Circulatory System Overview

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Questions and Answers

What is the primary shape of red blood cells?

  • Flat discs
  • Biconcave disks (correct)
  • Spherical
  • Cylindrical

What is the key function of hemoglobin in red blood cells?

  • To bind and transport oxygen (correct)
  • To fight infections
  • To transport nutrients
  • To produce ATP

What color does oxyhemoglobin appear when bound to oxygen?

  • Deep blue
  • Bright red (correct)
  • Pale yellow
  • Dark brown

How is ATP generated in red blood cells?

<p>Anaerobically without oxygen (B)</p> Signup and view all the answers

What physiological condition is indicated by a high total white blood cell count?

<p>Leukocytosis (A)</p> Signup and view all the answers

Why is the flexible plasma membrane of red blood cells important?

<p>To enable movement through capillaries (C)</p> Signup and view all the answers

What percentage is considered a normal total white blood cell count?

<p>4500 - 11000 cells per microliter (A)</p> Signup and view all the answers

What occurs to hemoglobin when oxygen diffuses into body tissues?

<p>It becomes deoxyhemoglobin (C)</p> Signup and view all the answers

What is the primary role of neutrophils in the immune system?

<p>To phagocytize infectious pathogens and bacteria (C)</p> Signup and view all the answers

What distinguishes eosinophils from other white blood cells?

<p>Their bi-lobed nucleus and reddish-pink staining granules (D)</p> Signup and view all the answers

Which type of white blood cell orchestrates the immune response against viral infections?

<p>T-lymphocytes (D)</p> Signup and view all the answers

What is the function of basophils during inflammatory reactions?

<p>To release histamine and heparin (B)</p> Signup and view all the answers

Which of the following white blood cells is typically the most abundant in a healthy individual?

<p>Neutrophils (D)</p> Signup and view all the answers

What is the primary function of the thymus in the lymphatic system?

<p>Maturation of T cells (A)</p> Signup and view all the answers

What is histamine's primary function in the immune response?

<p>To increase the permeability of capillaries and cause vasodilation (A)</p> Signup and view all the answers

What percentage of white blood cells do lymphocytes typically constitute?

<p>20-40% (A)</p> Signup and view all the answers

Which type of lymphatic tissue is described as the first layer of defense?

<p>Tonsils (D)</p> Signup and view all the answers

What occurs to B-lymphocytes when they become activated?

<p>They develop into plasma cells that produce antibodies (D)</p> Signup and view all the answers

What happens to the thymus size during childhood?

<p>It increases in size (D)</p> Signup and view all the answers

What is the primary role of macrophages in the lymphatic system?

<p>Phagocytizing old red blood cells and platelets (B)</p> Signup and view all the answers

Where are lymphocytes primarily found?

<p>Mucosa-associated lymph tissue (MALT) (A)</p> Signup and view all the answers

The invaginated outer edges of tonsils form structures called:

<p>Crypts (B)</p> Signup and view all the answers

Which statement regarding the thymus is correct?

<p>It is involved in T cell maturation (C)</p> Signup and view all the answers

Which area does MALT primarily monitor for immune responses?

<p>Walls of respiratory and gastrointestinal tracts (B)</p> Signup and view all the answers

What is the primary function of arteries?

<p>Carry oxygenated blood away from the heart (D)</p> Signup and view all the answers

How does the tunica media contribute to the function of arteries?

<p>By regulating blood flow and withstanding pressure (D)</p> Signup and view all the answers

Which statement accurately describes arterioles?

<p>They are small branches of arteries that regulate blood flow (D)</p> Signup and view all the answers

What type of layer is present in capillaries and what is its function?

<p>Single layer of endothelial cells to allow diffusion (D)</p> Signup and view all the answers

What distinguishes veins from arteries?

<p>Veins have valves to prevent backflow (D)</p> Signup and view all the answers

What is the role of the tunica externa in veins?

