Cardiovascular System Flashcards
What primordial layer does the cardiovascular system arise from?
- mesoderm > mesenchyme > angioblastic tissue > cardiovascular system
T/F: the cardiovascular system is the first functional system to develop in the embryo
- true, necessary for sufficient nutrients
How many heart chambers do fish have? amphibians? turtles? birds? mammals?
Describe embryonic development of the cardiovascular system
- cardiogenic field anterior and lateral to neural plate
- anteroposterior folding of the embryonic disk
- caudal fusion of endothelial cells into endocardial heart tubes
- endocardial heart tubes and venous system meet and fuse
- fusion of caudal portion of endocardial heart tubes, surrounded by myoblasts to form the myocardium
- creation of cardiac tube (bulbus cordis, ventricle, atrium)
- loop formation and partitioning of chambers
What kind of cells are in the cardiogenic field?
- endothelial cells only
What are the main parts of the embryonic heart?
- truncus arteriosus: divided into outflow trunks (aorta and pulmonary)
- atrium: will be divided into L and R atria
- bulbus cordis and ventricle: will be divided into L and R ventricle
Describe the development of internal heart structures
- primary atrial septum is forming, ostium primum between primary septum and endocardial cushion allows blood flow from R to L atrium.
- primary atrial septum grows and fuses with the endocardial cushion, closing ostium primum. ostium secundum opens in the primary septum. ventricular septum is growing
- secondary atrial septum grows to the right of the septum primum, forming the foramen ovale. blood still flows from R to L atrium, but secondary septum acts as a valve to prevent backflow. ventricular septum is now complete
- embryo is born, first birth causes pressure drop in heart which causes septum primum to be pushed against the septum secundum resulting in the functional closure of the foramen ovale (morphological closure happens later when fuses: fossa ovalis)
When the heart is developing its internal structures, it is also twisting. Why? If it doesn’t what is the result?
- the truncus arteriosus is divided into an ascending aorta and pulmonary trunk by a spiral aortic pulmonary septum, which ensures that blood flows from R ventricle to pulmonary trunk, and L ventricle to ascending aorta
- if this doesn’t occur: straight septum aka TRANSPOSITION OF THE GREAT VESSELS…. which is not compatible with life
What are three unique features of fetal circulation that must close soon after birth?
- ductus arteriosus
- umbilical arteries
- foramen ovale
What are the functions of the cardiovascular system?
- maintenance of adequate blood flow (cardiac output)
- delivery of O2, nutrients, hormones, electrolytes, and water to peripheral tissues
- removal of O2 and other metabolic waste products
- maintenance of thermoreguation
- maintenance of glomerular filtration rate and urine output
What is the path of circulation?
- artery > arterioles > metarteriole > capillaries
> venule > vein
What are features of the heart?
- first organ to form in embryo
- 3 tunics
- endocardium (includes valves)
- myocardium (heart muscle)
- epicardium (visceral pericardium)
Label the arrows
What are some features of endocardium?
- forms inner lining and valves
- equivalent to tunica intima in BV
- endothelial cells on innermost surface
- direct contact w/ blood
- important in hemostasis
- 3 layers
Describe the 3 layers of endocardium
- endothelium
- basal lamina
- sub-endothelial connective tissue
What is this structure?
- valve cusp
What is shown here? What are some features?
- myocardium
- involuntary
- cross-striated
- central single nucleus
- intercalated discs (w/ gap junctions and anchoring junctions)
- lipofuscin
- sarcoplasmic reticulum
- many mitochondria (up to 20% cell volume, requires lots of O2, low generation capacity)
What are purkinje cells?
- modified cardiomyocytes that function in conduction
- located in endocardium
What are some features of the epicardium?
- outer surface of heart (visceral pericardium)
- surface is covered by mesothelium (simple squamous epithelium), a thin layer of dense CT, and a variably thick layer adipose tissue with blood vessels
- contiguous with the endocardium at the level of the endocardial cushion
- mesothelium cell layer lines opposing parietal surface of the pericardial sac, secreting small amounts of serous fluid that lubricates movement of the epicardium
What is this structure?
- elastic artery
What is this structure?
- muscular artery
What is this structure?
- elastic artery
What are some features of arterioles?
- 1-3 layers of SM cells
- greatest effect on blood pressure
- nuclei bulge into lumen
- round appearance of vessel
-no internal elastic membrane in the smallest arterioles with only one SM cell - metarteriole is a terminal vessel, as pre-capillary sphincters that can regulate flow to capillary bed
What are the three kinds of capillaries?
What is this? What are some features?
- continuous capillary
- nucleus of endothelial cell
- pinocytotic vesicles
- tight junctions
- basement lamina/membrane
What is this an example of?
- fenestrated capillaries
- the Renal corpuscle (glomerulus) is a tightly coiled network of fenestrated capillaries and is responsible for filtration of plasma
What is this? What are some features?
- discontinued capillaries (sinusoids)
- lumen is enlarged and irregular
- lining endothelium is discontinued and fenestrated
- basal lamina may be absent
What are some features of pericytes (Roujet cells)
- mesenchymal-like cells that wrap around the endothelium of capillaries and venules
- communicate with endothelial cells physical contact and paracrine signaling
- help maintain homeostatic and hemostatic functions in the brain and sustain the blood-brain barrier
- proliferate after injury
- stem cell source
- important in angiogenesis (new vessel formation)
What are some features of podocytes?
- lining the bowman’s capsules (nephrons)
- help prevent proteins and other large molecules from being filtered
- foot processes extend and wrap around the capillaries of the glomerulus to form filtration slits
- the pedicels increase the area of cells enabling efficient ultrafiltration
What are some features of venules?
- “postcapillary venules”
- “leaky” vessels
- no smooth muscle
- leukocyte diapedesis possible
What is pictured? What are some features?
- vein
What are some differences of veins compared to arteries?
- large, wide lumen, thin walls in comparison to similarly sized arteries
- valves present
- thin tunica media
- tunica adventitia is thickest layer
- large veins may have vasa vasorum
- may be collapsed in histological sections
What is this? What are some features?
- lymphatic vessel
- very thin wall (smooth muscle)
- very low pressure
- may contain valves
- no RBC in lymph, so appears clear
- complementary to the cardiovascular system
- freely anastomose with each other
- lined by endothelial cells
- adventitia binds lymph vessels to surrounding tissue
