Histology Flashcards
how do myocytes & capillaries respond to HTN?
myocytes enlarge and spread capillaries apart thus reducing capillary density
All mammals have roughly the same # of myocytes regardless of heart size. So what accounts for a bigger heart?
myocyte proliferation ceases shortly after birth; the heart will continue to grow via hypertrophy
what is the function of purkinje cells & in what cardiac layer are they found in?
conduct electrical signals to the ventricles ; endocardium
In what layer are myocytes & capillaries found?
myocardium
in what layer are the autonomic ganglia found?
epicardium
In what layer are the coronary vessels found?
epicardium
RV, atria, LV: list in order of most to least amount of thickness
LV > RV > Atria
What separates the pericardium from the epicardium?
Pericardial space which is lined by mesothelium from both layers
what is the function of intercalated discs?
they join myocytes to together to synchronize contraction and allow unrestricted ionic passage through the extracellular space b/t myocytes
cardiac muscle cells have 10 times more mitochondria than skeletal muscle cells. Based on your understanding of what the mitochondrion’s role is in a cell, what can you deduce from this?
cardiac myocytes rely heavily on aerobic metabolism
adipose tissue can be found in high concentrations of what cardiac layer and why is this physiologically important?
epicardium; adipose tissue acts as cushion in pericardial cavity
The chordae Tendinae do not have a direct vascular supply so how do they get their nutrients?
circulating blood within the chambers
In which gross structures of the heart can SA nodal cells be found?
junction of SVC & right atrium
In which gross structures of the heart can AV nodal cells be found?
atrial ventricular junctions
What is the name of the fibrous structure that sends conducted electrical signals to the ventricles?
Bundle of His
The bundle of His is made up of fibers?
Cardiac endothelium that branches into subendothelial branches called purkinje fibers
SA & AV nodal cells are…..than normal myocytes while purkinje & bundles are…..
smaller; larger
BNP is produced in what gross structures of the heart?
ventricles
Histologically, how does the myocardium respond to pressure overload?
the myocardium thickens causing the diameters of the myocytes to increase which promotes chamber dilation
compared to arteries, veins have a thinner…making them more collapsible
tunica media (middle layer surrounding the artery/vein)
what structure separates the the tunica media from the tunica adventitia
external elastic membrane
the subendothelial layer of the tunica intima contains what type of tissue that allows for substance diffusion into and out cells within the deep parts of the vessel wall?
loose connective tissue (basal lamina)
large arteries have more elastic ability compared to medium arteries which are composed of what type of tissue?
muscular tissue
Where is the vasa vasorum located and what is its primary function?
tunica adventitia; supplies blood to the vessel walls
what is the main type of cell found in the tunica adventitia?
macrophages & fibroblasts
the cells in the endothelial basal lamina of the tunica intima of elastic arteries formed junctions called….
zonulae occludentes
what layers of endothelial lining is in arteries but not veins?
internal & external elastic lamina
Describe the precapillary sphincter
slight thickening of smooth muscle at origin of capillary bed and arteriole
compared to arteries & veins, capillaries only have 1 layer of endothelial cells. What does this allow for?
less resistance to fluid flow makes capillaries the main means of removing metabolic waste from the cells
compare & contrast the 3 different types of capillaries
continuous: allows for simple diffusion of small molecules like Oxygen & CO2; fenestrated have more pores and diaphragmatic capability to allow bulkier molecules through such as steroid hormones; discontinuous (sinusoids) have holes within the endothelial lining itself allowing for cells to move across different fluid compartments
What parts of the body are going to be concentrated with continuous capillaries?
muscle, lungs, & CNS
What parts of the body are going to be concentrated with fenestrated capillaries?
endocrine glands & intestines
What parts of the body are going to be concentrated with sinusoids?
liver, spleen, & bone marrow
How do endothelial cells regulate blood flow?
secrete anticoagulants, vasoconstrictors such as endothelin & ACE, & vasodilators like NO; maintenance of ECM
what parts of the body have higher concentrations of arteriovenous shunts?
thermoregulation centers near body surface
what kind of endothelium is found in postcapillary venules in lymph nodes?
cuboidal endothelium
How does histamine affect capillary beds?
increases capillary permeability
how does serotonin affect capillary beds?
increases vascular contraction
What are the primary functions of pericytes and what vessels are they located in?
postcapillary venules and some continuous capillaries; derived from same precursor cells as endothelial cells; pericytes give rise to new endothelial & smooth muscle cells during vessel growth and wound healing; they are also sensitive to NO
what is the thickest layer in medium & large veins?
tunica adventitia
Medium veins are primarily found in what part of the body & what is it about their distinctive histological features that make them well suited for where they are primarily located?
primarily found in lower extremities; in medium veins muscular tissue predominates the vessel wall making them the ideal vein for blood that has to fight against gravity to work its way back to the heart
compared to saphenous veins of the leg, would you expect venous walls in the head & UEs to be thicker or thinner
head & UEs veins will have thinner walls since they do not have to fight against gravity
Can fluid from lymphatic vessels drain back into capillary beds?
NO!!!!! fluid movement through lymphatic vessels is unidirectional
where in the body are lymphatic vessels going to be priamarily?
skin epithelium & mucous membranes
Lymph enter blood through which venous junctions?
internal jugular & subclavian
What is the main and largest lymphatic duct in the body?
thoracic duct
lymphatic vessels have greater permeability than blood capillaries. What is the physiological significance of this?
lymphatic vessels are more effective at removing protein & lipid rich fluid for ICF
before lymph can be returned to the blood, it has to stop at an important checkpoint? what is the name of this checkpoint?
the lymph nodes which are rich with white blood cells
