Histology - Vasculature Flashcards
Medium size, continuous basal lamina, have small openings through plasma membrane that may or may not be closed by a diaphragm. Found in endocrine organs, GI tract, and kidney.
Fenestrated (type II) Capillaries
Most external layer composed of fibroelastic connective tissue that is continuous with and blends into CT. Contains ANS postganglionic nerve fibers that innervate the smooth muscle cells in the TM and vasa vasorum for nutrients.
tunica adventitia (TA)
Initially left and right associated with arch 6, but when arch 6 is lost from the right side, it ‘slides’ up to arch 4, while arch 6 remains in place (ductus arterosus).
Recurrent laryngeal nerve fetal development
Secreted by endoderm & visceral mesoderm, upregulates expression of FGF8 gene
BMP 2, 4
Directly controls amount of blood flow through capillary beds
Precapillary sphincter
a small ligament attached to the superior surface of the left pulmonary artery and the proximal descending aorta. a nonfunctional vestige of the ductus arteriosus, and is formed within three weeks of birth.
ligamentum arteriosum
L ventricle to left atrium -> foramen ovale to right atrium -> to right ventricle to pulmonary trunk -> DUCTUS ARTERIOSUS
Compensatory blood flow (prenatal) in preductal constriction of the aorta
right sinus horn
upper part of the IVC fetal derivative
6-8 microns in diameter (smallest), found in tightest tight junctions, prominent pinocytotic vesicles. Continuous and complete basal lamina, found everywhere.
Continuous (type I) capillary
Tunica media: 5-40 layers smooth muscle arranged in a spiral fashion. Prominent IEL & EEL.
Muscular (distributing) arteries
(1) SVC (2) upper part of the IVC (3) incorporated into the right atrium (smooth part)
Right sinus horn becomes
Subclavian aa -> Internal thoracic arteries -> Anterior intercostal -> arteries -> Posterior intercostal arteries -> Thoracic aorta (to lower body & Les)
Postductal coarctation of the Aorta collateral circulation
Partitioning of the heart into 4 chambers begins.
Week 5 Heart Development
a collection of veins joined together to form a large vessel that collects blood from the heart muscle
coronary sinus
- Enlargement of collateral arteries. 2. X-ray: Notching of ribs (on posterior 1/3). 3. Despite compensation, blood pressure in UEs much higher than in LEs
Postductal coarctation of the Aorta presentation
Thin tunica intima & adventita. Tunica media made of 1-4 layers smooth muscle. May have IEL but no EEL. They control blood flow into capillary beds by increasing or decreasing lumen diameter (thereby or vascular resistance to blood flow). They are the principal control of systemic blood pressure
Arterioles
Aortic arches undergo primary changes to adult form.
Week 6 Heart Development
common cardinal vein, Umbilical vein, Vitelline vein
intial sinus horn inflow
Endothelium: Weibel-Palade bodies, Subendothelial connective tissue (CT) layer, Internal elastic lamina (IEL, where applicable)
Tunica intima
Wedge-shaped portion of aortic arch, Ductus arteriosus (ligamentum arteriosum)
Aortic arches become…
Each arch develops its own artery, nerve that controls a distinct muscle group, and skeletal tissue. The arches are numbed from 1 to 6, with 1 being the closest to the head of the embryo, and 5 existing only transiently. They develop during the fourth week crainal to caudal on both sides of the developing pharynx.
Aortic and associated pharyngeal arches
- Endothelial cell regrowth (from uninjured areas) 2. Smooth muscle cell migration into the tunica intima. 3. Smooth muscle cell proliferation. 4. Smooth muscle cell secretion of ECM.
Vascular injury associated with endothelial cells loss or dysfunction results in…
a depression in the right atrium of the heart, the remnant of a thin fibrous sheet that covered the foramen ovale during fetal development.
fossa ovalis
Smooth muscle layers: Fenestrated elastic sheets/laminae (elastic arteries), External elastic lamina (EEL, where applicable)
Tunica media
contractile cell located within endothelial basal lamina that communicate with endothelial cell via gap junctions that are ctivated with injury & during wound healing. They are mesenchymal –type cells tha can act as stem cell and give rise to: endothelial cells & smooth muscle cells during angiogenesis.
Pericytes (Rouget cells)
Relatively wide, irregular lumen, thinner walls, valves and no internal elastic lamina.
Medium vein (MV)
Arranged in networks. Consist of endothelial cells, basal lamina, and pericytes.
Capillaries
Blood flow into the right atrium from the IVC to the left atrium, bypassing pulmonary circulation.
Foramen ovale