SM02 Mini1 Flashcards
function of aorta
maintain blood pressure
function of arteries
distribute blood to & w/in organs
function of arterioles
control flow w/in organs
function of capillaries
metabolic exhange
function of veins & vena cava
buffer blood volume
return blood to heart
tunica initima
single layer of endothelial cells sitting on a basal lamina
**only layer found in capillaries
may contain subendothelial connective tissue of loose connective tissue & scattered smooth muscle cells in larger vessels
tunica media
middle layer composed of mostly smooth muscle cells
**contraction of these cells regulates blood pressure**
also contains elastic fibers, type II collagen, & proteoglycans
tunica adventitia
outer layer of blood vessels
composed mostly of fibroblasts, type I collagen fibers, & longitudinally oriented elastic fbers
continuous w/connective tissue of surrounding elements
vasa vasorum
found in tunica adventita & outer part of media of large vessels
supply blood to outer 1/2 of vascular walls
what are the elastic arteries and what makes them elastic?
biggest arteries: aorta, major branches, & pulmonary arteries
tunica media is formed by intercalated layers of smooth muscle & elastic laminas
why do elastic arteries need to be elastic?
to handle high pressure
Windkessel effect
recoil of distended elastic arteries serve to maintain arterial pressure & flow of blood thru tissues
why are holes present in the elastic lamellae of elastic arteries?
to allow nutrients/O2 to diffuse
allow processes of smooth muscle cells to contact each other across layers to facilitate synchronised contractions
how are the elastic & collagen fibers formed in the tunica media of elastic arteries?
they are synthesized by muscle cells NOT fibroblast as in connective tissue
what cells are used to repair the tunica intima?
tunica media smooth muscle cells in response to the appropriate growth factors from endothelial cells
mechanism of an aortic dissection
- tear in tunica intima
- blood surges into tear separating tunica intima & tunica media
- dissection may then tear aorta completely open→ rapid blood loss→ death
susceptibilies to aortic dissection
chronic HTN creating stress on aortic tissue
Marfan’s syndrome (mutation in fibrillin- major component of elastic fibers) or other connective tissue disorders
defining characteristics for muscular arteries
tunica media dominated by smooth muscle cells
internal elastic lamina/membrane separating tunica intima & tunica media, composed of elastin
larger muscular arteries even have an external elastic lamina between tunica media & adventitia
characteristics of arterioles
no external elastic lamina
very small also do not have internal elastic lamina
media is only 1-2 layers of smooth muscle
very thin tunica adventitia
characteristics of metarterioles
branch from arterioles
discontinuous layer of smooth muscle
where is the smooth muscle found in veins?
tunica adventitia
used to help move blood along
as opposed to arteries where it is in the tunica media
major distinguishing factor between veins & arteries of the same size?
veins will have much smaller tunica media & larger lumen
what are venous valves made of?
tunica intima jutting out into the lumen reinforced w/collagen & elastic fibers
why do deep vein thromboses form when people are immobile?
because the skeletal muscle pump is inactive allowing local coagulation or clotting of blood
how do varicose veins form?
valves fail to close properly
blood pools in vein until it forces vein walls outward→ enlargement & bulging of vein
how is blood flow into the capillaries regulated?
contraction & relaxation of smooth muscle rings in arterioles/metarterioles
only 3-5% of capillaries open to maximal blod flow at any one time due to switching
why is capillary flow so highly regulated?
temperature regulation
control of blood loss
regulation of nutrients
what are the types of capillaries?
continuous
fenestrated
discontinuous/sinusoidal
where are pericytes found & what is their function?
basal lamina of pericytes is continuous w/basal lamina of capillaries
functions:
- take place of tunica media contractin to help move blood thru capillaries & post-capillary venules
- growth & regeneration of injured blood vessels
characterization of continuous capillaries
continuous layer of endothelial cells attached via tight junctions
w/continuous basal lamina
numerous pintocytotic vesicles transport large macromolecules in BOTH directions (EXCEPT in nervous tissue)
where are continuous capillaries found in the body?
