Circulatory System Overview
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Questions and Answers

What is the primary function of the afferent branchial arteries in the cardiovascular system of vertebrates?

  • Exits gills
  • Deliver oxygenated blood to the body
  • Transport blood from the heart
  • Deliver low-O2 blood to gills (correct)

    • The basic pattern of the cardiovascular system in vertebrates is found only in advanced species.

    False

    What structures do the paired dorsal aortae develop from in vertebrates?

    Mesoderm

    The _____ arteries transport blood to the head and brain from the gills.

    <p>carotid</p> Signup and view all the answers

    Match the following elements of the cardiovascular system with their descriptions:

    <p>Afferent branchial arteries = Deliver low-O2 blood to gills Efferent branchial arteries = Exit blood from gills Internal carotids = Supply blood to the brain External carotids = Supply blood to the head</p> Signup and view all the answers

    What happens to blood vessels during vasoconstriction?

    <p>Lumen narrows.</p> Signup and view all the answers

    Capillaries have thicker walls than arteries.

    <p>False</p> Signup and view all the answers

    What term describes the hardening of arteries due to loss of elasticity?

    <p>Arteriosclerosis</p> Signup and view all the answers

    The process of adjusting blood flow to active tissues is known as __________.

    <p>microcirculation</p> Signup and view all the answers

    Match the following components of the cardiovascular system with their primary characteristics:

    <p>Arteries = Carry blood away from the heart and have thick walls with elastin Veins = Carry blood back to the heart and have thinner walls Capillaries = Site of exchange for gases and nutrients Arterioles = Small blood vessels that regulate blood flow</p> Signup and view all the answers

    Which of the following statements about diastolic pressure is true?

    <p>It is the pressure measured between heart contractions.</p> Signup and view all the answers

    The primary function of capillaries is to transport blood quickly through the body.

    <p>False</p> Signup and view all the answers

    What is the role of precapillary sphincters in the microcirculation?

    <p>Regulate blood flow to capillary beds</p> Signup and view all the answers

    What is the primary function of veins in the cardiovascular system?

    <p>Store blood and prevent pooling</p> Signup and view all the answers

    Blood in a shark's circulatory system is primarily high in oxygen.

    <p>False</p> Signup and view all the answers

    What type of circulation system do mammals and birds have?

    <p>Double Circulation</p> Signup and view all the answers

    Veins have _______ walls and contain one-way valves to prevent backflow.

    <p>thinner</p> Signup and view all the answers

    Match the following blood vessels with their characteristics:

    <p>Arteries = Thick, elastic walls for high pressure Veins = Thinner walls with one-way valves Capillaries = Site of nutrient and gas exchange Arterioles = Regulate blood flow into capillaries</p> Signup and view all the answers

    What role does skeletal muscle activity play in the cardiovascular system?

    <p>It facilitates blood movement through veins.</p> Signup and view all the answers

    In double circulation, blood moves through the heart only once for each complete circuit.

    <p>False</p> Signup and view all the answers

    Functionally, how do veins prevent pooling of blood?

    <p>Through vasoconstriction and one-way valves.</p> Signup and view all the answers

    Which vertebrates have a renal portal system?

    <p>All vertebrates except mammals</p> Signup and view all the answers

    Mammals possess a renal portal vein connecting caudal blood to the kidney.

    <p>False</p> Signup and view all the answers

    What structure acts as the pacemaker in the heart?

    <p>SA Node</p> Signup and view all the answers

    The renal portal system connects blood from the ______ to the kidney.

    <p>tail</p> Signup and view all the answers

    What connects the cells of cardiac muscle to ensure coordinated contraction?

    <p>Intercalated disks</p> Signup and view all the answers

    Match the following structures to their respective functions in the heart:

    <p>SA Node = Acts as pacemaker AV Node = Coordinates atrial and ventricular contraction Purkinje fibers = Transmits impulses throughout the ventricles Accessory hearts = Found in hagfish and assist in circulation</p> Signup and view all the answers

    The contraction of cardiac muscle is solely dependent on nervous system control.

    <p>False</p> Signup and view all the answers

    What are the two factors that likely favored the development of the renal portal system in vertebrates?

    <p>Active tail/axial muscles and low pressure of venous blood</p> Signup and view all the answers

    What effect does greater stretching of cardiac muscle have on contraction strength?

