Term
| what does the mediastinum contain? |
|
Definition
| all thoracic viscera, except the lungs |
|
|
Term
| describe features of the mediastinum |
|
Definition
| central compartment of the thoracic cavity; surrounded by the pleural cavities; extends from the superior thoracic aperture to the diaphragm; highly mobile in the living; with age, connective tissue becomes more fibrous and rigid |
|
|
Term
| the transverse thoracic plane is drawn between what regions? |
|
Definition
| drawn from the sternal angle to the IV disk between the T4 and T5 vertebrae |
|
|
Term
| in the supine position, is the aortic arch transected by the transverse thoracic plane? |
|
Definition
| no; it is superior to the plane |
|
|
Term
| in the supine position, the central tendon of diaphragm lies at the level of what vertebrae? |
|
Definition
| T9; the xiphisternal junction |
|
|
Term
| in the supine position, is the tracheal bifurcation transected by the transverse thoracic plane? |
|
Definition
|
|
Term
| in the standing position, is the aortic arch transected by the transverse thoracic plane? |
|
Definition
|
|
Term
| in the standing position, where may the central tendon of diaphragm fall to? |
|
Definition
| may fall to the mid level of xiphoid process (disc between T9-T10); initially was at the level of the xiphisternal junction (T9) in the supine position |
|
|
Term
| what can be found in the superior mediastinum? |
|
Definition
Superior vena cava
Brachiocephalic veins
Arch of aorta
Thoracic duct
Trachea
Esophagus
Thymus
Left recurrent laryngeal nerve |
|
|
Term
| what can be found in the anterior mediastinum? |
|
Definition
Remnants of thymus
Lymph nodes
Fat & connective tissue |
|
|
Term
| what can be found in the middle mediastinum? |
|
Definition
Pericardium
Phrenic nerves
Heart & cardiac plexus
Roots of great vessels
Arch of azygos vein
Main bronchi & tracheobronchial lymph nodes |
|
|
Term
| what can be found in the posterior mediastinum? |
|
Definition
Esophagus
Thoracic aorta
Azygos & hemiazygos veins
Thoracic duct
Vagus nerves
Sympathetic trunks
Splanchnic nerves |
|
|
Term
| the left ventricle is located in which auscultatory area? |
|
Definition
| under the 5th intercostal space |
|
|
Term
| are you able to remove the visceral pleura from the lung? |
|
Definition
|
|
Term
| what is the heart surrounded by? |
|
Definition
|
|
Term
| what transverses the space that exists between the pericardial sac and the pleura? |
|
Definition
| pericardiacophrenic arteries and the phrenic nerve |
|
|
Term
| describe the pericardium and its characteristics |
|
Definition
The pericardium has an outer fibrous & an inner serous portion
Fibrous pericardium is continuous with the pretrachial layer of cervical fascia, tunica adventicia of the great vessels, sternum, diaphragm, and loosely to structures in the post. Mediastinum
The inner serous layer is invaginated by the developing heart & becomes a double layer forming a visceral & parietal serous layer
The space between the two layers of serous pericardium is the pericardial cavity |
|
|
Term
| where is the transverse pericardial sinus located? |
|
Definition
| anterior to the superior vena cava and posterior to the aorta and the pulmonary trunk; important in heart surgery |
|
|
Term
| what is the main blood supply to the pericardium? |
|
Definition
via the pericardiacophrenic artery, a branch of the internal thoracic artery; minor contributors are:
musculophrenic artery, a terminal branch of the internal thoracic artery
Coronary arteries (only visceral layer of serous pericardium)
Branches of the thoracic aorta |
|
|
Term
| venous drainage of the pericardium is mainly via which veins? |
|
Definition
| pericardiacophrenic veins to the brachiocephalic veins; the azygous system of veins also has tributaries |
|
|
Term
| what nerves innervate the pericardium? |
|
Definition
the phrenic nerves (C3-C5)
minor contributors are:
vagus nerve (function uncertain)
sympathetic trunks (vasomotor) |
|
|
Term
| what type of nerves are the phrenic nerves? (somatic or visceral) |
|
Definition
|
|
Term
| describe the relationship of the phrenic nerve to the root of the lung in the middle mediastinum |
|
Definition
| the phrenic nerve passes anterior to the root of the lung |
|
|
