Cardiovascular System: Vessels & Circulation

Flashcards for Cardiovascular System: Vessels & Circulation

Three Tunics of Vessels

The three tunics common to most vessels are the tunica intima, tunica media, and tunica externa.

Distinguishing Features: Arteries, Capillaries, and Veins

Arteries have thicker walls and a narrower lumen than veins; capillaries are thin-walled for exchange.

Types of Arteries

Elastic arteries are the largest, muscular arteries have a thick tunica media, and arterioles regulate blood flow into capillaries.

Capillary Structure and Function

Capillaries are small vessels that connect arterioles and venules to facilitate the exchange of substances between blood and tissues.

Types of Capillaries

Continuous capillaries have tight junctions, fenestrated capillaries have pores, and sinusoids are leaky with large gaps.

Blood Flow in Capillary Bed

Blood moves from arterioles to capillaries to venules within a capillary bed.

Vein Structure and Function

Veins have thinner walls, wider lumens, and valves to prevent backflow.

Veins as Blood Reservoir

Veins act as a blood reservoir due to their ability to expand and hold a large volume of blood.

Simple vs. Alternative Pathways

Simple pathways involve one artery, one capillary bed, and one vein, while alternative pathways involve more complex routes.

Tunica Media Tissue

Smooth muscle makes up most of the tunica media.

Largest Type of Artery

Elastic artery

Portal System

A portal system is a system of vessels where blood passes through two capillary beds in series, such as the hepatic portal system.

Leakiest Type of Capillary

Sinusoid

Fenestration & Sinusoid

A fenestration is a small pore in a capillary wall; a sinusoid is a dilated, irregular blood-filled space.

Capillary Bed Structures

Capillary beds consist of arterioles, capillaries, and venules, with precapillary sphincters controlling blood flow.

Control of Capillary Blood Flow

Precapillary sphincters control blood flow into a capillary bed based on local tissue needs.

Cross-Sectional Area & Blood Flow Velocity

The total cross-sectional area is inversely related to the velocity of blood flow.

Capillaries: Smallest Vessels, Largest Area

Capillaries are numerous, thus their total cross-sectional area is the largest.

Significance of Slow Capillary Blood Flow

Slow blood flow in capillaries allows for efficient exchange of gases, nutrients, and wastes.

Vein Blood Flow Velocity

Blood flow velocity in veins is faster than in capillaries but slower than in arteries.

Capillary Exchange Mechanisms

Diffusion involves movement down concentration gradients; vesicular transport moves larger molecules across capillary walls.

Vasomotion

Vasomotion refers to the intermittent contraction and relaxation of precapillary sphincters.

Vessel Valve

A vessel valve is a flap of tissue in veins that prevents backflow; found mostly in limb veins.

Blood Reservoir Vessel

Veins

Types of Vessel Pathways

Vessel pathaways include simple and alternate pathways, such as portal systems and anastomoses.

Anastomosis

An anastomosis is a connection between blood vessels providing alternate routes for blood flow.

Bulk Flow, Filtration, Reabsorption

Bulk flow involves the movement of fluid and solutes; filtration is fluid movement out of blood; reabsorption is fluid movement into blood.

Hydrostatic vs. Colloid Osmotic Pressure

Hydrostatic pressure pushes fluid out of capillaries; colloid osmotic pressure draws fluid into capillaries.

Net Filtration Pressure (NFP)

Net filtration pressure (NFP) is the net pressure driving fluid movement across the capillary wall.

Lymphatic System at Capillary Bed

The lymphatic system collects excess fluid from the capillary bed and returns it to the bloodstream.

Oxygen Movement Mechanism

Diffusion

Filtration

The movement of fluid out of the blood.

Higher Colloid Osmotic Pressure at most Body Capillaries

COPif

Dominant Process at Arterial End of Capillary

Filtration

Degree of Vascularization

Degree of vascularization refers to the extent of blood vessel distribution in a tissue.

Angiogenesis & Perfusion

Angiogenesis is the formation of new blood vessels, aiding perfusion by increasing blood supply.

Myogenic Response

The myogenic response maintains blood flow by altering vessel diameter in response to changes in blood pressure.

Vasodilator vs. Vasoconstrictor

A vasodilator widens blood vessels, while a vasoconstrictor narrows them.

Tissue Autoregulation

Tissues autoregulate by adjusting blood flow based on metabolic needs, using local factors like oxygen and pH.

Total vs. Local Blood Flow

Total blood flow remains constant, while local blood flow varies based on tissue needs.

CO2 & Lactic Acid Effect

High levels of carbon dioxide and lactic acid stimulate vasodilation.

Histamine Effect

Histamine triggers vasodilation.

Myogenic Response to High BP

The myogenic response to a rise in systemic blood pressure is vasoconstriction.

Angiogenesis

The formation of new blood vessels.

Blood Pressure & Gradient

Blood pressure is the force exerted by blood on vessel walls; a blood pressure gradient is the pressure difference between two points.

BP & Gradients in Vessels

Arteries have high pressure and steep gradients, capillaries have decreasing pressure, and veins have low pressure and small gradients.

Pulse Pressure & MAP

Pulse pressure is the difference between systolic and diastolic pressure; MAP is diastolic pressure plus one-third of pulse pressure.

Overcoming Venous Pressure Gradient

Mechanisms include valves, skeletal muscle pump, and respiratory pump.

Resistance

Resistance is opposition to flow influenced by viscosity, vessel length, and vessel radius.

BP Gradient, Resistance & Flow

Blood flow is directly proportional to the blood pressure gradient and inversely proportional to resistance.