    <p>It increases contraction strength.</p> Signup and view all the answers

    The heart of a fish has a complex structure with four distinct chambers.

    <p>False</p> Signup and view all the answers

    What is the main function of the conus arteriosus in a fish heart?

    <p>To help pump blood out of the heart.</p> Signup and view all the answers

    The heart of a lungfish features a _____ valve in the conus arteriosus to prevent loss of oxygen to water.

    <p>spiral</p> Signup and view all the answers

    Match the following components of the fish heart to their descriptions:

    <p>Sinus venosus = Receives deoxygenated blood from veins Atrium = Thin-walled chamber connected to the ventricle Ventricle = Primary pumping chamber of the heart Conus arteriosus = Contains conal valves to regulate blood flow</p> Signup and view all the answers

    What modifier in the lungfish heart signifies a shift to double circulation?

    <p>Atrioventricular plug</p> Signup and view all the answers

    All amphibians have the same heart structure as lungfish.

    <p>False</p> Signup and view all the answers

    What is the aspiration effect in the context of the fish heart?

    <p>It is the negative pressure in the heart that pulls blood into the sinus venosus and atrium.</p> Signup and view all the answers

    What is the primary role of the umbilical vein in the fetal circulation?

    <p>Both A and C</p> Signup and view all the answers

    The ductus arteriosus closes after birth, becoming the fossa ovalis.

    <p>False</p> Signup and view all the answers

    What is the remnant of the ductus venosus in a neonate?

    <p>Round ligament of the liver</p> Signup and view all the answers

    The __________ is the opening between the right and left atria in the fetal heart.

    <p>foramen ovale</p> Signup and view all the answers

    Match the fetal structure with its postnatal counterpart:

    <p>Umbilical vein = Round ligament of liver Ductus venosus = Round ligament of liver Foramen ovale = Fossa ovalis Ductus arteriosus = Ligamentum arteriosum Umbilical arteries = Round ligament of urinary bladder</p> Signup and view all the answers

    What happens to blood flow in the neonate's lungs after the first breath?

    <p>Blood flow to the lungs increases</p> Signup and view all the answers

    The umbilical arteries carry oxygen-rich blood from the fetus to the placenta.

    <p>False</p> Signup and view all the answers

    During fetal circulation, blood that enters the right atrium mostly goes directly to the __________ via the foramen ovale.

    <p>left atrium</p> Signup and view all the answers

    Study Notes

    Circulatory System

    • Functions: Transports gases between sites of external and internal respiration.
    • Also transports: products of digestion, hormones, waste products, cells and chemicals of the immune system, and heat.

    Two Vascular Systems

      1. Cardiovascular system: blood, vessels, and heart.
      1. Lymphatic system: lymphatic vessels and lymph.

    The Lymphatic System

    • Lymphatic vessels and lymph.
    • Cervical lymph nodes.
    • Lymphatics of the mammary gland.
    • Cisterna chyli.
    • Lumbar lymph nodes.
    • Lymphatics of the upper limb.
    • Pelvic lymph nodes.
    • Lymphatics of the lower limb.
    • Inguinal lymph nodes.
    • Thoracic duct.
    • Thymus.
    • Axillary lymph nodes.
    • Spleen.
    • etc...

    Cardiovascular System

    • Formed elements of blood:

      • Blood plasma: fluid component.
      • Erythrocytes (red blood cells): carry hemoglobin.
      • Leukocytes (white blood cells): immune response.
      • Thrombocytes (platelets): important for clot formation.
      • Plasma is 95% water, proteins, glucose, clotting agents, electrolytes...

    • Do all vertebrates have red blood cells and hemoglobin?: No.

      • 16 species of crocodile icefish do not have red blood cells or hemoglobin.
      • However, they have a larger heart.
      • They have no myoglobin in skeletal muscles.
      • They can live in waters down to 28°F with antifreeze proteins.
      • They also have no swim bladders, low-density bone, and low metabolism.

    • Does the blood passing through a shark heart differ from that passing through a dog's (or pigeon's) heart?: Yes.

      • Shark: all low-O2 blood, one stream.
      • Dog: 2 streams (one low-O2, the other high-O2).

