By Cynthia Woods,2014-08-02 18:25
25 views 0

    INSTRUCTOR: DATE: CLASS PERIOD: COURSE: AgSc 332 Animal Science UNIT: Explanation of Animal Anatomy and Physiology Related to Nutrition,________

     Reproduction, Health, and Management of Domesticated Animals LESSON: The Circulatory System TEKS: 119.62 (c)(2)(A) IMS REFERENCE: IMS # 8646-A SUGGESTED HOURS OF INSTRUCTION: 1 ? hours


The student will be able to:

    ; illustrate the anatomy and physiology of the heart;

    ; recognize the anatomy and physiology of the vascular system;

    ; identify the anatomy and physiology of systems within the circulatory system; and

    ; describe the anatomy and physiology of the total circulatory system.


    agglutinate alveoli antibodies antigens apex biconcave bicuspid bronchial cardiac

    caudal coagulation colostrums

    cranial cytoplasm dehydration

    dilate endocrine endothelial

    gastric glucose hepatic

    histamine impermeable inorganic

    lumbar mesenteric metabolism

    oxygenated parasites placental

    Porcine Stress Syndrome renal systemic Thoracic tricuspid tuberculosis


    ; IMS Lesson #8646-A

    ; PowerPointfor Lesson #8646-A: The Circulatory System ?

    ; Class Notes for Lesson #8646-A: The Circulatory System

    ; Test for Lesson #8646-A


Preparation (Interest Approach/Motivator)

    Key Points Methods Link/Motivation:



    Key Points Methods

    INTRODUCTION Teacher-led

     discussion using The circulatory system is comprised of the heart, veins, capillaries, PowerPoint #8645-A.

    arteries, lymph vessels, and lymph glands, which work together to

     supply the body tissues with nourishment and collect waste material.

     Functions of the circulatory system:

    ; Distribute nutrients,

     ; Transport and exchange oxygen and carbon dioxide,

    ; Remove waste materials,

     ; Distribute secretions of endocrine glands,

    ; Prevent excessive bleeding,

     ; Prevent infection, and

    ; Regulate body temperature.


    The heart: ; is a funnel-shaped hollow, muscular organ.

    ; is located near center of the thoracic cavity. ; broad end, or base, supported by large arteries and veins.

    ; pointed end, or apex, is directed toward the abdomen.

    The heart wall is made up of three layers: ; Epicardium - outer layer of heart wall, which is also the inner

    layer of the epicardial sac; ; Endocardium - inner layer that consists of endothelial cells,

    which line the heart, cover the heart valves, and line the blood vessels; and

    ; Myocardium - middle layer composed of cardiac muscle. The cardiac muscle is an involuntary, striated muscle with fibers

    that intertwine.

    Mammalian heart: ; divided into left and right sides.

    ; each side has atrium and ventricle. ; Therefore, the heart is said to have four chambers (right

    atrium, right ventricle, left atrium, and left ventricle).

    Refer to illustration of heart in note sheets.

    ; Atrioventricular valves (AV valve) - separate the atrium and ventricle on each side of the heart; prevent backflow of blood;

    tricuspid valve on right side, bicuspid valve on left side.

    ; pulmonary valve and the aortic valve prevent backflow of blood into their respective ventricles. The pulmonary valve is located

    between the right ventricle and the pulmonary artery. The aortic valve is located between the left ventricle and the aortic


    ; sinoatrial node (SA node) control the beat of the heart by

    sending out electrical signals to make the heart pump.

    Application #2 If possible, obtain heart specimens fro swine, cattle, and chickens for comparison.


     The vascular system is made up of three types of blood vessels:

    ; arteries,

     ; capillaries, and

    ; veins.

     Arteries - carry oxygen-rich blood from the heart to other parts of the body; have thick walls of elastic-like tissue; branch out into smaller

     arteries called arterioles.

     Arterioles - composed of large amounts of smooth muscle instead of the elastic tissue; branch into smaller vessels called capillaries. At this junction, the arterioles have an especially thick layer of smooth muscle in their walls that carefully controls the amount of blood each capillary receives.

    Blood pressure maintained by the tension at the end of the arterioles. Shock is a serious condition that occurs when the arterioles dilate (relax) and allow a large volume of blood into the capillary beds. The reduced blood flow that occurs with shock jeopardizes vital organs.

    Capillaries - tiny, thin-walled blood vessels that connect arteries to veins; so small in diameter that blood cells pass through in a single file; semi-permeable membrane allows for diffusion of nutrients and wastes.