<p>Provide structural support and elasticity (B)</p> Signup and view all the answers

What is the main function of venules in the circulatory system?

<p>Collect blood from capillaries and transport it to larger veins (C)</p> Signup and view all the answers

Which layer is absent in capillaries and why?

<p>Tunica media, because they do not need to dilate (A)</p> Signup and view all the answers

What is the primary function of conducting arteries?

<p>Withstand and reduce blood pressure fluctuations (A)</p> Signup and view all the answers

Which type of capillary is characterized by its many pores and is commonly found in endocrine glands?

<p>Fenestrated capillary (D)</p> Signup and view all the answers

How do skeletal muscles and valves work together to promote venous circulation?

<p>Push blood through the veins and prevent back flow (D)</p> Signup and view all the answers

When do new blood vessels typically form in an adult?

<p>Throughout life (B)</p> Signup and view all the answers

What changes are commonly associated with aging in blood vessels?

<p>Varicose veins and atherosclerosis (C)</p> Signup and view all the answers

What is the role of the precapillary sphincter in blood circulation?

<p>Regulate blood flow into capillary beds (D)</p> Signup and view all the answers

What is the primary route of the systemic circulation?

<p>Left heart to arteries to body tissues to veins to right heart (A)</p> Signup and view all the answers

What characterizes sinusoid capillaries?

<p>Wide spaces and incomplete basement membranes (D)</p> Signup and view all the answers

What is the correct order of the cardiac conduction pathway?

<p>Sinoatrial node, Atrioventricular node, Atrioventricular bundle, Purkinje fibers (B)</p> Signup and view all the answers

Which of the following represents the correct sequence of events in the cardiac cycle?

<p>Atrial systole, early ventricular systole, late ventricular systole (C)</p> Signup and view all the answers

What is the primary germ cell layer from which the heart is derived?

<p>Mesoderm (A)</p> Signup and view all the answers

What is the main difference between adult and fetal circulation?

<p>Fetal circulation bypasses lungs and liver capillary beds (B)</p> Signup and view all the answers

During which phase does the ventricular pressure rise causing AV valves to close?

<p>Early ventricular systole (B)</p> Signup and view all the answers

Which structure directs blood from the umbilical vein to the right atrium in fetal circulation?

<p>Ductus venosus (D)</p> Signup and view all the answers

In which phase does the atrial pressure rise, causing the AV valves to open?

<p>Late ventricular diastole (D)</p> Signup and view all the answers

What is the definition of systole in relation to heart chambers?

<p>Contraction of a heart chamber (A)</p> Signup and view all the answers

Flashcards

RBC Shape

Biconcave disks.

RBC Intracellular Structure

No nucleus or organelles; flexible plasma membrane.

RBC Function

Gas transportation; large surface area for rapid gas exchange; carries oxygen using hemoglobin.

Hemoglobin Structure

Red pigmented protein with 4 heme groups; each heme holds iron that binds oxygen.

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Oxyhemoglobin

Hemoglobin bound to oxygen.

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Deoxyhemoglobin

Hemoglobin after oxygen delivery to tissues.

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WBC Function

Fights infections, allergies, and inflammation;

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Leukocytosis

High WBC count, usually a response to infection or inflammation.

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Cardiac Cycle

The sequence of events in the heart during one complete heartbeat.

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Systole

Contraction phase of the heart chamber.

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Diastole

Relaxation phase of the heart chamber.

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Atrial Systole

Atrial contraction, pushing blood into the ventricles.

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Fetal Circulation

Blood circulation in an unborn fetus, adapting from maternal blood supply.

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Ductus Venosus

Fetal vessel bypassing liver.

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Foramen Ovale

Fetal shunt bypassing the lungs.

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Ductus Arteriosus

Fetal vessel bypassing the lungs.

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Leukopenia

Abnormally low white blood cell count, a serious disorder.

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Neutrophils

50-70% of WBCs, fight bacteria by engulfing them.

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Eosinophils

1-4% of WBCs, target parasites and allergens.

