Movement and Circulatory System Test

Movement-Circulatory-System-TEST

The Human Circulatory System

The Human Circulatory System
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The Transport System

Substances must be moved to where they are to be used or stored. The move­ment of materials within a cell or between parts of an organism is called circulation. The term transport refers to circulation and all other processes by which substances pass into or out of cells and move within the organism.

In simple organisms, the processes of diffusion, active trans­port, and cytoplasmic streaming are adequate for circulating materials within cells and between cells. However, in large or complex organisms, many cells are far from the external envi­ronment. Such organisms need a special circulatory system to move materials to all parts of the organism. The circulatory system links the cells of the organism to its environment.

A circulatory system has three components;

(1)    A fluid in which transported materials are dissolved;  Blood

(2)    A network of tubes or body spaces through which the fluid flows; Blood vessels

(3)    A means of driving the fluid through the tubes or spaces. Heart

In animals, the circulatory fluid is usually called blood. The network of tubes is the blood vessels. The organ that pumps blood through the system is called the heart

.

Functions of circulatory system

    1-To transport oxygen to the cells: the circula­tory system is delivering oxygen to the cells. Oxygen combines with food inside of body cells to produce usable energy. Without energy, body cells would soon die. The cells that use the most oxygen—and the first to die without oxygen — are brain cells.

   2- To remove carbon dioxide: When cells combine oxygen and food to produce energy, they also produce a waste product called carbon dioxide. Removing carbon dioxide is another important job of the circulatory system.

   3-To transport food and waste products:  transport food to all body cells. At the same time, wastes produced by the cells are carried away by the blood. If the blood did not remove such wastes, the body would poison itself with its own waste products!

   4-To defense the body against microorganisms: Sometimes the body comes under attack from microscopic organisms such as bacteria and viruses. At these times, another transporting function of the circulatory system comes into play—body defense. The blood rushes disease-fighting cells and chemi­cals to the area under attack.

    5-To transport the chemical messengers: The circulatory system transports other chemicals as well. These chemicals carry messages sent from one part of the body to another. For example: a chemical messenger from the pancreas is carried by the blood to the liver. Its message is "Too much sugar in the blood; remove some of the sugar and store it."

The Human Circulatory System

Humans, like other vertebrates, have a closed circulatory system. The system includes the fluid that contains requiring materials, it is blood. A single heart which pumps the blood, and a network of blood vessels, which carries the blood to and from all the cells of the body. There are three kinds of blood vessels—arteries, veins, and capillaries.

Blood Vessels

  Arteries:

   The blood vessels that carry blood away from the heart to the organs and tissues of the body are the arteries. The walls of arteries are thick and elastic. They contain layers of connective tissue, muscle tissue, and epithe­lial tissue. As an artery enters a tissue or organ, it divides and subdivides many times to form smaller and smaller arteries. The smallest arteries are called arterioles.

  

Veins:

      The blood vessels that return blood from the body tissues to the heart are the veins. The smallest veins are called venules. The venules join together to form veins, which also merge, forming larger and larger veins. The walls of veins are thin and only slightly elastic. Inside the veins are flap like valves that allow the blood to flow in only one direction—toward the heart. When the valves do not function properly, blood tends to accumulate within the vein. The walls of the vein become stretched and lose their elasticity. This condition is called varicose veins.

Capillaries:

       Arterioles and venules are connected by net­works of microscopic capillaries. The walls of the capillaries consist of a single layer of epithelial cells. These vessels are so narrow that red blood cells pass through them in single file. Dissolved nutrients, wastes, oxygen, and other substances are exchanged between the blood and the body cells while blood flows through the capillaries.

 The Heart

The heart is a pump whose rhythmic contractions force the blood through the vessels. This muscular organ is larger than your fist and is located slightly to the left of the middle of the chest cavity, under the breastbone and between the lungs. It is composed mostly of cardiac muscle.

