Circulatory System

Chapter 42

A. P. Biology

Liberty Senior High

Mr. Knowles

What’s the purpose of the cardiovascular system?

Do all organisms have one?

Unicellular Organisms

• Use simple diffusion for moving nutrients and oxygen into cell; wastes and carbon dioxide out of cell.

• Problem: Surface area – to – volume ratio; limits the size.

Phylum Nemotoda• Use a body cavity – to transport

materials to more distant cells.

• Not a true circulatory system.

• Problem: limited by size of organism or distance cells can be from body cavity.

Open and Closed Circulatory Systems

• More complex animals

–Have one of two types of circulatory systems: open or closed

• Both of these types of systems have three basic components

–A circulatory fluid (blood)

–A set of tubes (blood vessels)

–A muscular pump (the heart)

• In insects, other arthropods, and most molluscs:

– Blood bathes the organs directly in an open circulatory system

Heart

Hemolymph in sinusessurrounding ograns

Anterior vessel

Tubular heart

Lateral vessels

Ostia

(a) An open circulatory systemFigure 42.3a

Two Types of Circulatory Systems

• Open Circulatory System- no distinct circulating fluid, body fluid is the circulating fluid.

• Muscular pump pushes fluid through channels and spaces in body. Fluid drains back into central cavity.

• Arthropods (Insects, Crustaceans)

• In a closed circulatory system:

– Blood is confined to vessels and is distinct from the interstitial fluid

Figure 42.3b

Interstitialfluid

Heart

Small branch vessels in each organ

Dorsal vessel(main heart)

Ventral vesselsAuxiliary hearts

(b) A closed circulatory system

Two Types of Circulatory Systems

• Closed Circulatory System- circulating fluid is enclosed within blood vessels; does not mix with other body fluids.

• Materials diffuse through vessel walls to tissues.

• Examples: Annelids and all vertebrates.

PulmonaryPulmonaryCircuitCircuit

Systemic Systemic CircuitCircuit

Two Major Circuits• Pulmonary Circuit: carries

blood to & from the gas exchange surfaces of the lungs.

• Systemic Circuit: which transports blood to & from the rest of the body.

Why we need a cardiovascular system!

• Human embryos before 3 weeks are so small, materials are transported by simple diffusion.

• At third week (few mms in length), heart begins beating- first organ system to function.

• Supplies nutrients to all 75 trillion cells in the body.

Evolution of Vertebrate Heart

Recall what the human heart looks like.

Why a heart?• More active lifestyle: change

from filter- feeding to active prey capture; requires more efficient respiration and circulation.

• Invasion of land: change in respiration system and endothermy.

Early Chordates• Heart = simple tube heart;

thicker muscular artery that contracted.

• Was a peristaltic pump. • Problem: blood is pushed in

both directions; inefficient.• Ex. Lancelets.

Fish Heart• True chambered-pump heart.• A tube with four consecutive chambers.

– Sinus venosus- collects blood from body.– Atrium- receives blood from the S.V.– Ventricle- pumping chamber.– Conus arteriosus- smaller, elongated pump.

• “Two-chambered” heart in peristaltic sequence; 1 atrium, 1 ventricle.

• Fig. 46.36

Fishes

• A fish heart has two main chambers

– One ventricle and one atrium.

• Blood pumped from the ventricle

– Travels to the gills, where it picks up O2 and disposes of CO2

Fish Heart• Blood goes from Heart Gills

Becomes Oxygenated Arteries to Body Tissues Veins Return to Heart

• Benefit: peripheral tissues receive fully oxygenated blood directly from gills.

• Problem: blood loses pressure from gills to body; no pulmonary circulation.

Amphibian Heart• Fully terrestrial lungs require a

pulmonary circuit.• Uses pulmonary arteries/veins to

oxygenate blood and return to heart for repumping.

• Higher pressure out to peripheral tissues.• “Three-chambered” heart; 2 Atria, 1

ventricle.

Amphibians• Frogs and other amphibians:

– Have a three-chambered heart, with two atria and one ventricle.

• The ventricle pumps blood into a forked artery.

– That splits the ventricle’s output into the pulmocutaneous circuit and the systemic circuit.

Amphibian Heart• Problem: Oxygenated and

deoxygenated blood mix in ventricle.

• Heart pumps out a mixture of oxy- and deoxygenated blood to peripheral tissues.

• Inefficient systemic circulation.

Reptile Heart• Developed a partial septum (wall)

between the ventricle.• Partially separates oxy- and

deoxygenated blood.• Benefit: More efficient circulation;

more active. • Problem: Still a three-chambered

heart with some mixing; incomplete separation.

