Pathophysiology Exam 2

arteries

transport high pressure blood, maintain blood pressure

arterioles

slightly smaller than arteries; exhibit large changes in diameter = resistance vessels

capillaries

smallest vessels, used for exchange

venules

small veins; collection of blood from capillary beds

capillary beds

interwoven connection network between arterioles, venules and main blood flow

veins

return low pressure blood to the heart

blood vessel layers

adventitia, tunica media, tunic intima

adventitia

outer layer; structural support, gives shape to the vessel

tunica media

middle layer; elastic, muscular tissue, regulates internal diameter of vessel

tunic intima

inner layer; endothelial lining provides frictionless pathway for blood movement

capillary layers

single layer of flattened endothelial cells, no muscular or adventitial layers

why are capillaries so thin

helps efficient exchange between lumen of capillaries and surrounding tissue

smaller the vessel

less elastic tissue and smooth muscle cells increase

segmentation of blood vessels

elastic artery, muscular artery, arteriole, capillary, small venule, large venule, vein

movement from arteries to veins

tunic intima remains the same, tunica media decreases in size, adventitia increases in size

movement from arteries to veins in the liver, spleen, and bone marrow

blood flows from arterioles to sinusoids to venules

what are sinusoids

incomplete basement membrane

capillary types

true capillaries, thoroughfare channels, metarteriole channels

true capillaries

blood flows from arterioles into capillaries and then into venules

thoroughfare channels

shunt that allows blood to bypass true capillaries; low pressure; capillary exchange not required

metarteriole channel

smooth muscle channel that connects arteriole to venule; regulate and direct red blood cells into true capillaries; exchange vessel

what vessels make up the microcirculation

arterioles, capillaries, venules

what is the main function of microcirculation

oxygen transfer from RBCs in capillaries to parenchymal cells

what do lymphatic capillaries do

carry extravascular fluid into the venous system

what is perfusion

blood supply to tissues via capillaries

what occurs at capillaries

exchange of gases, nutrients, water, wastes, hormones

what are the three types of capillaries

continous, fenestrated, sinsoidal

structure of continous capillaries

uniterrupted endothelial lining with tight junctions

where are continuous capillaries found

muscle, lung, skin, gonads, CNS

what barrier do they form in the CNS

blood-brain barrier

what defines fenestrated capillaries

small pores (fenestrae) for filtration/transport

where are fenestrated capillaries found

endocrine glands, kidney (glomerulus), small intestine, gallbladder

what defines sinusoidal capillaries

discontinuous endothelium with large pores

where are sinusoidal capillaries found

liver, spleen, bone marrow, lymphoid organs

what are the two specialized capillary systems

glomerulus and portal systems

what is the glomerulus

capillary network for filtration; drains into efferent arteriole, leads to vasa recta

what is the portal system

capillary bed, vein, second capillary bed (no heart in between)

what does the hepatic portal system do

sends GI/spleen blood to liver for nutrient processing and detoxification

what is sepsis

life-threating systemic inflammatory response to infection

what causes capillary leakage in sepsis

cytokines to vasodilation and increased permeabilityk

key symptoms of sepsis

fever/shivering, confusion, rapid breathing, pain, clammy skin

what is septic shock

sepsis + persistent hypotension requiring vasopressors

main functions of the lymphatic system

immune defense and drainage of excess interstitial fluid

what is chyle

fat rich lymph from intestinal lacteals

primary lymphoid organs

bone marrow (B cells), thymus (T cells)

secondary lymphoid organs

lymph nodes, spleen, MALT

what is MALT

lymphoid tissue in mucosae

what is lymphedema

chronic accumulation of protein-rich lymph causing swelling

primary vs secondary lymphedema

primary- congenital mutation; secondary- obstruction/damage (e.g., filariasis, cancer)

treatment for lymphedema

compression, exercise, massage, decongestive therapy, surgery

how is lymphatic filariasis transmitted

mosquito bites delivering larval parasites

how do larval parasites cause lymphatic filariasis

adult worms block lymphatic drainage which leads to severe swelling/elephantiasis

what is the fundemental cause of cell injury

perturbation of homeostasis

list the major mechanisms of cell injury

decreased ATP, mitochondrial damage, increased calcium entry, increased reactive oxygen species, membrane damage, DNA/protein damage

