Exam 2 Flashcards
Parenchyma
Normal functioning tissue
“Resident cells” - cells that are supposed to be in that area
EX) hepatic cells in liver
Stroma
Structural framework within tissue
“Stromal”
-structure/framework of cells “scaffolding”
Fibroblasts
CT cells that form collagenous matrix
- secrete collagen
- -white fiber (protein)
- -very strong
- -supports tissue
Cell Classification (based on regenerative ability)
Labile cells
Stable cells
Permanent (fixed) cells
Labile Cells
Regenerate throughout our lifetime
EX) epithelial cells
- highly mitotic
- continuous replicators
only thing that will stop it is overcrowding
-called contact inhibition
Stable Cells
Stop dividing when growth ceases, but are capable of regeneration if properly stimulated. For these cells to regenerate properly, the underlying structural framework must be intact.
EX) liver cells
- conditional replicators
- will under mitosis ONLY if everything is intact
Permanent (fixed) Cells
Cells that are unable to divide
EX) muscle cells (heart after MI) and neurons
- NO ABILITY to undergo mitosis
- cannot replenish them
Two ways to heal injured tissue
Regeneration
- when tissue is replaced from parenchyma cells
- “best case scenario”
Repair
- when fibrous scar tissue fills in gap left by damaged tissue
- “next best thing”
Regeneration
Process in which damaged cells are replaced with parenchymal and normal structure, and normal function is restored.
2 Requirements for Regeneration
- The injury must not be too severe
- The tissue must be mitotic (labile or stable)
MUST HAVE BOTH!
Repair
When the injury is too severe OR the tissue is not mitotic, the parenchymal tissue will be replaced with fibrous connective tissue replacing structure, but sacrificing function
Revascularization
Whether healing occurs through regeneration or repair, the blood vessels in the area need to be restored. (replace blood vessels when they are lost during injury)
Angiogenesis
New capillaries formed from vessels adjacent to wound.
Dividing endothelia cells form buds or cords that extend into damaged area that eventually meet forming anastomoses
Angiogenesis
Growing new blood vessels
- normal process, happens every day
- important to growth of tumors
Healing Within the Skin
- Reepithelialization - replacement of epithelium
- New epithelial cells divide near damage
- New cells move to denuded area
- Cells secrete a new basement membrane as they migrate
- Cells then get anchored to membrane
- Dividing cells now move up towards surface of tissue
- contact inhibition tells them to stay
- overgrowth of epithliod causes large, uprised scar
Nervous Tissue Repair
Cannot Replace Neurons!
- CNS (Brain and Spinal Cord)
- PNS
CNS (nervous tissue repair)
If soma intact, some axonal regeneration may begin to occur. However, after 14 days, glial cells form scar tissue that blocks further regeneration.
No function is restored.
- neuroglial cells prevent regeneration
- could cause “rewiring” of brain
PNS (nervous tissue repair)
If soma and schwann cells are intact, axonal regeneration may occur
Factors Affecting Wound Healing
Age Nutrition Presence of infection Hormones Blood Supply Size of wound Presence of foreign bodies
Age (factors affecting wound healing)
YOUNG: increase capacity for repair, but lack reserves for repair combined with an ignorant immune system
OLD: decreased cell replacement potential, decreased immune system
Nutrition (factors affecting wound healing)
Decreased proteins and fibroblasts prolong the inflammatory phase
Fats: needed for new cell membranes
Carbohydrates: provide energy to leukocytes
Vitamins: C for collagen synthesis
Presence of Infection (factors affecting wound healing)
Impairs the healing process
- wound contamination
- impaired leukocyte function function (diabetes, certain medications)
Hormones (factors affecting wound healing)
Corticosteroids decrease capillary permeability, impair phagocytosis, and inhibit fibroblast function, all of which impairs inflammation and healing
Blood Supply (factors affecting wound healing)
Poor blood supply may result from swelling, cardiovascular disease, etc.