muscle tissue, connective tissue, exocrine glands, & nervous tissue
characterization of fenestrated capillaries
presence of fenestrae/pores in endothelial wall
more permeable to water & small solutes
pores are bridged by ultrathin diaphragm
CONTINUOUS basal lamina
where in the body are fenestrated capillaries found?
places of rapid interchange of substances between tissue & blood
intestines
endocrine glands
kidneys (those in glomerulus lack diaphragm for rapid filtration)
characterization of sinusoidal capillaries
aka discontinuous capillaries
fenestrated w/no diaphragms AND discontinuous endothelial cells (no tight junctions)
discontinuous basal lamina
tortuous path→ slow blood flow
irregular blood pools or channels that conform to shape of structure where they are located
where in the body are sinusoidal capillaries found?
specialized for maximal molecular exchange & easy movement of blood cells across endothelium
liver
heatopoietic organs: bone marrow & spleen
what substances are & are not allowed thru the BBB?
blood-brain barrier
essential metabolites (oxygen & glucose) are allowed thru
blocks most molecules >500Daltons
How is the BBB so limiting?
extensive endothelial tight junctions
very few pintocytotic vesicles (most only take up- ex. LDL)
how is the BBB formed?
during early embryonic development
astrocytes secrete factors to induce capillary endothelial cells to form extensive tight junctions
arteriovenous anastomosis
direct communication between arterioles & venules
capillaries are bypassed
arterial portal system
present in kidney glomerulus
arteriole→capillary→arteriole
venous portal system
used in the liver
venule→ capillary→ venule
what layer of the heart is the tunica intima of connecting blood vessels continuous with?
endocardium
what forms the endocardium?
endothelium of connective tissue lined w/simple squamous endothelial cells
subendocardial layer or variable thickness made of dense connective tissue & contains small blood vessel, nerves, and Purkinje fibers
how are the muscle cells of the myocardium arranged?
in complex spirals around orifices of chambers
bundles course in different directions & are separated by loose connective tissue
what forms the epicardium?
fibrous connective tissue covered by thin mesothelium
subepicardial layer of loose connective tissue contains coronary vessels, nerves, ganglia, & fat
how are the heart valves anchored?
by a fibrous skeleton of dense connective tissue w/in the endocardium
what happens when cardiac tissue dies?
does not regenerate
replaced by fibrous connective tissue
why do Purkinje fibers stain lighter around the nuclei?
local acculumation of glycogen
atherosclerosis
buildup of fats, cholesterol, & other substances in & on artery walls (forming plaques)
describe evolution of atherosclerotic plaque.
- endothelial cells damaged
- due to HTN, smoking, toxins, & other agents
- monocytes migrate to site of damage
- monocytes differentiate into macrophages
- macrophages take up excess lipid becoming foam cells
- foam cells release growth factors & cytokines that act on smooth muscle cells (SMCs)
- SMCs react by migrating into intima & surround foam cells
- SMCs assume synthetic phenotype
- produce collagen & fibronectin forming a cap under endothelial cells
major risk factors for atherosclerosis
- hyperlipidemia
- smoking
- HTN
- turbulence (as seen in atrial fibrillation)
what cell type(s) form foam cells?
- macrophages
- smooth muscle cells (of tunica media)
how does smoking promote atherosclerosis?
production of carbon monoxide damages endothelial cells
may promote oxidation of LDL
describe structure of lymphatic capillaries
overlapping free borders of endothelial cells
discontinuous basal lamina
attachment of anchoring fibrils: elastic fiber system that holds lymphatic capillaries open & anchors to surrounding connective tissue
describe pathway of air thru all structures to alveoli.