Reptiles (Except Crocodilians)

• Reptiles have double circulation:

– With a pulmonary circuit (lungs) and a systemic circuit.

• Turtles, snakes, and lizards:

– Have a three-chambered heart

Enter the Crocodiles!• Have complete separation of

ventricles.• First Four-chambered heart that

separates oxy- and deoxygenated blood.

• Completely separate pulmonary and systemic circuits.

• Increased efficiency and more active.

A Very Active Saltwater Crocodile!

Mammal and Bird Hearts• True Four-chambered hearts- separate

systemic and pulmonary circuits.

• Can repump blood to body after return from lungs without mixing oxy- and deoxygenated blood.

• Double Pump: Right side = pulmonary circuit and Left Side = systemic circuit.

• Greater efficiency = higher metabolic rate, transport of heat and endothermy.

• The mammalian cardiovascular system

Pulmonary vein

Right atrium

Right ventricle

Posteriorvena cava

Capillaries ofabdominal organsand hind limbs

Aorta

Left ventricle

Left atriumPulmonary vein

Pulmonaryartery

Capillariesof left lung

Capillaries ofhead and forelimbs

Anteriorvena cava

Pulmonaryartery

Capillariesof right lung

Aorta

Figure 42.5

110

11

5

4

6

2

9

3 3

7

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The Mammalian Heart: A Closer Look

Figure 42.6

Aorta

Pulmonaryveins

Semilunarvalve

Atrioventricularvalve

Left ventricleRight ventricle

Anterior vena cava

Pulmonary artery

Semilunarvalve

Atrioventricularvalve

Posterior vena cava

Pulmonaryveins

Right atrium

Pulmonaryartery

Leftatrium

FISHES AMPHIBIANS REPTILES (EXCEPT CROCS) MAMMALS AND BIRDS

Systemic capillaries Systemic capillaries Systemic capillaries Systemic capillaries

Lung capillaries Lung capillariesLung and skin capillariesGill capillaries

Right Left Right Left Right Left

Systemic circuit

Systemic circuit

Pulmocutaneouscircuit

Pulmonarycircuit

Pulmonarycircuit

SystemiccirculationVein

Atrium (A)

Heart:ventricle (V)

ArteryGill

circulation

A

V VV VV

A A A AALeft Systemicaorta

Right systemicaorta

Figure 42.4

• Vertebrate circulatory systems

What is the cardiovascular system?

Three parts:• Blood – a circulating fluid.• Heart – a pump. • Blood vessels – the

conducting pipes.

Cardiovascular Lymphatic Systems • Fluid leaves the vessel and enters the tissues-

interstitial fluid.• Eventually returns to the vessels.• Lymphatic system has its own vessels.• Used to transport antibodies, white blood cells,

and monitor for infection and cancer.• Cardiovascular + Lymphatic = Circulatory

System.

• The velocity of blood flow varies in the circulatory system:– And is slowest in the capillary beds as a result of the high

resistance and large total cross-sectional area.

Figure 42.11

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• Two mechanisms:–Regulate the distribution of blood in

capillary beds.• In one mechanism-

–Contraction of the smooth muscle layer in the wall of an arteriole constricts the vessel.

• In a second mechanism:– Precapillary sphincters control the flow of blood

between arterioles and venules.

Figure 42.13 a–c

Precapillary sphincters Thoroughfarechannel

ArterioleCapillaries

Venule(a) Sphincters relaxed

(b) Sphincters contractedVenuleArteriole

(c) Capillaries and larger vessels (SEM)

20 m

Marine Mammals

• Limit heat loss by countercurrent flow- veins run parallel to an artery and carry heat back to core before arterial blood circulates to body’s surface.

• Walruses, seals, killer whales (Fig. 46.23)

What is blood?

• Specialized connective tissue with cells in a fluid matrix.

Functions of the Blood• Transport dissolved gases, nutrients,

hormones, and metabolic wastes.• Regulation of the pH and electrolytes of

interstitial fluid. Neutralizes the acids created by metabolism (lactic acid).

• Restricts fluid losses through damaged vessels or at injury sites- blood clots.

Functions of the Blood• Defense against toxins and pathogens-

transports white blood cells that migrate into tissue to fight infection and remove debris. Also, deliver antibodies.

• Stabilize body temperature- absorbs heat from active muscles and distributes to other tissues. Also brings heat to the surface of the skin to lose heat.