what happens when ATP is deleted

Na+/K+ pump failure which leads to swelling; increased anaerobic glycolysis; increased lactic acid; decreased protein synthesis; Ca2+ pump failure

what does mitochondrial damage cause

increased permeability, decreased oxidative phosphorylation, increased reactive oxidative species, leakage of cytochrome C, which leads to apoptosis

what does excess intracellular calcium activate

enzyme that damage membranes, proteins, and DNA

what do reactive oxidative species damage

lipids, proteins, and nucleic acids

define hypoxia

oxygen deficiency due to respiratory failure, anemia, carbon monoxide poisioning

define ischemia

reduced blood supply from arterial blockage or poor venous drainage

list other causes of cell injury

physical agents, chemical/drugs, microbes, immune reactions, genetic defects, nutritional imbalance, aging

key features of reversible injury

membrane blebbing, mitochondrial swelling, ER dilation, ribosome detachment, chromatin clumping (nucleus intact)

key features of irreversible injury

breakdown of plasma membrane, organelles, and nucleus; leakage of cellular contents

apoptosis defintion

regulated cell death; cell shrinkage, chromatin condensation, apoptotic bodies; no inflammation

pyroptosis definition

imflammatory programmed death, swelling, membrane rupture, cytokine release; nucleus intact

necrosis definition

uncontrolled death from severe injury; swelling membrane rupture, inflammation

necroptosis

regulated necrosis; resembles cecrosis but uses programmed signaling

autophagy definition

self-digestion via autophagosomes; survival mechanism; excessive autophagy leads to cell death

what is hypertrophy

increased cell size which leads to increased organ size; no increase in cell number

what is hyperplasia

increased cell number, reversible, occurs in stable tissues

atrophy definition

decreased cell size and/or number due to decreased nutrients, blood flow, or hormone secretion

metaplasia definition

reversible change of one differentiated cell type to another better suited to stress

dysplasia definition

disordered, abnormal cell growth; reversible early; risk of neoplasia

dry gangrene cause

chronic ischemia, tissue becomes dry, dark, shriveled; may autoamputate

wet gangrene cause

infection + necrosis; swollen, painful, foul smelling; rapid progression

gas gangrene cause

clostridium infection; gas production, severe pain, rapid spread; life-threatening

autoamputation defintion

spontaneous detachment of necrotic tissue without surgery

what happens during ischemia

decreased ATP, pump failure, Na+/H2O influx, swelling; calcium overload; membrane damage

why is reprofusion harmful

sudden reactive oxidative species burst, Ca2+ overload, mitochondrial pore opening, inflammation

what regulates blood flow into the microvascular bed

contraction of precapillary sphincters controls blood entry into true capillaries

what is an arteriovenous shunt

a direct connection between arterioles and postcapillary venules that bypasses microcirculation

define innate immunity

non specific, immediate defense present at birth; includes barriers, phagocytosis, inflammation, fever

define adaptive immunity

antigen specific, learned immunity that develops memory and takes days to activate

what are the two branches of adaptive immunity

humoral (B cells, antibodies) and cell-mediated (T cells, cytotoxic response)

neutrophil function

first responders; phagocytose bacteria and rise in number during illness

eosinophil function

release granules to kill pathogens; involved in parasite defense and cytokine production

basophil function

release histamine; participate in inflammatory responses and T-helper cell maturation

monocyte function

circulating phagocytes that become macrophages or dendritic cells in tissues

mast cell functions

release histamine and heprin; involved in wound healing and parasite elimination

NK cell function

cytotoxic lymphocytes that kill virus-infected and cancer cells using perforins and granzymes

what triggers inflammation

tissue damage, leads to mast cells and basophils release histamine, increasing vasodilation and permeability

what are the 5 cardinal signs of inflammation

redness, heat, swelling, pain, loss of function

cause of redness

vasodilation leads to increased blood flow

cause of swelling

increased vascular permeability, leads to fluid leakage into tissues

define acute inflammation

rapid onset, short duration; dominated by neutrophils; examples: cellulitis, pneumonia

define chronic inflammation

long term (months - years); dominated my mononuclear cells, fibrosis, tissue destruction

possible outcomes of acute inflammation

resolution, fibrosis/scar, chronic inflammation, abcess formation

list the steps of neutrophil migration

margination to rolling to adhesion to emigration (diapedesis)

what molecules mediate rolling

selectins on endothelium

what molecules mediate adhesion

integrins binding to ICAM-1