Term
| describe the relationship of the vagus nerve to the root of the lung in the middle mediastinum |
|
Definition
| the vagus nerve passes posterior |
|
|
Term
| describe the relationship of the pericardiacophrenic vessels and phrenic nerves to the fibrous pericardium in the middle mediastinum |
|
Definition
| The pericardiacophrenic vessels & the phrenic nerves lie within or superficial to the fibrous pericardium |
|
|
Term
| when you approach the heart from the anterior side, most of what you will see will be the _____ ventricle |
|
Definition
|
|
Term
| the sternocostal surface of the heart is formed mostly by which structures? |
|
Definition
| Formed mostly by right ventricle & small part of right atrium |
|
|
Term
| the diaphragmatic surface of the heart is formed mostly by what structures? |
|
Definition
| Formed mostly by left ventricle & small part of right ventricle |
|
|
Term
| the base or posterior surface of the heart is formed mainly by what structures? |
|
Definition
Formed primarily by the left atrium & a small part of the right atrium
It lies anterior to the esophagus – anterior ulceration can erode into the left atrium |
|
|
Term
| what is the function of the crista terminalis? |
|
Definition
| separates the smooth from the rough walls of the atrium |
|
|
Term
| what region does the sulcus terminalis mark? |
|
Definition
|
|
Term
| is the fossa ovalis closed in everyone? |
|
Definition
| can remain open in some people and can cause no problems |
|
|
Term
| which layer is the endocardium? (innermost, middle, or outermost) |
|
Definition
|
|
Term
| which layer is the myocardium? (innermost, middle, outermost) |
|
Definition
|
|
Term
| which layer is the epicardium? (innermost, middle, outermost) |
|
Definition
|
|
Term
| what type of epithelium is the tunica intima? |
|
Definition
| simple squamous (endothelium) |
|
|
Term
| describe the tunica intima |
|
Definition
Closest to the lumen.
simple squamous epithelium (endothelium)
contacts the blood.
Beneath the endothelium is a subendothelial layer
variable thickness
composed of loose connective tissue containing some smooth muscle cells.
Endothelium and elements of the subendothelium oriented longitudinally, i.e. in the same axis as blood flow. |
|
|
Term
| what are the 7 functions of the endothelium? |
|
Definition
Maintains selective permeability barrier.
Maintains non-thrombogenic barrier.
Modulates blood flow and vascular resistance.
Regulates cell growth.
Regulates immune response.
Maintains ECM.
Involved in lipoprotein metabolism |
|
|
Term
| what is the most prominent layer in arteries? |
|
Definition
|
|
Term
| in arteries, what separates the tunica media from the tunica intima? |
|
Definition
|
|
Term
| all the ECM in the tunica media are synthesized by which type of cells? |
|
Definition
|
|
Term
| describe the tunica media in arteries |
|
Definition
MOST PROMINENT LAYER IN ARTERIES
concentric layers of smooth muscle and elastic membranes.
relative amounts of smooth muscle and elastic membranes dependent on type of vessel.
In arteries, media separated from intima by internal elastic lamina.
Reticular fibers (Type III collagen) and proteoglycans found in the media,
In elastic arteries elastic lamellae predominate.
All ECM in the media is synthesized by smooth muscle cells.
Elements of media circularly arranged |
|
|
Term
| what is the most prominent layer in veins? |
|
Definition
|
|
Term
| describe the tunica adventitia |
|
Definition
MOST PROMINENT LAYER IN VEINS
connective tissue sheath
contains mainly type I collagen
Also, elastic fibers, and smooth muscle (number depends on type of vessel).
In large vessels may have blood vessels (vasa vasorum)
vasomotor nerves (nervi vascularis) form a network in the adventitia
Innervate smooth muscle of media
Elements of adventitia longitudinally arranged |
|
|
Term
| what are the 3 distinct layers of the heart? |
|
Definition
| endocardium, myocardium, epicardium |
|
|
Term
| describe the endocardium layer of the heart |
|
Definition
Innermost - homologous to the tunica intima.
Composed of an endothelial lining with an underlying subendocardium.
Subendocardium composed of loose connective tissue containing elastic and collagen fibers as well as some smooth muscle cells.