Composition of Blood• It is a fluid connective tissue with

an extracellular matrix- plasma + formed elements (cells and cell fragments) = whole blood.

• Plasma + Formed Elements = Whole Blood.

Whole Blood After Centrifugation

Red Blood Cells

White Blood Cells “Buffy Coat”

Plasma

Whole Blood

Centrifuge and

Separate

Formed Elements

37-54%

Plasma

46-63%

Plasma

92 % Water

7 % Plasma Proteins

1 % Electrolytes and other Solutes

Plasma- The Fluid of Life!• Plasma = Plasma Proteins + a Ground

Substance (Serum).• Plasma Proteins:

Albumin- transport fatty acids, maintain isotonic solution.Globulin- immunoglobulin (antibodies).Fibrinogen- form blood clots; becomes fibrin- an insoluble protein.

Plasma

Fibrinogen

Serum Albumin

Globulin

Plasma- The Fluid of Life!• Plasma that has been

allowed to clot will lose its fibrin and other salts like Ca+2.

• Plasma without its fibrin – Serum.

Formed Elements• Formed Elements = Blood Cells + Fragments

suspended in the plasma.• Erythrocytes (Red Blood Cells) – most

abundant (99.9% of all cells); transport of oxygen and carbon dioxide.

• Leukocytes (White Blood Cells) – body’s defense cells. (0.1% of cells).

• Thrombocytes (Platelets) – small, membrane- bound packets of cytoplasm that contain enzymes for blood clot formation.

Erythrocyte

A Normal Blood Smear

Collecting and Analysis of Blood• Blood usually collected at a vein-venipuncture.• Venipuncture- veins are easy to locate, walls of

vein are thinner, pressure is lower heals easier.• Peripheral capillaries- tip of finger, earlobe;

oozing small drop for blood smear.• Arterial Puncture- check for efficiency of gas

exchange.

Properties of Blood• Temperature- 38° C or 100.4°F.

• Viscosity- has a great deal of dissolved proteins in plasma more viscous than water.

• pH – 7.35-7.45; slightly alkaline.

Erythrocytes (RBCs)• “erythros”- red; “cyte”- cell.• RBCs are the most abundant blood cell (99.9%).

25 trillion in average adult. Takes ~ 1 min. to travel circuit.

• Hematocrit- percentage of formed elements in a sample of whole blood. # of cells / microliter of whole blood.

• Has a red pigment-hemoglobin- gives whole blood its color.

RBCs Structure and Function• Highly specialized cell to transport

gases.

• Cell structure is a biconcave disc.

EM of RBCs

RBCs Structure and Function• Shape provides the RBC with a large surface

area.• Exchange of O2 with the surrounding plasma

must be quick; larger surface area faster the exchange.

• Total surface of all RBCs is 3800 m2 compared to 1.9 m2 of the whole human body.

RBCs Structure and Function• Biconcave shape allows them to form

stacks (dinner plates) – rouleaux inside narrow blood vessels.

• Rouleaux permit the cells to pass through blood vessels without bumping along the walls.

• Do not form logjams or clogs in the narrow capillary.

Rouleaux in a Blood Smear

Rouleaux in Bone Marrow

RBCs Structure and Function• Biconcave shape allows the

RBCs to bend and flex when entering capillaries.

• May pass through capillaries ½ the RBC’s diameter.

RBC’s are Highly Specialized Cells

• Have lost all organelles- lack nuclei, mitochondria, and ribosomes.

• Lost these structures to allow more space for hemoglobin and oxygen transport.

• Downside: RBCs unable to divide or repair themselves. Made in bone marrow.

• Short lifespan- 120 days and then must be broken down.

Hemoglobin (Hb)

• Accounts for 95% of proteins inside the RBC.

• 280 million Hbs in each RBC.• Hb binds to and transports O2

and CO2.

Hb Molecule• Each Hb molecule = four protein chains = 2

alpha chains + 2 beta chains of polypeptides.• Each chain is a globular subunit and has a

heme group.• Heme – a porphyrin which is a ring compound

with an iron in the center.• Iron has a + charge and can bind to O2

(negative).

Hb Molecule

• When hemoglobin binds to O2 – it becomes oxyhemoglobin.

• Very weak interaction; easy to separate.• Fetus uses a fetal hemoglobin- more

readily binds to O2 for more efficient uptake from mother’s RBCs.

Hb Molecule• Alpha and Beta chains bind to CO2

at other sites and transport to lungs. • If hematocrit is low or the amount

of Hb in RBCs is low than normal activity cannot be sustained in tissue- anemia.