- conducting portion
- nasal cavity
- pharynx
- larynx
- trachea
- bronchi
- bronchioles
- terminal bronchioles
- repiratory portion
- respiratory bronchioles
- alveolar ducts
- alveolar sacs
- alveoli
describe the external vestible of the nasal cavity
- most anterior part of nose, includes ala
- contains vibrisse: short stiffu hairs that filter dust
- stratified squamous epithelium
- lots of sebaceous & sweat glands in dermis
- dermis anchored to hyaline cartilage of ala
what type of epithelium is found in the nasal fossa?
pseudostratified ciliated columnar epithelium w/goblet cells
aka respiratory epithelium
how is the air warmed in the nasal fossa?
by the extensive arterial plexuses
what structures create a vortex to warm, moisten, and clean air in the nasal fossa?
nasal conchae or turbinates
what are swell bodies & where are they found?
large venous sinuses in the respiratory epithelium of the inferior & middle nasal conchae
what is the difference between the superior nasal concha & the other two?
- covered by olfactory mucosa
- lined with pseudostratified columnar epithelium
- no goblet cells
- no cilia
where is olfactory mucosa found?
roof of nasal cavity
superior region of nasal septum
superior nasal concha
what cell types are found in olfactory mucosa?
olfactory
sustentacular
basal
why are the cilia of olfactory receptor cells nonmotile?
they lack dynein arms
describe the structure of an olfactory receptor cell.
- bipolar neuron
- olfactory vesicle forms at spical dendritic end w/6-8 long nonmotile cilia attached
- basal end form unmyelinated axon
- axons join together to form olfactory nerve
- life span= 3 months
how many scents can each olfactory cell detect?
ONE
olfactory cilia of a cell has numerous copies of one particular odor receptor molecule
what is the function of sustentacular cells?
- physical support for olfactory cells
- metabolic support via secretion of odorant-binding proteins to olfactory cells
describe the structure of sustentacular cells.
- tall columnar w/apical microvilli
- ovoid nucleus in apicla third of cell
- apical secretory granules contain olfactory mucus
what is the function of basal cells in the olfactory mucosa?
mitotic reservoir
can differentiate into olfactory or sustentacular cells
what type of gland & its secretion are found in the lamina propria of olfactory mucosa?
Bowman’s gland
serous secretions
trap & solvent odoriferous substances for detection & constant flow clears them away
where does the nasal cilia sweep mucus towards?
paranasal sinuses
what type of epithelium lines each section of the pharynx?
- superior nasopharynx: ciliated pseudostratified columnar epithelium w/goblet cells
- middle oropharynx: stratified non-keratinized squamous epithelium
- inferior laryngopharynx: stratified non-keratinized squamous epithelium
lamina propria is dense irregular connective tissue w/seromucous glands
functions of larynx
phonation
prevent entry of food & fluids into respiratory system
what type of epithelia lines the epiglottis?
- anterior, apex, & 1/2 of posterior side
- lingual mucosa= stratified squamous nonkeratinized epithelium
- postior/laryngeal surface
- respiratory= pseudostratified ciliated columnar epithelium w/goblet cells
where is stratified squamous nonkeratinized epithelium found in the larynx?
inferiorly on vocal cords
superior/anterior surface, apex, & 1/2 posterior surface of epiglottis
what forms the vocal ligament?
large bundles of parallel elastic fibers in dense connective tissue of lamina propria of vocal cords
what types of tissue comprises the submucosa of teh trachea?
dense irregular fibroelastic connective tissue
w/numerous seromucous glands
where are lymphocytes found in the trachea?
lamina propria of mucosal layer
what surrounds teh submucosa of the trachea?
adventitia
composed of fibroelastic connective tissue
houses hyaline cartilage C-shaped rings (16-20) & trachealis smooth muscle between rings
do all cells of respiratory epithelium reach the lumen?
no, but they all touch the thick basement membrane
Name the cell types found in respiratory epithelium
- goblet cells
- ciliated columnnar cells
- basal cells
- brush cells
- serous cells
- diffuse neuroendocrine system (DNES) cells
what are cilia made of?
microtubules
what are microvilli made of?
actin
what is the function of goblet cells?
secrete mucus on surface of epithelium
what is the function of ciliated columnar cells?
move/beat mucus and any trapped matter up & out of respiratory tract toward nasopharynx
what is the function of basal cells in respiratory epithelium?