Resistance & Blood Pressure

Increased resistance increases blood pressure because the heart must work harder to maintain flow.

Blood Pressure in Vessels

Arteries have highest pressure, capillaries intermediate, and veins lowest.

Pulse Pressure & MAP Calculation

PP = 30 mm Hg, MAP = 100 mm Hg

Mechanisms Pumping Blood Through Veins

Valves, skeletal muscle pump, and respiratory pump.

Vasoconstriction Effect on Resistance & Flow

Vasoconstriction increases resistance, decreasing blood flow.

Short-Term BP Regulation

Short-term mechanisms involve baroreceptors, chemoreceptors, and autonomic reflexes.

Baroreceptor Reflex

The baroreceptor reflex involves receptors detecting pressure changes and signaling the brain to adjust heart rate and vessel diameter.

Chemoreceptor Effects on BP

Chemoreceptors detect changes in blood gases and pH, influencing respiration and vasoconstriction.

Autonomic Reflexes & BP

Autonomic reflexes adjust heart rate, contractility, and vessel diameter to maintain blood pressure.

Hormones Regulating BP

Hormones like epinephrine, norepinephrine, ADH, and angiotensin II regulate blood pressure.

Renin-Angiotensin System

The renin-angiotensin system increases BP by stimulating vasoconstriction and aldosterone release.

Hormonal BP Effects

Aldosterone, ADH, and angiotensin II increase BP, while ANP decreases it.

Carotid Artery Pressure Fall

Rapid standing causes a fall in carotid artery pressure, triggering vasoconstriction and increased heart rate.

How Aldosterone Prevents BP fall

increasing sodium and water reabsorption in the kidneys.

ANP effect on Blood Pressure

Atrial natriuretic peptide (ANP) lowers blood pressure by promoting vasodilation and sodium excretion.

Vasomotor Center

The vasomotor center in the brainstem controls blood vessel diameter.

Blood Flow During Exercise

During exercise, total blood flow increases, and distribution shifts to skeletal muscles.

Tissues with increased blood flow during exercise

Skeletal muscle, heart, and skin

Pulmonary Circuit Pathway

Right ventricle, pulmonary trunk, pulmonary arteries, lungs, pulmonary veins, left atrium.

Pulmonary vs Systemic Circulation

Pulmonary circulation has lower pressure and resistance compared to systemic circulation.

Pulmonary veins to Heart Chamber

Left atrium

Number of Pulmonary Veins attaching to Heart

Four

Pressure Comparison: Pulmonary Trunk & Aorta

The pressure in the pulmonary trunk is lower than the pressure in the aorta.

Arteries from Left Ventricle

Aorta, brachiocephalic trunk, left common carotid artery, left subclavian artery

Veins returning blood from Systemic Circulation

Superior vena cava, inferior vena cava, coronary sinus

Vessels of Aortic Arch

Brachiocephalic trunk, left common carotid artery, left subclavian artery

Two Vessels froming the superior Vena Cava

Brachiocephalic veins

Arteries/Veins of Head & Neck

Arteries: common carotid, vertebral; Veins: internal jugular, external jugular

Cerebral Arterial Circle

Also known as the Circle of Willis, provides alternate routes for blood flow in the brain.

Dural Venous Sinuses

Dural venous sinuses are venous channels located between the dura mater that drain blood from the brain.

Arteries/Veins of Thoracic Wall

Arteries: internal thoracic, posterior intercostal; Veins: azygos, hemiazygos

Arteries/Veins of Abdominal Wall

Arteries: superior and inferior epigastric arteries; Veins: epigastric veins

Veins draining thoracic and abdominal walls and delineating thier pathways

Azygos, hemiazygos, lumbar veins draining abdominal wall

Vessels of Lungs, Esophagus, Diaphragm

Bronchial arteries/veins (lungs), esophageal arteries/veins (esophagus), phrenic arteries/veins (diaphragm).

Major Arteries of the GI Tract

Celiac trunk, superior mesenteric artery, inferior mesenteric artery

Hepatic Portal System

The hepatic portal system delivers blood from the GI tract to the liver for processing.

GI Tract to Inferior Vena Cava Blood Route

Gastrointestinal tract, hepatic portal vein, liver, hepatic veins, inferior vena cava.

Arteries/Veins of Adrenal glands, Kidneys, Gonads

Arteries: suprarenal, renal, gonadal arteries; Veins: suprarenal, renal, gonadal veins

Main Vessels of Pelvis & Perineum

Internal iliac artery/vein…

Left Ventricle to Right Internal Carotid Artery

Left ventricle, aorta, brachiocephalic trunk, right common carotid artery, right internal carotid artery.

Side of Body with Azygos Vein

Right

Definition: Hepatic Portal System

A system of vessels carrying blood from the GI tract to the liver.

Gastroduodenal Origin

Celiac Trunk

Arteries of Upper Limb

Subclavian artery, axillary artery, brachial artery, radial/ulnar arteries, palmar arches, digital arteries.

Upper Limb Veins

Superficial: cephalic, basilic; Deep: radial, ulnar

Arteries of Lower Limb

External iliac artery, femoral artery, popliteal artery, anterior/posterior tibial arteries, dorsalis pedis artery, plantar arteries, digital arteries.

Lower Limb Veins

Superficial: great saphenous, small saphenous; Deep: anterior/posterior tibial, fibular

Popliteal vein, femoral vein, external iliac vein, common iliac vein, inferior vena cava, right atrium.

Back of Knee to Right Atrium Blood Route

Elbow Vein for Blood Draw

Median cubital vein

Subclavian Artery After First Rib

Axillary Artery