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Questions and Answers
Which artery originates from the aortic arch and supplies the arm?
Which artery originates from the aortic arch and supplies the arm?
What is the function of the Internal Carotid artery?
What is the function of the Internal Carotid artery?
Which vein is associated with deep veins of the upper limb?
Which vein is associated with deep veins of the upper limb?
Which vein drains blood from the brain?
Which vein drains blood from the brain?
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Which superficial vein connects to the femoral vein?
Which superficial vein connects to the femoral vein?
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What are the two systems that comprise the circulatory system?
What are the two systems that comprise the circulatory system?
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What is the primary function of plasma in the blood?
What is the primary function of plasma in the blood?
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Which component of blood is primarily responsible for the transportation of oxygen?
Which component of blood is primarily responsible for the transportation of oxygen?
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What are the main types of leukocytes in the blood?
What are the main types of leukocytes in the blood?
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What is the primary function of arteries?
What is the primary function of arteries?
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What is the role of hemoglobin in red blood cells?
What is the role of hemoglobin in red blood cells?
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How does blood circulation support thermoregulation?
How does blood circulation support thermoregulation?
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Which layer of a blood vessel is primarily responsible for vasoconstriction and vasodilation?
Which layer of a blood vessel is primarily responsible for vasoconstriction and vasodilation?
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What characteristic differentiates veins from arteries?
What characteristic differentiates veins from arteries?
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Which statement correctly differentiates between the cardiovascular and lymphatic systems?
Which statement correctly differentiates between the cardiovascular and lymphatic systems?
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What is the smallest type of blood vessel that facilitates exchange of gases and nutrients?
What is the smallest type of blood vessel that facilitates exchange of gases and nutrients?
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Which of the following correctly describes erythrocytes?
Which of the following correctly describes erythrocytes?
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Which statement about venules is true?
Which statement about venules is true?
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Which statement accurately describes an open circuit in the body?
Which statement accurately describes an open circuit in the body?
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What is the primary function of the pulmonary circuit?
What is the primary function of the pulmonary circuit?
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Which statement best describes the systematic circulation?
Which statement best describes the systematic circulation?
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What is the primary role of the hepatic portal system?
What is the primary role of the hepatic portal system?
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Which of the following arteries is the largest in the human body?
Which of the following arteries is the largest in the human body?
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How does arterial circulation differ from venous circulation?
How does arterial circulation differ from venous circulation?
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Which feature is characteristic of systemic veins?
Which feature is characteristic of systemic veins?
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What describes the relationship between the aorta and vena cavas?
What describes the relationship between the aorta and vena cavas?
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Which type of capillary is most permeable and has wide, leaky openings?
Which type of capillary is most permeable and has wide, leaky openings?
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What is the primary function of capillaries in the lungs?
What is the primary function of capillaries in the lungs?
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Which feature distinguishes continuous capillaries from fenestrated capillaries?
Which feature distinguishes continuous capillaries from fenestrated capillaries?
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Where are fenestrated capillaries primarily found?
Where are fenestrated capillaries primarily found?
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Which type of artery is characterized by a thick tunica media and is responsible for distributing blood?
Which type of artery is characterized by a thick tunica media and is responsible for distributing blood?
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What regulates blood flow to capillary beds?
What regulates blood flow to capillary beds?
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In which organ would you predominantly find sinusoid capillaries?
In which organ would you predominantly find sinusoid capillaries?
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Which of the following statements about capillary permeability is correct?
Which of the following statements about capillary permeability is correct?
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Study Notes
Circulatory System Overview
- The circulatory system is composed of the cardiovascular and lymphatic systems.
- Blood is a specialized connective tissue that serves as a transport medium for nutrients, signaling molecules, respiratory gases, and waste products.
- Blood also stabilizes pH and electrolytes, prevents fluid loss through clotting, and provides defense against pathogens
- Blood is comprised of formed elements (blood cells) and plasma (liquid portion).
