Nerves, Vessels and Lymphatics Flashcards
Describe blood vessels
Are a closed system of endothelium tubes. Their function is the return deoxygenated blood to the heart and distribute oxygenated blood to capillary beds
What are the three layers of blood vessels and what are they made of?
Blood vessels have 3 layers and they are called tunicas;
tunica intima:
Endothelium
tunica medica:
Elastic tissue/ smooth muscle
tunica adventitia/ externa:
Connective tissue
What layers do capillaries have?
Tunica intima (endothelium)
What is the cycle of blood?
Elastic artery, muscular artery, small muscular arteries, arterioles, capillary, venues, small veins, medium veins, large veins, heart.
Describe elastic arteries
Largest artery, receives blood from the heart at high pressure
The tunica media (elastic tissue, smooth muscle) is thick to maintain blood pressure during ventricular diastole.
Describe muscular arteries
Radial, femoral artery. The tunica media consists of 6 layers of smooth muscle
Describe the arterioles
Regulate blood flow through capillary bed
Regulates systemic blood pressure
Its tunica media only has 1 or 2 layers of smooth muscle.
Describe the capillaries
Exchange vessels, lined by endothelial cells + basal lamina
Describe pericytes
Located in capillaries,
Undifferentiated calls (form new cells)
Resemble modified smooth muscle cells
Contractile cells
Describe veins
Returns deoxygenated blood to the heart
In veins, tunica adventitia is the thickest
Function is aided by smooth muscle of tunica media, valves and contraction of surrounding skeletal muscle
Few smooth muscle cells in tunica media
Describe large muscular veins
longitudinal smooth muscles in adventitia causes pumping of blood to oppose action of gravity
Low blood pressure.
What are some differences between arteries and veins?
In arteries, the tunica media is the thickest. While in veins the tunica adventitia is the thickest.
Veins have thinner walls than arteries
Arteries are more rounded while veins are more irregular
blood cells are more likely to be found in veins than arteries.
What do neurovascular bundles include?
Artery, veins, lymphatics, nerves, venule, arteriole
What are lymphatic vessels?
Lymphatic vessels are blind ending lymphatic capillaries which receive extracellular fluid which becomes lymph.
They have very thin walls which collapse and make it hard for H&E staining.
What is the structure of lymphatic vessels?
Extremely thin walls Leaky - allows ECF to become lymph No basement membrane of pericytes Lumen is opened by elastic microfibrils Lymphatics vessels have valves
Describe lymph nodes
Lymph nodes are encapsulated lymphoid organs
they ‘sample’ the lymph and are usually found in the axilla (armpit), groin and mensenteries
Are found along the pathway of lymphatic vessels.
What are the surface features of lymph nodes?
Dense irregular CT, multiple afferent lymphatic vessels, Projections of capsule into parenchyme = trabeculae
Lymph nodes are drained by efferent vessels at the hilum. The hilum is where blood vessels enter and leave lymph node
Describe the parenchyma (including the structure)
Macrophages line sinuses and they phagocytose antigens. Follicles in cortex contain B cells and produce antibodies. The paracortex also contains T cells
It has three components
Superficial cortex
(densely packed lymphocytes, nodules present)
Paracortex (deep cortex)
Medulla