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Basophils

0.5-1% of WBCs, release histamine and heparin in inflammatory/allergic reactions.

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Lymphocytes

20-40% of WBCs, crucial for immune response, fight viruses and produce antibodies (B cells).

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Histamine

Dilates blood vessels and increases capillary permeability during inflammation.

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Heparin

An anticoagulant that prevents blood clotting.

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Causes of Leukopenia

Infection, leukemia, or toxins damaging bone marrow.

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Artery Function

Carry oxygenated blood away from the heart

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Artery Tunica Interna

Smooth lining reducing blood flow resistance

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Artery Tunica Media

Thick, muscular layer with elastic fibers for pressure and flow regulation

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Arteriole Function

Control blood flow into capillaries

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Capillary Function

Gas, nutrient, and waste exchange between blood and tissues

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Vein Function

Return deoxygenated blood to the heart

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Vein Valves

Prevent backflow of blood

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Conducting vs. Distributing Arteries

Conducting arteries are large and elastic, whereas distributing arteries are smaller and more muscular. This difference reflects their role in carrying and controlling blood flow, respectively.

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Conducting Arteries

Largest arteries, withstand and reduce large blood pressure fluctuations. Walls have lots of elastic fibers, less smooth muscle.

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Distributing Arteries

Medium-sized arteries, control blood supply via vasoconstriction/vasodilation. Walls contain more smooth muscle, less elastic fibers.

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Anastomoses

Connections between blood vessels, providing alternate paths for blood flow.

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Capillary Types

Different capillary types allow for selective movement of substances into and out of blood. Continuous, fenestrated, and sinusoidal.

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Venous Circulation

Dependent on valves, and skeletal muscle contractions to counteract lower blood pressure for proper function.

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Blood Reservoir

Veins can expand to hold extra blood, especially when not needed in some areas.

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New Blood Vessel Formation

Angiogenesis occurs throughout life, to improve blood flow.

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Systemic Circulation

The circulatory route from the heart to the body and back to the heart.

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Thymus (primary)

Primary lymphatic organ where T cells mature. Located anterior to the heart, in the mediastinum.

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Reservoir of RBCs and platelets

A store of red blood cells and platelets. Macrophages rid old or damaged cells from this reservoir.

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MALT

Mucosa-associated lymphoid tissue. Lymph tissue in walls of respiratory, gastrointestinal, genital, urinary tracts.

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Tonsils

Lymphoid structures in the throat, first line of defense against ingested or inhaled antigens.

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Macrophages

Immune cells that remove old and damaged red blood cells and platelets from the reservoir.

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Primary Lymphatic Organ

An organ where immune cells are produced or mature. An example is the thymus.

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Lymphocytes location (MALT)

Lymphocytes reside in mucous membranes and are exposed to antigens.

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Tonsil Structure (crypts)

Invaginated outer edges of tonsils that trap and identify potential threats.

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Study Notes

Circulatory System

  • The heart pumps blood, delivering oxygen and removing waste products.
  • Arteries carry oxygenated blood away from the heart; pulmonary arteries carry deoxygenated blood to the lungs.
  • Capillaries facilitate gas exchange.
  • Pulmonary veins carry oxygenated blood to the heart; systemic veins carry deoxygenated blood back to the heart.
  • The lungs perform gas exchange.

Blood Functions

  • Transportation: Blood carries gases, hormones, nutrients, and waste products.
  • Protection: White blood cells (WBCs) and antibodies defend against pathogens; platelets and proteins are involved in clotting.
  • Regulation: Maintaining pH, fluid balance, and temperature.

Bodily Fluids

  • Blood: Found throughout the body, consisting of plasma and formed elements (RBCs, WBCs, and platelets)
    • Plasma: fluid matrix (no cells).
    • Formed elements: 45% of total blood volume.
    • Buffy coat: Leukocytes and platelets (less than 1%).
    • Hematocrit: Percentage of volume of all formed elements (45%).
  • Plasma solutes: Ions, nutrients, gases, and waste (1%).
  • Interstitial fluid: Derived from plasma, found in capillaries.
  • Lymph: Found in lymph vessels, ground substance of blood without clotting proteins.
  • Serum: Interstitial fluid without clotting proteins.