Blood Components
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Plasma: The straw-colored, sticky fluid portion of blood, containing over 100 types of molecules. It is primarily water (90%), and contains:
- Ions: Sodium (Na+) and Chloride (Cl-)
- Nutrients: Sugars, amino acids, and lipids.
- Wastes: Carbon dioxide, urea, and ammonia.
- Proteins: Fibrinogen, albumin, and globulins.
- Fibrinogen: Involved in blood clotting
- Albumin: Prevents water from diffusing out of blood vessels.
- Globulins: Antibodies and blood proteins that transport lipids, iron, and copper.
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Buffy Coat: The thin, whitish layer between plasma and erythrocytes, containing leukocytes (white blood cells) and platelets.
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Erythrocytes (Red Blood Cells): Oxygen-transporting cells lacking organelles and nuclei. They are packed with hemoglobin, a protein containing four chains of amino acids, each bound to an iron atom and a heme molecule that binds with oxygen.
Blood Circulation
- The heart's pumping action powers blood circulation.
- Oxygen and nutrients diffuse across capillary walls to tissues.
- Circulation also transports hormones from endocrine glands and immune system cells.
- Thermoregulation (blood temperature regulation) is a function of blood circulation.
Open and Closed Circuits
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Open Circuit: A system exposed to the external environment, like the respiratory and digestive systems, which take in air and food from the outside.
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Closed Circuit: A system not normally exposed to the external environment, like the circulatory system. The vessels and blood do not come in contact with anything external.
Arterial and Venous Circulation
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Arterial Circulation: Carries oxygen-rich blood away from the heart; high pressure.
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Venous Circulation: Carries oxygen-poor blood back to the heart; low pressure.
Circulatory System Divisions
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Pulmonary Circuit: The right side of the heart receives oxygen-poor blood from the body and pumps it to the lungs for oxygenation.
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Systemic Circuit: The left side of the heart receives oxygenated blood from the lungs and pumps it throughout the body to deliver oxygen.
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Hepatic Portal System: A venous system that drains the intestines, where digested nutrients are absorbed, into the liver. The liver processes these nutrients before they enter systemic circulation.
Major Blood Vessels
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Aorta: The largest artery, branching into:
- Ascending Aorta: Arises from the left ventricle; supplies the heart with blood.
- Aortic Arch: Lies posterior to the manubrium; branches into the brachiocephalic trunk, left common carotid, and left subclavian arteries.
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Descending Aorta: Continues from the aortic arch, branching into:
- Thoracic Aorta: Extends from T5 to T12; supplies the chest and back.
- Abdominal Aorta: Extends from T12 to L4; supplies the abdomen and pelvis.
- Divides into the left and right common iliac arteries.
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Vena Cava: The largest vein, carrying deoxygenated blood.
- Superior Vena Cava: Drains the head, upper limbs, and thorax; empties into the right atrium.
- Inferior Vena Cava: Drains the abdomen, pelvis, and lower limbs; empties into the right atrium.
Regional Blood Vessels
Upper Limb Arteries
- Originate from the aortic arch (brachiocephalic trunk):
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Subclavian (neck)
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Axillary (armpit)
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Brachial (arm)
- Radial artery and Ulnar artery (forearm)
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Brachial (arm)
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Axillary (armpit)
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Subclavian (neck)
Major Arteries of the Head
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Common Carotid artery
- External carotid artery: Supplies face and scalp.
- Internal carotid artery: Supplies brain.
Major Arteries of the Lower Limb
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Common Iliac artery
- Internal Iliac artery: Supplies pelvis.
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External Iliac artery: Supplies the thigh
- ** Femoral artery**
- **Popliteal artery **
- Anterior and Posterior Tibial artery (leg)
Veins of the Head
- Internal Jugular: Drains the brain.
- External Jugular: Drains the face and scalp.