Sickle Cell Anemia• Mutations in the beta chains of the Hb

molecule.• When the blood contains abundant O2, the Hb and

RBCs are normal.• But when the defective Hb loses its O2,

neighboring Hb molecules interact and change the shape of the cell- curved and stiff.

• Cannot form rouleaux and may form clots.

Sickle Cell Mutation

Sickle Cell Mutation

Sickle Cell Anemia

Iron-Deficiency Anemia

Malaria in an RBC

Leukocytes (WBCs)• General Properties:

1. Help defend against pathogens, toxins, and damaged cells.2. They have nuclei and other organelles.3. Are made in bone marrow, thymus, spleen, and other lymphatic tissue.

Two Major Groups of WBCs1. Granulocytes- WBCs with

darkly-staining vesicles and lysosomes inside.

a. Neutrophils

b. Eosinophils

c. Basophils

Two Major Groups of WBCs

2. Agranulocytes- do not stain darkly on their interior; have very small vesicles and lysosomes.

a. Monocytes

b. Lymphocytes

Leukocytes

• Most WBCs are not in the circulatory system, but in tissues or organs of the lymphatic system.

• Circulate for only a short time in vessels.

Characteristics of WBCs• Move along the capillaries by amoeboid

movement.

• Detect chemicals from injured cells.

• Leave the capillary by squeezing through cells –diapedesis.

• Are positively chemotactic in the tissue.

• Can destroy things by phagocytosis.

Ameboid Movement and Phagocytosis

White Blood Cell Diapedesis

Infected Cell

Neutrophils• Most abundant of WBCs.• Granules are neutral. Filled with

toxins.• Have a dense, segmented nucleus of

2 to 5 lobes- Polymorphonuclear (PMNs).

• Very mobile and arrive at site of infection first.

Neutrophils• Phagocytize “tagged” bacteria.

• Breakdown bacteria with their toxic granules.

• Also, release chemicals to call WBCs to the site- interleukins.

Neutrophils

Eosinophiles• Granules stain with eosin- a red dye.• Only amount 2-4 % of the WBCs.• Have a bilobed nucleus.• Phagocytize bacteria and cell debris.• Use exocytosis to release toxins onto the surface

of large parasites.• Release chemicals that cause allergic reactions.

Eosinophil

Neutrophil and Eosinophil

Basophiles• Stain very darkly. Very small cells.• Very rare in circulation. Usually in tissue.• Release granules of histamine and heparin. • Histamine = permeability of capillaries.• Heparin = blood clotting.• Do not phagocytize.

Basophil

The Last Type of PhilHow’s that

blood working for you?

Monocytes• Larger cells with oval nuclei.

• Circulate throughout the blood stream.

• Leave the vessel and become macrophages.

• Macrophages phagocytize bacteria, cell debris, and other foreign elements.

• Also, release chemical messengers.

Monocyte

Lymphocytes• Larger than RBCs and lack deeply-

stained granules. Single, large nucleus.

• Abundant in blood. Migrate from blood to tissue through lymph return to blood.

• Most are not found in blood at any one time.

Lymphocyte

3 Kinds of Lymphocytes• T Cells: cellular immunity against foreign tissue

and cells infected with viruses; have killer T cells and helper T cells (CD-4 and CD-8).

• B cells: humoral immunity, produce antibodies (globulin proteins).Also memory cells.

• NK cells: (Natural Killers) large granules of toxin that destroy cancerous cells and some virally-infected cells.

Leukemia

Platelets• Called thrombocytes in

nonmammals.

• Circulate for 9-12 days.

• Platelets are only cell fragments in mammals.

Platelet Function

• Transport of proteins and enzymes important to the clotting process.

Platelet Function

• Active contraction after clot formation has occurred.

• Contain actin & myosin.

• After clot forms contraction shrinks clot & reduces size of break in vessel wall

Platelet Function

• Formation of a temporary patch in the walls of damaged blood vessels.

–Forms a platelet plug: slows the rate of blood loss while clotting continues.

Blood Clot

Platelet Production

• Thrombocytopoiesis occurs in the bone marrow.

• Bone marrow contains: Megakaryocytes: enormous w/ large nuclei.

Platelet Production• Megakaryocytes make proteins,

enzymes, & membranes.

• Shed cytoplasm in small membrane-enclosed packets: Platelets that enter circulation.

• Mature megakaryocyte produces 4000 platelets.

Megakaryocyte

What happens when we have an allergic reaction?

Can allergies kill?

An Application

Video: Discovery-Body Story- Allergies