Structure of heart

     The outside of the heart is surrounded by protective membrane, the pericardium. The space between its two surface is filled with fluid that is facilitates heart function and protects it from external hazards

     The middle layer of heart is called myocardium, composed of cardiac muscle. Only this layer contains blood vessels or cardiac vessels. It is thin in the atria but thicker in the ventricles. The cells of the heart muscle do not obtain their nutrients from the blood with in the heart directly. The cardiac vessels in the myocardiac layer supply nutrient to the heart cells. Another way, nutrients of heart are provided by myocardium. The function of this layer are; the pumping by contraction of cardiac muscle and to supply nutrients for heart .

    The inner layer of heart is called endocardium. It is composed of a single layer of epithelial cells. This layer connected to myocardium by connective tissue. This layer contain no blood vessels but in a gelatinous structure. The function of this layer is to prevent the erosion of the heart during contraction and relaxation.

Parts of heart

      The heart has two sides, right and left. These two halves are separated by a wall called the septum. Each half has two chambers. There is a thin-walled chamber called the atrium, and there is a thick, muscular ventricle. The two atria are reservoirs for the blood that enters the heart. They contract at the same time. This contraction forces blood into the two ventricles. Next, the muscular walls of the ventricles contract forcing the blood through the arteries.

      The flow of blood through the heart is controlled by four flap-like valves that allow the blood to flow in only one direc­tion. Two of these valves, called the atrioventricular, or A-V, valves, allow blood to flow from the atria into the ventricles. They prevent the flow of blood from the ventricles into the atria. In the right side of the heart, the A-V valve is called the tricuspid valve because it has three flaps. In the left side, it is called the bicuspid, or mitral valve. The other two valves, called the semilunar valves, allow blood to move from the ventricles into the pulmonary artery and the aorta. They prevent backflow from these arteries into the ventricles.

      Actually, the heart is a double pump. The right side of the heart sends oxygen-poor blood to the lungs, while the left side sends oxygen-rich blood to the rest of the body.

 Circulation through the Heart

The blood first enters the right atrium of the heart from two different directions. Blood enters through the superior vena cava and the inferior vena cava. The superior vena cava carries blood from the head and upper parts of the body. The inferior vena cava returns blood from the lower parts. From the right atrium, blood goes through the right a-v valve into the right ventricle. Then the right ventricle con­tracts. This forces blood through a set of s-l valves into the pulmonary arteries. These arteries carry the blood to the lungs. The blood passes through the lung and into the right and left pulmonary veins. These vessels return blood to the heart and open into the left atrium. From there, the blood passes through the left a-v valve into the left ventricle; finally, blood passes out the aorta and goes to all parts of the body.

The heart muscle cells are nourished by special arteries called coronary arteries. The right and left coronary arteries branch off from aorta . They curve down­ward around each side of the heart. Each sends off smaller vessels that penetrate the heart muscle.  

The heartbeat cycle:

     The pumping action of the heart in­volves two main periods. During one of these periods, the heart muscle is relaxed. This period of relaxation is called diastole. During the other period, the heart muscle is contracting. The period of contraction is called systole.

 Have you ever listened to your heart in a stethoscope?

     The heart of an average adult beats about 70 times per minute. This is when the person is resting. During hard work or exercise, the heart rate may be as high as 180 beats per minute.

Control of the heartbeat

The cardiac muscle is different from the other muscle tissues of the body. Cardiac muscle fibers form a network.

       The contraction of other types of muscle is controlled by the nervous system. Cardiac muscle has ability to contract. Even when it is removed from the body, the heart will keep beating for a while if kept in a spe­cial solution. Each heart-muscle fiber has its own innate rate of contraction. This is made possible by a structure in the heart called the sinoatrial node, also called the pacemaker. This pacemaker is a specialized group of muscle cells in the wall of the right atrium. Contraction of the heart is initiated by electrical impulses from the pacemaker. A specialized system of fibers carries the impulses to all parts of the heart, causing the atria to contract first, and then the ventricles.

      The minute electrical current produced each time the heart contracts can be recorded on a machine that produces an electrocardiogram, or EKG. Physicians use electrocardiograms to check the health of the heart.

      The rate of the heartbeat is regulated by certain nerves that enter the pacemaker. Impulses from the vagus nerves slow down the pacemaker, while impulses from the cardioaccelerator nerves speed up the pacemaker. The built-in rhythm of the heart is also affected by changes in body temperature and by certain chemi­cals circulating in the blood.