stem cells to replace goblet cells, ciliated columnar cells, or brush cells
**short & do not reach luminal surface
what is the function of brush cells?
tall microvili on apical surface of columnar have sensory role
what is the function of serous cells in respiratory epithelium?
unknown
they are columnar w/apical microvilli
what is the function of DNES cells?
small graular cells that secrete catecholamines
besides mucins and trapped particles, what else is in mucus?
immunoglobulins
lysozymes (have antibacterial properties)
antiproteases (disable bacterial function)
as the amount of cartilage decreases, what happens to amt of: glands, goblet cells, height of epithelial cells, smooth muscle, elastic tissue?
- decrease in # of glands
- decrease in # of goblet cells
- decrease in columnar cell height
- increase in smooth muscle in respect to wall thickness
- increase in elastic tissue in respect to wall thickness
describe structure of intrapulmonary bronchi.
- respiratory epithelium
- irregular hyaline cartilage plates
- 2 smooth muscle layers spiral in opposite directions
- increase of elastic fibers in adventitia & submucosa
- seromucous glands in lamina propria
what are Clara cells?
dome-shaped columnar cells w/short microvilli
secretes surface active protein→ prevents luminal adhesion if airway collapses
degrade toxins via cytochrome P450 in SER
divide & differentiation in to ciliated & nonciliated epithelial cells
how does the epithelia change as bronchioles decrease in size?
decrease # of ciliated cells (single columnar instead of pseudostratified)
increase # of Clara cells
what is the key difference in epithelia of terminal bronchioles?
epithelial cells become simple cuboidal in shape
how are smooth muscle fibers arranged in bronchioles?
in concentric spirals
how are elastic fibers arranged in bronchioles?
longitudinally
what type of epithelium is in the respiratory bronchioles?
ciliated & non-ciliated cuboidal cells w/Clara cells
interrupted by alveoli
what type of epithelium is found in the alveoli?
simple squamous
what controls the openin of each alveolus to alveolar duct?
single smooth muscle cell embedded in collagen type II
what is the interalveolar septum and its composition?
alveolar wall between 2 alveoli
reticular fibers (collagen type III), elastic fibers, continuous capillaries, & macrophages
what is the function of alveolar pores?
connect adjacent alveoli to equalize pressure
what is the function of type I pneumocytes?
gas exchange
describe the structure of the type I pneumocytes.
- simple squamous cells
- thin cytoplasm
- organelles close to nucleus
- form occluding junctions w/each other→ prevent leaking of extracellular fluid into alveolar lumen
- luminal surface lined by surfactant
**95% of alveolar surface area**
which are more numerous: type I or type II pneumocytes?
type II
which cover more surface area: type I or type II pneumocytes?
type I
what is the function of type II pneumocytes?
produce & phagocytose surfactant
undergo mitosis to regenerate type I & type II pneumocytes
describe appearance of type II pneumocytes.
cuboidal
form occluding junctions w/adjacent cells (type I)
interspersed among type I pneumocytes
presence of Lamellar bodies→ secrete surfactant
Name the layers of the blood-gas barrier.
- type I pneuomocyte coated in surfactant
- basal lamina of alveolar epithelium
- basal lamina of capillary endothelium
- endothelial cells of continuous capillary
2 & 3 are fused
what causes respiratory distress syndrome?
no surfactant or inadequate amounts
seen in infants born before 7 months
how is respiratory distress syndrome treated?
- synthetic surfactant
- acts immediately to reduce surface tension
- replaces surfactant
- glucocorticoids
- stimulates type II pneumocyte to produce surfactant
describe the pathological progression of emphysema.
- long-term smoking/exposure
- inhibits alpha-1 antitrypsin
- normally prevents destruction of elastic fibers in lungs via elastase
- elastase produced by alveolar macrophages
- normally prevents destruction of elastic fibers in lungs via elastase
- reduced elasticity of lungs & large fluid filled spaces→ decrease in gas exchange capability
what is the cause of an asthma attack?
bronchiolar smooth muscle prolonged contraction during expiration
difficulty expelling air
