Vessel Wall Anatomy
This deepest layer of a blood vessel wall consists of a continuous sheet of simple squamous epithelial cells joined by tight junctions to reduce friction against blood flow
What is the tunica intima (or tunica interna)?
these are the largest, most proximal arteries closest to the heart that contain elastic proteins and act as a pressure reservoir
What are elastic arteries?
Found in the skin, muscles, and brain, these are the least permeable and most common capillaries
What are continuous capillaries?
his short, low-pressure circulatory loop carries deoxygenated blood through its arteries away from the heart toward the lungs
What is pulmonary circulation?
This form of intrinsic control refers to the automatic, local adjustment of blood flow directly within blood vessels without relying on external nervous or endocrine signals
What is autoregulation
Composed of smooth muscle, this intermediate wall layer controls lumen diameter to regulate blood flow and blood pressure via vasoconstriction and vasodilation
What is the tunica media?
These intermediate arteries feature a thick tunica media to direct blood flow to specific organs
What are muscular arteries?
These capillaries feature plasma membrane pores to facilitate fluid and solute exchange in active absorption or filtration areas like the small intestine and kidneys
What are fenestrated capillaries?
The long, high-pressure loop that distributes oxygenated blood from the heart to all tissues in the body
What is systemic circulation?
In response to metabolic signals like low oxygen or elevated levels of carbon dioxide, ADP, and histamine, arterioles undergo this process to open pre-capillary sphincters and increase local tissue perfusion
What is vasodilation
Made mostly of collagen fibers, this superficial wall layer physically binds blood vessels to surrounding tissues and provides structural support
What is the tunica externa?
These thinnest, most distal arteries immediately precede capillary beds and regulate blood flow into true capillaries
What are arterioles?
Featuring large fenestrations, large intercellular clefts, and an incomplete basement membrane, these are the most permeable capillaries found in the liver, bone marrow, and spleen
What are sinusoid capillaries?
The three primary arterial branches of the celiac trunk that supply blood to the stomach, liver, and spleen
What are the gastric, hepatic, and splenic arteries?
This intrinsic control mechanism causes smooth muscle in the tunica media to contract when high blood pressure stretches the vessel wall, resulting in arteriolar vasoconstriction
What are myogenic controls
These blood vessels carry blood away from the heart, featuring thick walls, small lumens, high pressure, and no valves
What are arteries?
This arterial pressure is recorded during ventricular contraction and represents the highest point of arterial oscillation
What is systolic pressure?
These rings of smooth muscle located on arterioles open and close to regulate blood flow entering true capillaries
What are pre-capillary sphincters?
This vascular system routes nutrient- and toxin-rich venous blood from the GI tract through a second capillary bed in the liver before returning to systemic circulation
What is the hepatic portal system?
Across all capillary beds in the human body, this total volume of fluid is filtered out into the interstitial space each day
What is 20 liters
These vessels carry blood toward the heart under low pressure, featuring thin walls, large lumens, and internal valves to prevent backflow
What are veins?
These sensory receptors located in the carotid sinuses and aortic arch monitor changes in arterial blood pressure to initiate nervous system responses
Answer: What are baroreceptors?
This type of pressure pushes fluid out of capillaries into the interstitial space and is highest at the arteriolar end
What is hydrostatic pressure
The three major physical factors that assist low-pressure venous blood return back to the heart
What are the skeletal muscle pump, venous valves, and large-diameter lumens?
While 17 liters of fluid are reabsorbed into capillaries at their venous ends daily, this system picks up the remaining 3 liters of fluid along with leaked proteins to return them to circulation
What is the lymphatic system