Subendocardium contains some small veins, nerves and in some locations, Purkinje fibers (specialized cardiac muscle cells, see below) |
|
|
Term
| describe the characteristics of purkinje fibers |
|
Definition
much larger than ordinary cardiac muscle cells
have fewer myofibrils (thus stain lighter)
central nucleus (often binucleate) surrounded by a very prominent light area where glycogen accumulates |
|
|
Term
| what type of cells compose the conduction system of the heart? |
|
Definition
| highly specialized muscle cells called purkinje fibers |
|
|
Term
| an ischemic attack involving purkinje fibers can have what effect? |
|
Definition
| An ischemic attack involving areas where Purkinje fibers located can be fatal since damage to these fibers can result in the inability of the heart to contract rythmically and effectively |
|
|
Term
| describe the order of conduction in the heart |
|
Definition
| Impulses initiated at the sinoatrial node (pacemaker of the heart), travel to the atrioventricular node and then via the atrioventricular bundle (bundle of His) and its right and left bundle branches, to the apex of the heart |
|
|
Term
| the myocardium is homologous to which tunica? |
|
Definition
|
|
Term
| true or false: the myocardium is thicker in the ventricles than in the atria |
|
Definition
|
|
Term
|
Definition
Middle layer- homologous to tunica media
Thicker in the ventricles than in the atria.
In the ventricles, there is an inner circular layer and an outer spiral layer.
Cardiac muscle is anchored to the fibrous skeleton cardiac skeleton, a dense fibrous connective tissue layer.
heart muscle is postmitotic.
Ischemia due to coronary artery insufficiency can cause focal death of myocardial fibers.
Fibers are replaced by scar tissue |
|
|
Term
| the epicardium is homologous to which tunica layer? |
|
Definition
|
|
Term
| what type of epithelium is the outermost layer of the epicardium? |
|
Definition
|
|
Term
|
Definition
Outermost - homologous to the tunica adventitia.
Thick layer of loose connective tissue with variable amounts of adipose tissue.
Contains arteries, veins and nerves.
Outermost layer of the epicardium is a simple squamous epithelium.
This mesothelium is the visceral pericardium, a serous membrane that allows smooth movement of the heart within the pericardial sac. |
|
|
Term
| describe the tunica intima of large elastic arteries |
|
Definition
layer of endothelial cells resting on a thick subendothelium.
Connective tissue longitudinally oriented.
Internal elastic lamina not clearly defined because of other elastic laminae in media |
|
|
Term
| describe the tunica media of large elastic arteries |
|
Definition
concentrically arranged membranes of elastin (actually spiral).
Also contain smooth muscle.
Concentric, circularly arranged lamellae range from 40-70 layers thick.
Increase in number from infancy to adulthood.
Rebound of elastin in media helps maintain blood pressure during diastole (relaxation). |
|
|
Term
| describe the tunica adventitia in large elastic arteries |
|
Definition
relatively thin compared to the size of the vessel.
Contains vasa vasorum that extend into the media |
|
|
Term
| what is marfan's syndrome? |
|
Definition
Abnormal expression of the fibrillin gene.
Consequence is abnormal elastic tissue.
Cardiovascular abnormalities are life threatening.
Defect causes dissecting aneurysm of the aorta. |
|
|
Term
| what type of arteries are muscular arteries? (conducting or distributing) |
|
Definition
|
|
Term
| describe the tunica intima in muscular arteries |
|
Definition
layer of endothelial cells resting on subendothelial layer containing some smooth muscle.
Elements are longitudinally arranged.
Most prominent feature is the scalloped internal elastic lamina that separates the intima from the media.
The internal elastic lamina can frequently be seen, especially in larger muscular arteries, with a routine H&E stain |
|
|
Term
| what separates the tunica intima from the tunica media in muscular arteries? |
|
Definition
| the internal elastic lamina |
|
|
Term
| describe the tunica media in muscular arteries |
|
Definition
3 to 40 concentric layers of smooth muscle cells organized circularly.
various amounts of elastin membrane interspersed between smooth muscle layers, but unlike the internal elastic lamina, they are only seen when special stains are used. |
|
|
Term
| describe the tunica adventitia in muscular arteries |
|
Definition
External elastic lamina separates the media from the adventitia.
Contains longitudinally oriented fibroblasts, collagen fibers and elastic fibers.
Contains vasa vasorum and lymphatics. Vasa vasorum can extend into media. Lymphatics generally do not |
|
|
Term
| what separates the tunica adventitia from the tunica media in muscular arteries? |
|
Definition
|
|
Term
| what are some risk factors for atherosclerosis? |
|
Definition
age - atherosclerosis actually begins in childhood- in US, virtually everyone over 20 has some atherosclerotic changes in vessels
gender - males more prone than females, risk increases for women after menopause
genetics - family history
obesity
hypertension
smoking
Diabetes mellitus |
|
|
Term
| describe the sequence of events which occur during atherosclerosis |
|
Definition
Intimal thickening.
Proliferation of intimal smooth muscle cells and accumulation of lipid.
Lipid accumulates in macrophages and smooth muscle cells (foam cells).
