Week 2 Stress&Adaptation/ Neoplasia/ Tissue Repair&Wound Healing

Patho 500

Homeostais

body maintaining a stable balanced environment

Negative Feedback

monitored function / value decreases below the set point, feedback mechanism causes to increase ; also happens in reverse

General Adaptation Syndrome

Neuroendocrine response (to stress)

Immune System (in response to stress)

Immune cells (lymphocytes) send messages to the brain (cytokines) through the blood brain barrier to complete a stress response

how are the nervous and immune systems linked?

Nerves from the autonomous nervous system supply immune organs (lymph nodes/thymus/spleen) through inhibition of catecholamines and cortisol

process may lead to illness!

Acute Stress response

“fight or flight” short term response

alertness, vigilance from physiological or psychological stressors

Chronic Stress Response

prolonged stress that overwhelms the feedback system

leads to chronic or long term health problems such as PTSD

Adaptation to Stress

ability for the body to respond to challenges of physical or psychological homeostasis return to a balanced state

what is tissue repair

process that restores structure and function after healing

goal: restore look, structure and strength

tissue repair occurs through…

regeneration- replacement with original cells

fibrous tissue repair- replacement with scar tissue (collagen)

Regeneration

same type of cells replace injured ones

occurs in labile and stable tissues such as the skin or liver

fibrous repair

scar tissue replaces injured cells

occurs when tissue cannot regenerate (w the same cells)

ex such as when an MI occurs

scars limit organ function

Regulations on Healing

controlled by growth factors, cytokines, and ECM

depends on cell proliferation, migration and differentiation

key: PDGF & TGF-Beta

Local Factors of Wound Healing

response to tissue injury

1. Homeostasis

2. Inflammation

3. Proliferation

4. Remodeling

Healing Types (Wound Healing)

Primary Intention and Secondary Intention

Primary Intention

edges of wound are well-approximated

-minimal tissue loss

-clean incision

-quick healing

-small scar

ie. surgical wounds

Secondary Intention

open wounds that are not approximated

-large tissue loss

-slower healing

-large scar

ie burns or ulcer

Inflammatory Phase

Proliferation Phase

Wound Contraction & Remodeling

takes weeks to months

Myofibroblasts contract the wound

Collagen Type 3 → Type 1

strength increases

final tissue is ~80% Strength

Local Factors that affect wound healing

infection

blood supply

moisture

Systemic factors of wound healing

age

diabetes

nutrition

corticosteroids

smoking

Clinical Manifestations of Poor Healing

persistent inflammation

non-healing edges

purulent drainage

keloids

wound dehiscence

chronic pain

Neoplasia

Tumors

growth of new, uncontrollable cells

Tumor

mass of cells due to overgrowth

can be defined as Malignant or Benign

adding the suffix -oma to the parenchymal tissue type from which the growth originated

Adenoma

benign tumor of glandular epithelial tissue

Adenocarcinoma

malignant tumor of glandular epithelia tissue

Carcinoma

malignant tumor of epithelia tissue

osteoma

benign tissue of bone tissue

sarcoma

malignant tumors of mesenchymal origin

Papillomas

benign microscopic or macroscopic finger-like projections growing on a surface

Benign Neoplasms

slow and do not spread - may standstill or regress

cannot invade surrounding tissues

Malignant Neoplasms

grow fast and have potential to kill no matter their original location

take essential nutrients from normal tissues

destroy normal tissue

Factors differentiating benign and malignant neoplasms

cell characteristics

manner of growth

rate of growth

potential for metastasizing or spreading

tendency to cause tissue damage

capacity to cause death

Anaplasia

describes the loss of cell differentiation in cancerous tissue

undifferentiated cells are marked by different morphologic changes, such as size, shape or condition

pleomorphism

undifferentiated cell changes in size or shape

Methods by which cancer spreads

direct invasion and extension

seeding of cancer cells in body cavities

metastatic spread through the blood or lymph pathways

Factors affecting tumor growth

number of cells dividing or moving

length of cell cycle

number of cells lost vs new cell production

growth fraction (ratio of dividing cells to resting cells in a tissue mass)

doubling time- time it takes for mass of cells in a tumor to double

genes that control cell growth and replication

protooncogenes genes

tumor supressor genes

geenes that control programmed cell death or apoptosis

genes that regulate repair of damaged dna

Initiation of Cancer cell formation

cells exposed to doses of carcinogenic agents making them susceptible to malignant transformation

Promotion of Cancer cell formation

unregulated accelerated growth in already initiated cells caused by chemicals and growth factors

Progression of cancer cell formation

where cells get more mutations and allows them to invade, metastasize and resist control mechanisms

Factors leading to cancer

Heredity - hormones, carcinogens, chemicals, radiation, viruses

Immunologic- stem cells, angiocentesis, microenvironmental effects

Clinical Manifestations of Cancer

tissue integrity

cancer cachexia - weight loss of body fat / tissues / anorexia / anemia

paraneoplastic syndromes - innapropriate hormone release or other circulation issues