    Veins - are the blood vessels that return blood to the heart from all parts of the body; capillaries unite to form small veins called venules. The venules join together to form larger veins, which have thin walls and are collapsible. For each artery, there is a much larger vein

    counterpart. Veins have valves that aid the return flow of blood and prevent the blood from reversing flow.


    The total circulatory system is divided into two main parts: pulmonary circulation and systemic circulation.

Pulmonary Circulation

    Pulmonary circulation is the part of the circulatory system that takes the blood from the heart to the lungs, where it is oxygenated, and returns it to the heart. The main parts of the pulmonary circulation system include the heart, pulmonary arteries, capillaries of the lungs, and pulmonary veins.

Flow of Blood in Pulmonary Circulation

    Blood low in oxygen returns to heart through superior (or cranial) vena cava and the inferior (or caudal) vena cava;

    ? enters the right atrium;

? passes through the right atrioventricular (tricuspid) valve into the

     right ventricle;

    ? through the pulmonary valve into the pulmonary artery, which

     quickly divides into two branches;

    ? to the lungs, where pulmonary arteries branch into capillaries that

     surround the alveoli. Carbon dioxide diffuses out of blood, oxygen

     fuses into blood.

    ? oxygenated blood returns to the heart through pulmonary vein into

     the left atrium;

    ? flows through the left atrioventricular (bicuspid) valve into the left


    The thick-walled left ventricle pumps the blood through the aortic valve into the aorta. The amount of pressure that is required for pulmonary circulation is much less than what is required for systemic

    circulation. Therefore, the muscle mass developed in the right ventricle is much less than that of the left ventricle.

    Un-oxygenated blood is dark or brownish red, while oxygenated blood is bright red. In the pulmonary system, un-oxygenated blood is

    carried by the pulmonary arteries and oxygenated blood is carried by pulmonary veins. In the systemic system, arteries carry oxygenated blood and veins carry un-oxygenated blood.

The Systemic Circulation System

The systemic circulation includes the flow of oxygenated blood

    from the heart to the tissues in all parts of the body and the return of un-oxygenated blood back to the heart. The blood vessels, including the arteries, capillaries, and veins, are the main parts of systemic circulation.

    Through systemic circulation, oxygen and nutrients are delivered to the body tissues via the arteries. Blood is filtered during systemic circulation by the kidneys (most of the waste) and liver (sugars). The systemic circulatory system is complex and its functions vary. The

    systemic circulatory system is divided into subsystems for particular regions of the body.

Flow of Blood Through the Systemic Circulatory System

Oxygenated blood leaves the left ventricle of the heart through the

    aorta, the largest artery in the body.

    The left and right coronary arteries immediately branch from the aorta

    and carry fresh blood to the heart muscle itself. The coronary veins

    quickly return that blood back to the heart. A heart attack often involves a clot in the coronary arteries or their branches.

    The brachiocephalic trunk is the next branch from the aorta. The carotid arteries branch off the brachiocephalic trunk and carry oxygenated blood to the neck and head region. Blood from the neck and head region is returned by the jugular veins. The left and right brachial arteries also branch from the brachiocephalic trunk to supply blood to the shoulders and forelegs.

    The thoracic aorta refers to the portion of the aorta that goes from the heart, through the thoracic cavity to the diaphragm. The portion of the aorta that goes from the diaphragm, through the abdominal region, to the last lumbar vertebrae is called the abdominal aorta.

    Branches from the thoracic aorta supply oxygenated blood to the lungs (via bronchial arteries), esophagus, ribs, and diaphragm. The celiac artery branches from the aorta immediately past the diaphragm and itself branches into the gastric, splenic, and hepatic arteries. The gastric artery supplies blood to the stomach. The splenic artery

    supplies blood to the spleen. The hepatic artery supplies blood to the liver.

    The cranial and caudal mesenteric arteries branch from the abdominal aorta and carry blood to the small and large intestines. The renal arteries are next to branch from the abdominal aorta.

The renal arteries have two important functions:

    ; Supply blood to the kidneys, and

    ; Carry large volumes of blood to the kidneys for filtration and


    From the renal arteries arise arteries that supply blood to the testicles

    in males (internal spermatic arteries) and parts of the reproductive system in females (uteroovarian arteries).

    The abdominal aorta ends where it branches into the internal and external iliac arteries. The internal iliac artery supplies blood to the

    pelvic and hip region. The external iliac artery branches into the femoral arteries. The femoral arteries and their branches supply oxygenated blood to the hind legs.