Veins of the Upper Limb
- Deep Veins: Follow the paths of companion arteries; share the same names.
- Superficial Veins: Visible beneath the skin: - Cephalic Vein - Basilic Vein - Median Cubital Vein - Median Vein of the Forearm
Veins of the Abdomen
- Tributaries of the Inferior Vena Cava: - Lumbar Veins - Gonadal Veins - Renal (kidney) Veins - Suprarenal Veins - Hepatic (liver) Veins
Veins of the Pelvis and Lower Limb
- Deep Veins: Share the name of the accompanying artery.
- Superficial Veins: - Great saphenous vein empties into the femoral vein. - Small saphenous vein empties into the popliteal vein.
Blood Vessel Structures
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Types
- Arteries: Carry blood away from the heart.
- Arterioles: The smallest arteries, with diameter controlled by local tissues or the sympathetic nervous system.
- Capillaries: The smallest blood vessels, where exchange of nutrients, gases, and waste occurs.
- Veins: Carry blood towards the heart; have thinner walls and larger lumens than arteries.
- Venules: The smallest veins, receiving blood from capillaries.
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Structure
- Lumen: The central blood-filled space of the vessel.
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Tunics: Three layers comprising the blood vessel walls:
- Tunica Intima: The innermost layer, containing endothelium (simple squamous epithelium) and a subendothelial layer in larger vessels.
- Tunica Media: The middle layer, composed of smooth muscle; responsible for vasoconstriction (contraction) and vasodilation (relaxation).
- Tunica Externa: The outermost layer, composed of connective tissue.
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Differences between Arteries and Veins
- Veins have larger lumens to accommodate a larger volume of blood (65% of the body's blood is in veins).
- Veins have thicker tunica externa.
- Veins have less elastin in their walls.
- Veins have thinner walls than arteries of comparable size.
Capillaries
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The smallest blood vessels, allowing red blood cells to pass through single file.
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Their function is site-specific:
- Lungs: Oxygen enters the blood, carbon dioxide leaves.
- Small Intestines: Receive digested nutrients.
- Endocrine Glands: Pick up hormones.
- Kidneys: Remove nitrogenous wastes.
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Types of Capillaries:
- Continuous Capillaries: Most common type, found in most organs. The epithelial cells are joined by tight junctions and desmosomes, with small gaps called intercellular clefts that allow the passage of small molecules.
- Fenestrated Capillaries: Similar to continuous capillaries but with pores in the endothelium, allowing greater exchange, found in the small intestine, glomeruli of the kidneys, and endocrine glands.
- Sinusoid Capillaries: The most permeable, with large, leaky capillaries and wide intercellular clefts. They occur in the liver, bone marrow, and spleen.
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Capillary Permeability:
- Direct Diffusion: Substances pass directly through the endothelial cell membrane.
- Intercellular Clefts: Spaces between endothelial cells allow small molecules to pass through.
- Fenestrations: Pores allow even larger molecules to pass.
- Pinocytotic Vesicles: Endothelial cells form vesicles that engulf substances and transport them across the capillary wall.
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Capillary Beds: Networks of capillaries running through tissues.
- Precapillary Sphincter: Smooth muscle rings that control blood flow to capillaries.
- Tissues: Tendon and ligaments are poorly vascularized; epithelia and cartilage are avascular and receive nutrients from nearby connective tissue.
Types of Arteries
- Elastic Arteries: The largest, also called "conducting arteries" (e.g., aorta and its major branches). They have a high elastin content, which helps dampen the surge of blood pressure.
- Muscular Arteries: Also called "distributing arteries" (e.g., most arteries). They have a thick tunica media and contain internal and external elastic membranes.
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Description
Explore the fundamentals of the circulatory system, including the cardiovascular and lymphatic systems. Understand the structure and function of blood, its components, and the roles of plasma, cells, and proteins. This quiz covers essential concepts that are crucial for comprehending human physiology.