    • Arteries vs Veins:

      • Arteries: take blood away from heart.
      • Veins: bring blood back to heart.

    • Pulmonary arteries (mammals), blood to lungs, low O2.

    • Ventral aorta (shark), blood to gills, low O2.

    • Blood vessels:

      • Highest blood pressures in arteries, and walls with high elastin fiber content, absorbing sudden energy surges (pulse), and stretching.
      • Elastic recoil moves blood along smoothly.
      • Arteriosclerosis, losing elasticity due to deposits, and potentially causing heart to work harder (unable to recoil) or causing smaller vessels to rupture.

    • Microcirculation:

      • Arterioles-capillary beds-venules.
      • Arterioles & Venules: smooth muscle and a bit of elastin.
      • Capillaries: site of exchange.
      • Thin walls, with mostly epithelium, for gas, nutrient, waste, water, ion, and heat transport.

    • Controls arterial flow:

      • Vasoconstriction/Vasodilation: contraction/relaxation of smooth muscles to narrow/expand lumen.
      • Capillaries represent huge volume.
      • Danger if all open: shock/trauma = vasodilation, drop in blood pressure.
      • Epinephrine (adrenaline) - vasoconstriction.

    • Precapillary sphincters:

      • Regulate flow to capillary beds.
      • Adjust to activity levels.
      • Under nervous + hormonal control.

    • Capillary Beds:

      • Overlap, redundancy.
      • Tissues with multiple beds.
      • With sphincters: adjust blood flow to activity level.

    • Microcirculation:

      • Blood to active tissues.
      • Thanksgiving: 'food coma'.
      • Running w/o digesting: ischemia.
      • Heat transfer: cooling - blood to skin, e.g., Jackrabbit ears.
      • Ectotherm: adjusting behavior (warming vs cooling).

    • Veins:

      • Large volume.
      • Thinner walls.
      • Little elasticity, 'baggy'.
      • Reserve volume: up to 70% of blood may be in veins at one time.

    • Veins (blood flow product):

      • One-way valves: prevent backflow.
      • Skeletal muscle: forces blood through system.

    • Activity moves more blood from reserve into arterial vessels.

    • With long necks:

      • Cardiovascular system adjusts with head movements to maintain flow/pressure.
      • Aortic pressure adjusts with head movements.
      • Pooling prevented likely by vasoconstriction (raised) and vasodilation (lowered).
      • Blood affects kidneys.

    • Circulation systems:

      • Single circulation: blood passes through heart once during complete circuit (e.g., shark, perch).
      • Double circulation: blood passes through heart twice during complete circuit (e.g., pigeon, mammals).

    • Cardiovascular system:

      • Does blood passing through a shark heart differ from that passing through a dog?: yes
        • Sharks: all low-O2 blood, one stream.
        • Dogs: 2 streams (one low-O2 and one high-O2).

    • Renovation:

      • Evolution through modifications of previously existing structures.

    • Blood vessels: formed from mesoderm, formed early (48 hours in chick).

    • Arterial vessels: follow similar embryonic pathways; diverge through late stages of development.

      • Single ventral aorta from heart.
      • Six pairs of branchial arteries.
      • Paired dorsal aortae.
      • Basic pattern, embryos, sharks, most fish.
      • Each arch with afferent (& efferent) branchial arteries.

    • Lymphatic System

      • 2nd part of the circulatory system with its own vessels, tissues, and fluid.
      • 3 functions
        • Recapture fluid lost from cardiovascular system (interstitial fluid).
        • Absorb fats.
        • Remove and destroy harmful invaders.

    • Lymph:

      • Mostly water with electrolytes and proteins
      • Capillaries leaky
      • Hydrostatic pressure pushes fluid out.
      • Osmotic pressure helps recapture.
      • 10% remains in the tissues

    • Lymphatic vessels:

      • Walls like veins, little muscle, one-way valves.
      • Rely on body movements: breathing, muscle contraction, arteries.
      • Some vertebrates have smooth muscle pumps.

    • Lacteals: special vessels around digestive tract to absorb lipids.

    • Lymphatic tissue: free cells - leukocytes (Lymphocytes - produce antibodies, and Macrophages - attack foreign bodies), lymph nodes

      • Located along lymph vessels.
      • Fluid percolates through.
      • Lymph nodes swell with infection (bubonic plague).
      • Cancer treatment may involve examination and/or removal of lymph nodes if necessary.