Blood Cell Types

  • Formed elements (Blood Cells):
    • RBCs (Red Blood Cells): 55% of whole blood. Biconcave disks, no nucleus, and very flexible plasma membrane.
      • Functions: Gas transportation (oxygen binding). ATP generation.
    • Hemoglobin (color red pigment with 4 heme groups): Each heme has iron binding oxygen, for oxygen transport. Oxygen loading (oxygen binding) occurs in the lungs.
    • Oxyhemoglobin: bright red, hemoglobin bonded with oxygen.
    • Deoxyhemoglobin: dark red, hemoglobin not bonded with oxygen
    • WBCs (White Blood Cells): Less than 1%.
    • Platelets: Less than 1%. Involved in blood clotting.
    • For neutrophil type: 50-70 %, phagocytize infectious pathogens, nucleus segmented and varied in 2-5 lobes, granules appear light purple.
    • For eosinophil type: 1-4 %, attack parasitic worms, phagocytize antigen-antibody complexes, bilobed nucleus, granules stain reddish-pink.
    • For basophil type: .5-1 %, release histamine and heparin during inflammatory or allergic reactions, bi-lobed nuclei, granules stain blue-violet, occlude nucleus and cytoplasm.
  • Others:
    • Lymphocytes (20-40%): Orchestrate immune responses, attack viruses/infected cells, produce antibodies (B cells), and natural killer cells.
    • Monocytes (2-8%): Exit blood vessels and become macrophages, phagocytize pathogens.

Heart Anatomy and Function

  • Apex: Pointed end projecting inferolaterally.
  • Base: Superior portion where major vessels attach.
  • Fibrous pericardium: Surrounds the heart, fibrous sac lined with serous membrane, protects and anchors the heart, prevents blood from overflowing into the heart, provides friction-free environment.
  • Serous pericardium: Parietal layer lines the inside of fibrous pericardium, visceral layer covers external surface of heart.
  • Endocardium: Simple squamous epithelium and areolar connective tissue.
  • Atria: Right atrium receives deoxygenated blood from superior and inferior vena cava and right and left pulmonary veins. Left atrium receives oxygenated blood from the lungs.
  • Ventricles: Right ventricle pumps deoxygenated blood to the lungs, left ventricle pumps oxygenated blood to the body.

Blood Vessels

  • Arteries: Carry oxygenated blood away from the heart, thick and muscular walls with smooth and elastic fibers to withstand high pressure, regulate blood flow. Tunica interna, tunica media, tunica externa.
  • Arterioles: Small branches of arteries that lead to capillaries, thinner layer allowing blood flow and able to control blood flow, pressure through contraction.
  • Capillaries: Sites of gas and nutrient exchange, single layer of endothelial cells.
  • Venules: Collect blood from capillaries and transport to veins. Thin layer similar to capillaries to provide support & Minimal construction.
  • Veins: Return deoxygenated blood to the heart, contain valves to prevent backflow, lower pressure than arteries, structural support and elasticity.

Lymphatic System

  • Functions: Returns interstitial fluid to blood circulation; monitors interstitial fluid; mounts immune responses.
  • Lymphatic capillaries: Closed-end tubes that collect interstitial fluid, and lipids (chyle in intestinal tract).
  • Lymph nodes: Filter lymph; site of immune responses.

Lung Anatomy and Functions

  • Respiratory Membrane: Alveolar simple squamous epithelial cells wall. Capillary endothelial walls.
  • Alveoli: Sites of gas exchange in the lungs. Surfactant to prevent sticking.
  • Pleura: Lining surrounding lungs to reduce friction. Parietal layer (thoracic wall); visceral layer (lung surface).

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