Oxygen necessary for collagen synthesis
Necessary to remove debris and waste
Size of Wound (factors affecting wound healing)
Suturing greatly enhances healing process
Presence of foreign bodies (factors affecting wound healing)
Wood, metal, glass, sutures
Acquired Immunity
adaptive/specific immunity
- adapts to pathogen every time it encounters one
- developed over lifetime
Specificity
Reacts to specific substances
-Antigen, Pathogen
Antigen
Molecule that elicits an IR (immune response)
ex) allergies
Epitope
Binding site on antigen
-spot on antigen that immune system can react with
Pathogen
disease causing agent
Memory
Long-term retention
encounter again = rapid response
Tolerance
Ability to distinguish between self and foreign antigens. (Self recognition)
- will attack anything that is foreign, but leave own cells alone
- very important part of immunity
Tolerance depends largely on a group of cell surface proteins known as MHC
Major Histocompatibility Complex (MHC)
Protein on surface of cell “ID tag”
*Code for making MHC is on chromosome 6
MHC is also called Human Leukocyte Antigen (HLA)
MHC Class I
Molecules found on the surface of all cells
Offer evidence of intracellular abnormalities
-acts as a billboard and gives an idea of what is going on in that cell
-important for transplants
MHC Class II
Molecules made by antigen presenting cells (APC)
Offer evidence of extracellular activities
-Macrophages - eat something and display as a trophy
Phagocytes
neutrophils and macrophages
Lymphocytes
B cells and T cells
B lymphocytes
Responsible for Humoral Immunity (Antibody Molecules)
Plasma cells: antibody synthesis
-“antibody factory” - kicks out a lot of antibodies (2000/second/cell)
Memory B: long lived immunity
-hang out and if encounter pathogen again - IR is quick
T lymphocytes
Responsible for cell mediated immunity
Produced in bone marrow and thymus: maturation occurs in thymus
-T cells learn hat they should attack and what they should leave alone
T Lymphocyte Subgroups
Helper T/CD4
Memory T
Cytotoxic
Helper T
(also called CD4)
Recognizes MHC II from APC’s
Direct the immune response via cytokine release
-“commander in chief”, “conductor”, “quarterback”
Memory T
Long term retention
-strike pathogen faster if it returns
Cytotoxic
(also called T/CD8/Killer T)
Recognizes MHC I
Destroy via perforin
- checks out cells to see if they are doing what they are supposed to
- drills holes in cell membrane
B lymphocytes (more details)
Antibody-mediated immunity (Humoral Immunity)
Create antigen specific antibodies
Maturation occurs in red bone marrow
Antibodies
Y-shaped protein molecules that provide a means for linking defenses to pathogen
-do not do destruction themselves, but plant a “kiss of death”
Have fragment of antigen binding (FAB) (variable region) that attaches to foreign epitopes.
-changes all of the time - lots of shapes
Have FC region (constant region) for single, simple binding site -doesn't attach - determines class of antibody
The antibody response to an antigen
Production of masses of antigen-specific antibodies that bind to that specific antigen
Antibodies: How they Destroy
- Attracting IS cells
- Agglutination
- Activate Complement
Attracting IS cells (antibodies)
Opsonization
- “to prepare to eat”
- hook onto anything where shapes match
- makes it easier for phagocytes to get ahold of it
Agglutination (antibodies)
Clumping
- “bigger bite” for macrophages - easier to eat
- makes it harder for pathogen to get into cells
Activate Complement (antibodies)
To form Membrane Attack Complex (MAC)
- activated in a cascade
- -end product is called MAC
- -involves 30 different proteins
- DESTROYS the cell!
Five main types/CLASSES of antibodies
IgG - immunoglobin G IgA - immunoglobin A IgM - immunoglobin M IgD - immunoglobin D IgE - immunoglobin E
IgG - immunoglobin G
Principle circulating antibody
Only one to cross placenta
Binds to macrophages
(secondary response antibody)
IgA - immunoglobin A
Secreted in saliva, breast milk, respiratory, and urogenital tract
Protects mucous membranes (from invasion)
IgM - immunoglobin M
In plasma Star Shaped (very big!)
(Primary/First antibody produced)
IgD - immunoglobin D
Found on B lymphocyte
Needed for B cell activation
(Dumb!)
(Function unknown)
IgE - immunoglobin E
Found on mast cells in allergic response
important for allergies
Long Term Immunity
First antibody response to antigen takes about a week. It peaks at about 12 days and then tapers off.
Second and subsequent challenges produce faster rise in antibody production, which is retained at higher levels for a longer time. (increases antibodies immediately)
Immune System Diseases (types)
Autoimmunities - loss of tolerance
Hypersensitivity - overreaction
Immunodeficiencies - insufficient response
Autoimmune Diseases
- Result from breakdown in the integrity of immune tolerance such that a humoral (B cell) or cellular (T cell) immune response is mounted against host cells antigens
- Etiology = idopathic
- Ability of immune system to distinguish foreign from native antigens is responsibility of MHC complexes
- Current Theories: Genetic (chromosome 6), hormonal (more women affected), environmental
Molecular Mimicry
When similarities exist between foreign and self antigens sufficient enough to trigger IR
(“mistaken identity” - antibodies attack similar shapes of own cells)
Select Autoimmune Disorders (listed)
Graves' Disease Insulin-Dependent Diabetes Mellitus Myasthenia Gravis Rheumatoid Arthritis Systematic Lupus Erythematosus (SLE) Multiple Sclerosis (MS)
Graves’ Disease
Autoantibodies bind to TSH receptors = hyperthyroidism
eyes bulge, weight loss, anxiety
Insulin-Dependent Diabetes Mellitus
Beta cell destruction
Type 1 - immune system attacks Beta cells of Pancreas - need insulin injections
Myastenia Gravis
Autoantibodies block/destroy ACh receptors
antibody hooks onto ACh receptors at neuromuscular junction; progressive muscle weakness and then paralysis
Rheumatoid Arthritis
Immune response targeting synovial membranes
Systematic Lupis Erythematosus (SLE) is also called ___ ?
nickname
“Great Imitator”
Etiology of SLE
Idiopathic
- Genetic (chromosome 6, African Americans more often)
- Environmental (UV light, sunlight, stress = increased flare ups)
- Hormonal (estrogen - more in women)
Statistics of SLE
1 in 2,500 general population
1 in 700 females
1 in 250 black females
*understand trends, not numbers
Age - women 20-40 are most affected (peak instance)