      When the natural pacemaker of the heart does not function properly, the wires from a battery-powered electronic pacemaker can be attached surgically to the heart to regulate the heartbeat

THE BLOOD:COMPOSITION OF BLOOD

Functions and Components of Blood

   Blood is the liquid tissue of transport in humans and other vertebrates. Because it is a liquid, blood can transport dis­solved and suspended materials. It carries respiratory gases, nutrients, cellular wastes, and regulatory substances, such as enzymes and hormones.

   Blood contributes to the regulation of all bodily functions. It maintains and regulates the chemical state, pH, and water content of cells and body fluids. Blood is also involved in the regulation of body temperature.

 Blood protects the body. The white blood cells and certain substances found in the blood protect the body from disease-causing microorganisms. The ability of the blood to clot pro­tects the circulatory system from collapse that could be caused by loss of fluid from a wound.

      The average human body contains about 5.5 liters of blood. Blood is a unique tissue in that it is made up of blood cells and a liquid called plasma.  55 percent of the total volume of the blood is plasma, while the blood cells, red blood cells, white blood cells, and platelets, make up about 45 percent.

PLASMA

     The major portion of the blood is a yellow-colored liquid called plasma. It consists mainly of water (over 90 percent) and dissolved pro­teins (7 percent). It also contains salts, glucose, amino acids, fatty acids, vitamins, hormones, and cellular wastes.

      The three types of protein found in blood plasma are albumin, globulins, and fibrinogen.

     Albumin, which is the most abundant of the plasma proteins, causes an osmotic gradient that regulates the diffusion of plasma out of the capillaries into the intercellular spaces.

      The globulins serve a number of different functions. Some globulins are involved in the transport of proteins and other substances from one part of the body to another. Other globulins, particularly the gamma globulins, play a major role in the body's defense against infection.

      Fibrinogen is impor­tant in the clotting of blood.

BLOOD CELLS

There are three types of blood cells. Red blood cells, white blood cells, and platelets.

Red blood cells:

    Red blood cells, or erythrocytes, are the most numerous of the cells in the blood (about 5 mil­lion per cubic millimeter of blood). Their major function is to transport oxygen from the lungs to the body tissues and carbon dioxide from the body tissues to the lungs.

      Red blood cells are disk-shaped cells that are thinner in the center than around the rim. However, they easily change shape. They are filled with the iron-containing pigment hemoglobin, which gives blood its characteristic red color. Hemoglobin functions in the transport of oxygen and carbon dioxide.

      During the development of the human embryo, red blood cells are produced by various organs, including the liver, spleen, and lymph nodes. After birth, however, they are nor­mally produced only by the bone marrow. Mature red blood cells contain no nucleus. They live for about 120 days. Worn-out red cells are removed from the circulation by the liver and spleen and broken down. The iron from the hemoglobin molecule is reused by the body.

       Anemia is a condition in which a person has too few red blood cells or insufficient hemoglobin. In anemia, the cells of the body do not receive an adequate sup­ply of oxygen. Some forms of anemia can be treated by injec­tions of vitamin B₁₂ or by eating iron-rich foods.

White Blood Cells

       The white blood cells, or leucocytes, protect the body against infection by bacteria and other microorganisms.

      White blood cells are larger than red blood cells, and unlike red cells, they contain one or more nuclei.

      Leukocytes are produced by the bone marrow and by lympha­tic tissues. The mature leukocytes enter the bloodstream. They can squeeze between the cells of capillary walls and move through the body tissues. When there is an infection at a particular site in the body, the leukocytes collect there.

      Structurally, there are several different kinds of white blood cells. However, in terms of function, leukocytes fall into two groups. One type acts as phagocytes, engulfing microorganisms and other matter. The sec­ond type is involved in the production of antibodies, which are protein molecules that attack foreign sub­stances or microorganisms that enter the body.

       Normally, there are only 6,000 to 8,000 white blood cells per cubic millimeter of blood. However, when there is an infec­tion in the body, the number may increase to 30,000 per cubic millimeter. Among the phagocytic leukocytes, most can ingest from 5 to 25 bacteria before they die. The pus that forms at the site of an infected wound consists mainly of white blood cells that have died after ingesting bacteria.