    Veins normally accompany arteries and often have similar names. Veins are always larger than the arteries and are sometimes more visible than arteries because they are closer to the skin surface. Most veins eventually empty the un-oxygenated blood into the vena cavas.

The cranial veins return the blood from the head, neck, forelegs, and

    part of the thoracic cavity to the right atrium of the heart via the superior vena cava. These cranial veins include the jugular vein, brachial veins, internal thoracic veins, and the vertebral veins.

The caudal veins return blood from the iliac, lumbar, renal, and

    adrenal veins to the right atrium of the heart via the inferior vena cava.

    Before blood is returned to the heart from the stomach, pancreas, small intestine, and spleen, it goes through the liver for filtration. This portion of the systemic system is known as the hepatic portal system. The gastric vein (stomach), splenic vein (spleen), pancreatic vein (pancreas), and mesenteric veins (small intestines) empty into the portal vein that carries the blood to the liver. In the liver, the portal

    vein branches into smaller venules and finally into capillary beds. In the capillary beds of the liver, nutrients are exchanged for storage and the blood is purified. The capillaries then join into venules that empty into the hepatic vein, which carries blood to the inferior (caudal) vena cava.


    The lymphatic system is part of the immune system and acts as a secondary (accessory) circulatory system.

Functions of the lymphatic system:

    ; Remove excess fluids from body tissues,

    ; Absorb fatty acid and transport fat to circulatory system, and

    ; Produce immune cells (lymphocytes, monocytes, and

    plasma cells).

Blood fluid escapes through the thin-walled capillaries into spaces

    between body tissue cells. Lymph vessels, which have very thin

    walls, pick up thee fluids called lymph. The lymph vessels join to form larger ducts that pass through lymph nodes (or glands). Each lymph node has a fibrous outer covering (capsule), a cortex, and a medulla.

    Lymph nodes filter foreign substances, such as bacteria and cancer cells, from the lymph before it is re-entered into the blood system

    through the larger veins. Lymph nodes, which are scattered among the lymph vessels, act as the body’s first defense against infection.

Lymph nodes produce the following cells:

    ; Lymphocytes - a type of white blood cell,

    ; Monocytes - a leukocyte that protects against blood-borne

    pathogens, and

    ; Plasma cells - produce antibodies.

Each lymph node has its own blood supply and venous drainage. The

    lymph nodes usually have names that are related to their location in the body. When a specific location gets infected, the lymph nodes in that area will enlarge to fight the infection. If the lymph node closest to an infected area is unable to eliminate the infection, other lymph

    nodes in the system will attempt to fight the infection. This is particularly critical in the case of cancer, which can be spread from its point of origin to all parts of the body through the lymphatic system.


    Blood is an important component of the circulatory system. Anatomically and functionally, blood is a connective tissue. The amount of blood that a domestic animal has is expressed in terms of percentage of body weight (cattle - 7.7%; sheep - 8.0%; and horses -


Components of Blood

    Plasma, which makes up 50 - 65% of the total volume of blood, is a straw-colored liquid containing water (90%) and solids (10%). The solids in plasma include inorganic salts and organic substances, such

    as antibodies, hormones, vitamins, enzymes, proteins, and glucose (blood sugar). The non-plasma, or cellular, portion of blood is

    composed of red blood cells, white blood cells, and platelets.

Red blood cells, called erythrocytes, are responsible for carrying

    oxygen from the lungs to various body tissues. Red blood cells contain hemoglobin, which gives them their characteristic red color and helps

    them carry the oxygen. Red blood cells are biconcave discs, a shape that provides a large area for oxygen exchange. Red blood cells are produced in the red marrow of bones. Most domestic animals have a red blood cell count of seven million cells per cubic milliliter of blood. Red blood cells will last from 90 to 120 days and are removed from the

    blood by the spleen, liver, bone marrow, or lymph nodes when they are worn out.

    Anemia is a condition caused by low levels of red blood cells and hemoglobin. Anemia can be caused by :

    ; Loss of blood due to injury,

    ; Infestations of blood-sucking parasites, or

    ; Low levels of red cell production due to poor nutrition.

    Hemoconcentration is a condition in which there is an above normal level of red blood cells. Hemoconcentration is normally caused by dehydration (loss of body fluid), which can be the result of vomiting,

    diarrhea, or any chronic disease characterized by high body temperatures.

Blood platelets, or thrombocytes, are oval-shaped discs that are

    formed in the bone marrow. Blood platelets help prevent blood loss from injuries to blood vessels by forming clots (white thrombus).

