury
37
Q

Morphology of Aging Cells

A

Irregular Nuclei

Vacuolated mitochondria

Reduced endoplasmic reticulum

Lipofuscin

Accumulations of metabolic products

38
Q

Life History of a Cell:

Death

A

Apoptosis: Physiological Cell Death

Maintaines homeostatis in response to physiologucal and protective processes

39
Q

Apoptosis

A
  • Physiological Cell Death
    • this is the mechanism to remove damaged ot unneeded cells in the least disruptive way possible
  • Maintains homeostasis, but can also be involved in pathological states
  • Active process that requires energy from the cell
40
Q

Apoptosis:

Causes

A

Patterned death during embryogenesis

Hormone/cytokine-induced death

Maintain balance in proliferating populations

Removal of cells following completion of their purpose

Removal of self-reactive lymphocytes

41
Q

Apoptosis:

Mechanisms

A

Initiation phase:

  • extrinsic pathway
  • intrinsic pathway

Execution phase

There is considerable overlap between the pathways and multiple areas where these can be modified to influence the outcomes of the process

42
Q

Apoptosis:

Extrinsic Pathway

A

Death Receptor

Membrane receptors are activated that contain a cytoplasmic death domain

  • TNF receptor family

Fas (CD95)

Death domain activation leads to autocatalytic activation of procaspase 8

43
Q

Apoptosis:

Intrinsic Pathway

A

Mitochondrial

  • Survival factors/grwoth factors stimulate production of anti-apoptotic Bcl-2 and Bcl-x
    • maintain mitochondrial memebrane intergrity
    • Inhibit activation of apoptosis activating factor - 1
  • Loss of survival factor stimulation or injury stimulates production of pro-apoptotic Bax, Bak, and Bim
    • Loss of Bcl-2/Bcl-x increases mitochondrial permeability
    • Mitochondrial protiens leak into the cytosol
    • Cytochrome C activates Apaf-1, which then activates procaspase 9
44
Q

Apoptosis:

Morphology

A

Cell shrinkage

Condensation of cytoplasmic and nuclear components

Formation of membrane-bound vesicles

No inflammation or host response to the dead cell

45
Q

Apoptosis:

Causes

A

Pathologic Causes:

Unrepaired DNA damage

Heat

Hypoxia

Viral infection

Physical Pressure

46
Q
A

General Pathology VDMP832 (26 decks)

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