    • Venous Systems

      • Veins: Very variable in arrangement within species.
      • Functions
        • Drain body tissues (systemic, jugular)
        • Drain lungs (pulmonary veins)
        • Hepatic portal system (extension from the lungs)
        • Renal portal system (extension from the lungs)
      • Vitelline veins
        • First to form in embryos
        • Drain from yolk, gut, and into your heart.
        • Bring nutrients from yolk.
        • Brings O2 rich blood in amniotes
        • Gets incorporated into the liver and hepatic portal system.
      • Primitive
        • Paired anterior/posterior cardinal veins.
        • Paired common cardinal veins.

    • Portal Systems

      • Vascular channel; begins in one set of capillaries, runs to another, without going through the heart.
      • Hepatic
        • All vertebrates
        • Connects digestive tract to liver.
        • Transports nutrients to liver for storage and processing.
        • Transports toxic stuff to be destroyed.
      • Renal
        • All vertebrates except mammals.
        • Connects caudal blood (from tail) to kidney.
        • Subcardinal or renal vein drains kidneys.
        • Processed by kidney.

    • Heart

      • Hagfish: unusual in having accessory structures, initially a simple tubular structure, with four chambers in a row.
      • Heart rate under nervous & hormonal control.
      • Starling reflex: greater stretching of cardiac muscle increases contraction
      • Heart beat: contraction intrinsic to cardiac muscle: (intercalated disks connect cells and coordinate contractions).
      • SA node (sinoatrial node): Acts as a pacemaker, near right atrium.
      • Cardiac muscle cells that act neuron-like (AV node, Purkinje fibers)
      • Heart of a Lungfish: modified heart structures to allow switching between gill breathing and lung breathing
      • Heart of amphibians: similar to lungfish, with fully divided atria, undivided ventricle, trabeculae, and a spiral valve.
      • Hearts of birds and mammals: more straight-forward structure. 2 atria and 2 ventricles
      • Apnea (in diving birds and mammals); aerobic metabolism increases, microcirculation alters blood flow to needed organs/tissues.

    • Heart of reptiles

      • Complex and plumbing (3 aortae).
      • Accommodates apnea, time periods of non-breathing during submersion, hibernation/aestivation, and quiet periods.
      • Single ventricle but partially divided, with a shunt.
      • Muscular ridge separates cavum venosum and cavum pulmonale.
      • Can tune blood volume to the lungs.
        • Crocodile
          • Ventricles fully divided
          • Foramen of Panizza
            • Connects left and right systemic arches.
            • Shunts high-O2 blood when breathing to body
            • Limited use during apnea.

    • Heart Trivia

      • Entire blood goes through heart in one minute
      • Heart could empty a pool in a week
      • Last organ operated on
      • Broken heart (is it real?): Takotsubo Cardiomyopathy; a syndrome that causes your heart to change shape (emotionally stressful situations).

    • Heat transfer

      • Microcirculation moves blood to/away from skin.
        • With exercise or high environmental temps, blood shunted to skin for cooling.
      • Rete (adjacent networks of arteries and veins): Acts as heat block with countercurrent flow. Important in aquatic vertebrates (e.g., duck feet, dolphin fins).
      • Pampiniform plexus (sperm production): countercurrent heat exchange.
      • Carotid rete: Keeps brain from overheating. Blood returning from nose/turbinates passes by carotids and cools. (without in rabbits).

    • Major shifts in circulation at birth for placental mammals:

      • Umbilical vein: from placenta (high O2 + nutrients)
      • Ductus venosus
      • Foramen ovale
      • Ductus arteriosus
      • Umbilical arteries: to placenta (low O2).
      • Patent Foramen Ovale (PFO):
        • In ~ 25-33% of adults; foramen ovale never closes completely.
        • Pressure largely keeps closed, but some leakage
        • Increases risk of stroke, migraines, decompression illness, high altitude pulmonary edema (once considered unlikely).

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    Explore the essential functions and components of the circulatory system, including the cardiovascular and lymphatic systems. Understand how blood transports gases, hormones, and nutrients, as well as the role of various blood cells. This quiz provides insights into the anatomy and physiology of the circulatory system.

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