Platelet-derived growth factor (PDGF) has been implicated in smooth muscle cell proliferation. Endothelium breaks down, platelets deposited, formation of plaque.
Plaque become vascularized by “vasa plaquorum”.
Expansion of lesion and fibrosis leads to vascular occlusion. |
|
|
Term
| what are some theories for the pathogenesis of atherosclerosis? |
|
Definition
number of theories:
Response-to-injury hypothesis.
This theory proposed the the initiating event in the formation of an atherosclerotic plaque was endothelial damage.
Some now believe that smooth muscle proliferation may be the initiating event since it has been found that smooth muscle cells in the lesion area are often from one or a few clones (“monoclonal hypothesis”). |
|
|
Term
| describe the tunica intima of arterioles |
|
Definition
layer of endothelial cells resting on a very thin subendothelium.
Internal elastic lamina not usually visible |
|
|
Term
| describe the tunica media of arterioles |
|
Definition
| 1 or 2 layers of concentrically arranged smooth muscle cells |
|
|
Term
| is the tunica adventitia of arterioles thick or thin? |
|
Definition
|
|
Term
| what are the 3 types of capillaries? |
|
Definition
| continuous, fenestrated, sinusoidal |
|
|
Term
| what is the function of capillaries? |
|
Definition
| exchange vessels, i.e. where exchange of nutrients, oxygen, carbon dioxide and metabolic waste products occurs |
|
|
Term
| describe continuous capillaries |
|
Definition
also called somatic capillaries
continuous endothelium joined by tight junctions (zonula occludens)
found in CNS, PNS, muscle, connective tissue and exocrine glands |
|
|
Term
| describe fenestrated capillaries |
|
Definition
Also known as visceral capillaries
characterized continuous endothelium interrupted by pores or fenestrae (windows).
In many organs, the pores have thin diaphragms over them.
In the renal glomeruli, the fenestrae have no diaphragms |
|
|
Term
| are macrophages associated with sinusoidal capillaries? |
|
Definition
|
|
Term
| what are sinusoidal capillaries? |
|
Definition
Also known as discontinuous capillaries.
Specialized capillaries with very large lumens relative to other capillaries.
Characterized by many open fenestrations and an absence of a continuous basal lamina.
Characterized by the presence of macrophages along their walls.
Found in the liver as well as in lymphoid and hematopoietic organs.
Big gaps in the walls |
|
|
Term
| what is the name for the macrophages which sit in the lumen near sinusoidal capillaries? |
|
Definition
|
|
Term
| what happens to the capillary basal laminae in an individual with diabetes mellitus and microvascular disease? |
|
Definition
| thickens abnormally; There is evidence of increase laminin and collagen type IV synthesis by endothelial cells |
|
|
Term
|
Definition
Small, postcapillary vessels.
Have very thin walls relative to the size of the lumen and relative to the arterioles with which they are paired.
Have functional characteristics of capillaries, i.e. they are exchange vessels |
|
|
Term
|
Definition
Small or medium sized veins have valves in their interiors.
Valves are formed by subendothelial connective tissue and as such have a covering of endothelium |
|
|
Term
| describe the tunica of veins |
|
Definition
| Thin intima, poorly developed media, very well developed adventitia |
|
|
Term
| describe the tunica of large veins |
|
Definition
Have thick intimas, relatively thin medias and prominent, well-developed adventitias.
The largest veins, such as the vena cava, have very prominent longitudinal bundles of smooth muscle in the adventitia |
|
|
Term
| how would one distinguish a large artery from a large vein? |
|
Definition
Large arteries have thick intimas, thick medias and very underdeveloped adventitias
Large veins have thick intimas, thin medias and very well developed adventitias frequently characterized by longitudinal bundles of smooth muscle |
|
|
Term
| how would one distinguish a muscular artery from a comparably-sized vein? |
|
Definition
Compare the size of the lumen to the thickness of the wall;
Muscular arteries appear very round in cross-section. The wall is very thick relative to diameter. Wall about 1/4 thickness of entire diameter. Muscular arteries have prominent internal elastic lamina, very well developed media. The adventitia is less well developed than the media and thinner.
Veins are seldom regularly shaped in cross section. The wall is thin relative to the vessel diameter. There is typically no prominent internal elastic lamina. Veins have thin media and thick adventitia |
|
|
Term
| describe lymphatic vessels |
|
Definition
Very thin-walled vessels
Lymphatic capillaries usually have larger, irregular lumens than vascular capillaries
Larger lymphatics very similar to veins but do not have well defined tunics.
Can have valves |
|
|