    Platelets may secrete a substance that causes the clot to contract and solidify. Platelets may also secrete a substance that causes an injured vessel to constrict at the injury.

White blood cells, or leukocytes, are divided into two general

    categories: granulocytes and agranulocytes.

    Granulocytes are the category of leukocytes that contain granules within the cytoplasm.

    Granulocytes include:

    ; Neutrophils - produced by bone marrow; neutrophils fight

    disease by migrating to the point of infection, absorbing

    bacteria, and destroying them. Neutrophils dissolve dead

    tissue resulting in a semi-liquid material called pus. An

    abscess is a concentrated area of pus.

    ; Eosinophils - a type of granulocyte that plays a role in

    combating infection by parasites, as well as, impacting

    allergies and asthma. They contain most of the histamine

    protein in the blood, which is an indication of allergic reaction

    when elevated.

    ; Basophils - rare granulocytes that are responsible for the

    symptoms of allergies, including inflammation.

    Agranulocytes are the category of leukocytes that contain very little, if any, granules. Agranulocytes are produced by the lymph nodes, spleen, thymus, and other lymphoid tissue.

    There are two types of agranulocytes:

    ; Lymphocytes - agranulocytes that produce and release

    antibodies at the site of infections to fight disease.

    Lymphocytes also produce antibodies that allow an animal to

    build up immunities to a particular disease.

    ; Monocytes - agranulocytes that absorb disease-producing

    materials, such as bacteria that cause tuberculosis, through

    phagocytosis. Unlike neutrophils, monocytes do not produce

    pus. Monocytes join body tissue to form larger,

    disease-absorbing masses called macrophages.

    In domestic animals, approximately 85% to 90% of the leukocytes in domestic mammals are neutrophils and lymphocytes. The total number of neutrophils and lymphocytes are about equal, but temporary stress increases the ratio of neutrophils to lymphocytes until that stress is removed.

    When bacterial infections occur, the number of white blood cells normally increases. When viral infections occur, the number of white

    blood cells normally decreases. Therefore, the concentration of white blood cells can help diagnose disease.

    Blood clotting is called coagulation and is important in reducing blood loss caused by injury and in healing the injury. Fibrin is a thread-like

    mass produced by fibrinogen (fibrous protein in blood) and thrombin. Fibrin holds the red blood cells, white blood cells, and platelets

    together to form a blood clot. Coagulation times for livestock species vary: cattle- 6 ? minutes; swine - 3 ? minutes; sheep 2 ? minutes;

    and horses - 11 ? minutes. Vitamin K helps maintain

    Antithromboplastin and antithrombin, which are two substances that

    prevent blood from clotting within the circulatory system.

    Blood types are classified based on certain antigens and antibodies found on the surface of red blood cells. Young animals can receive certain antibodies from their mothers. These antibodies must be

    passed on to the young animal through the colostrums milk because the placental membrane is fairly impermeable. When two different blood types, an antigen and its antibody, combine as a result of mating, the reaction would cause agglutination or clumping together of red blood cells. This may cause some deaths during the early embryonic development in animals.

    Many blood types and groups have been identified in domestic animals.

    ; Cattle have 9 recognized blood groups;

    ; Horses have 8 recognized blood groups; and

    ; Canine have 13 described groups, but only 8 recognized groups.

    Some blood types can cause disease in the offspring of animals. Individual animals and their parents can be identified using blood-typing. Bulls used for commercial artificial insemination must be blood-typed. Certain blood types may be connected to superior production and/or performance in animals. For example, egg production and hatchability can be improved in chickens and Pork Stress Syndrome (PSS) can be identified in swine.


    Key Points Methods

Application #1:

Complete note sheets. Note sheet

Application #2:

Compare heart specimens from swine, cattle, and chickens. Laboratory

    Identify chambers of the heart and note differences in thickness of heart walls.


    Key Points Methods

Evaluation #1:

    Complete selected student activities from #8645-A. Worksheet

Evaluation #2:

     Complete lesson test for #8645-A. Worksheet


    Campbell, J. R. and Lasley, J. F. The Science of Animals that Serve Humanity. St. Louis, MO: McGraw Hill Book Company, 2001.

    Circle of Blood. [Online]. Available: [2001, September].

    Frandson, R. D. Anatomy and Physiology of Animals. Philadelphia, PA: Lea & Fibiger, 1992.

Glossary of Terms. [Online]. Available:


    Stufflebeam, Charles E. Principles of Animal Agriculture, Englewood Cliffs, NJ: Prentice Hall, Inc. 1983.

Report this document

For any questions or suggestions please email