       Leukemia is a form of blood cancer in which there is an uncontrolled increase in the number of white blood cells. Some forms of leukemia can now be con­trolled or even cured by drugs.

Platelets

     Platelets are small, round or oval fragments of a type of blood cell formed in the bone marrow. A platelet, which has no nucleus or color, consists of a bit of cytoplasm sur­rounded by a cell membrane. There are gen­erally from 200,000 to 400,000 platelets per cubic millimeter of blood. Platelets start the blood clotting process to repair injured blood vessels.

BLOOD CLOTTING: The Clotting Process

    When a blood vessel is broken, the escape of blood is stopped by the formation of a solid mass that plugs up the hole, a blood clot. The solidification of blood is called clotting. Clotting is carried out primarily by the platelets and the plasma protein fibrinogen. The overall process of blood clot­ting may be summarized as follows;

1. Clotting is started by the release of a substance called thromboplastin from the wall of the in­jured blood vessel..

2. As soon as the vessel is injured, platelets begin to stick to the broken vessel wall and to release thromboplastin as well.

3. The presence of thromboplastin and of several other factors at the site of the injury causes a complex series of enzyme-controlled reactions convert the plasma protein prothrombin to thrombin. Vitamin K is needed for producing of prothrombin.

4. Thrombin, which is an enzyme, converts another plasma protein, fibrinogen, into insoluble strands of fibrin. Thrombin also makes platelets sticky so that the hole in the vessel wall becomes filled with a mass of platelets and fibrin strands.

5. Red blood cells become trapped in the mass of fibrin strands and platelets and fill in the wound. As water evapo­rates from the clot, it hardens into a scab.

6. The wound is repaired by the growth of cells called fibroblasts and by an outer layer of epithelial cells.

     Clotting must be prevented if blood is to be used for trans­fusions. Calcium ions are necessary for many of the clotting reactions and are present in plasma. If sodium citrate is added to blood, calcium ions bind to the citrate and clotting cannot occur. Citrated blood is used for most blood transfusions

 Disorders of the Blood

Anemia    :  Body produces too few red blood cells

Leukemia: Body produces too many white blood cells; many do not work properly

Hemophilia: Blood does not clot properly

Sickle Cell Disease: Red blood cells have abnormal sickle shape, causing them to clog small blood vessels

       Any substance that can cause an immune response is called an antigen. Most antigens are proteins, but carbohydrates and nucleic acids may also be antigens. Most microorganisms and most toxins (poisonous substances produced by bacteria) contain substances that are antigens. Each human body contains a unique combination of proteins that no other human has. As a result, tissue from one person transplanted into another will contain "foreign" proteins that act as antigens. The presence of antigens in the body brings about an immune response that acts to destroy the antigens or the foreign tissue carrying them.

Lymphocytes and antibodies

        The recognition and destruc­tion of foreign antigens in the body tissues is carried out by the Lymphocytes. Lymphocytes are produced originally in the bone marrow of developing embryos. They enter the bloodstream, pass into the body tissues, and finally collect in the lymphoid tissues. There are two types of lymphocytes  —

              B-lymphocytes and

             T-lymphocytes.

Before becoming established in the lymphoid tissue, both B and T lymphocytes undergo "processing" at special sites in the lymphatic system. Without this processing, they cannot recog­nize antigens. It is estimated that there are between 10,000 and 100,000 different kinds of antigen receptors on human lympho­cytes. However, each individual lymphocyte has receptors for only one kind of antigen. When an antigen enters the body, only those lymphocytes with receptors that recognize that particular antigen become activated. Depending on the anti­gen, B Iymphocytes, T Iymphocytes, or both may be stimulated.

When B Iymphocytes are activated by antigens, they en­large and undergo repeated cell divisions, forming two differ­ent types of cells—plasma cells and memory cells. Plasma cells secrete antibodies, which are proteins that react specifi­cally with antigens and inactivate them. Antibodies have active sites that fit a particular site on a par ticular antigen. There are several different classes of anti­bodies, and they inactivate antigens in different ways (see Table).

The memory cells produced by the activated B-lymphocytes remain in the lymphoid tissue. If the same antigen enters the body again, the memory cells immediately begin to produce antibodies against it, thereby providing immunity to that disease.

      When a T lymphocyte is stimulated by an antigen, it also undergoes rapid cell division, forming more lymphocytes sensitive to that antigen. Some of these newly formed T lymphocytes remain in the lymphoid tissue and serve as memory cells. The rest pass from the lymphoid tissue into the circulatory system and body tissues. When they come in contact with the antigens to which they are sensitive, they combine with them and destroy them.The Human Circulatory System

ANIMAL TISSUE STRUCTURE

Animal Tissue Structure
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ANIMAL TISSUE STRUCTURE

                   All vertebrates share the same basic body plan, with similar tissue and organ that operate in much the same way. The micrograph show a portion of the duodenum, part of digestive system, which is made up of multiple types of tissue. Group of cells that are similar in structure and function are organized into tissue. Early in development, the cells of the growing embryo differentiate into three fundamental embryonic tissue, called  germ layers. From the innermost to the outermost layers, these are the endoderm, mesoderm and ectoderm. Each germ layer, in turn, differentiates into the scores of different cell types and tissues that are characteristic of the vertebrate body.

            In adult vertebrates, there are four principal kinds of tissues, or primary tissues: They are epithelial, connective, muscle and nerve tissue, and each type. 

Four fundamental characteristics of epithelial tissue.

          (1)  densely packed cells joined by a variety of specialized intercellular junctions
          (2)  form linings (sheets and layers) which exhibit polarity, i.e., epithelia have apical and basal surfaces
          (3)  the basal surface is attached to, and supported by, underlying connective tissue
          (4)  avascular (no direct blood supply)

  Eight types of epithelium, distinguished by cell shape and pattern of layering.

          (1)  simple squamous
          (2)  simple cuboidal 
          (3)  simple columnar 
          (4)  pseudostratified 
          (5)  stratified squamous 
          (6)  stratified cuboidal 
          (7)  stratified columnar 
          (8)  transitional 

 The three arrangements of epithelial tissue by number of cell layers using correct scientific terminology.

          (1)  simple - one cell layer thick
          (2)  pseudostratified - more than one cell layer thick
          (3)  stratified - appears in the microscope as if multiple layers were present, but actually only one cell layer present, cells of different height

  The four shapes of epithelial cells using correct scientific terminology.

          (1)  squamous - flat
          (2)  cuboidal - about as wide as tall 
          (3)  columnar - tall narrow cells 
          (4)  transitional - cells that change shape depending on whether the tissue is relaxed or stretched

Explain or describe: 

Classify the various epithelial tissues by shape and layers. Describe at least one function and location in the body for each type of epithelium

Epithelial Tissue Type	Example of a Location and Function
simple squamous	alveolar lining - gas exchange; parietal wall of nephron capsule - lining; visceral wall of glomerulus - plasma filtration to make urine
simple cuboidal	ducts of salivary glands, pancreatic acinar glands - delivery of exocrine secretion; proximal and distal convoluted tubules in kidneys - urine formation
simple columnar	stomach and intestinal linings - digestion and absorption of nutrients
pseudostratified	trachea & bronchi - mucous traps dust and microbes
stratified squamous	skin, oral and nasal cavities, vagina, distal urethra - protective linings
stratified cuboidal	ureters and proximal urethra - protective linings
stratified columnar	pharynx, male urethra, some glandular ducts (minor component in each case) - transitional zone within protective linings
transitional	urinary bladder - extensible protective lining

3. the location and structure of endothelium and mesothelium.

	Location	Structure
Endothelium	interior lining of heart chambers and blood vessels	simple squamous epithelium
Mesothelium	interior lining of sterile body cavities; serous membranes of pericardial, pleural and abdominal cavities; lining of chambers housing and circulating cerebrospinal fluid (CSF)	simple squamous epithelium

4. the difference between endocrine versus exocrine glands.

Endocrine Glands	Exocrine Glands
Their secretions are carried away from the glands by the blood stream.	Their secretions are carried away from the glands in ducts.
Their secretions are delivered to internal target tissues and organs.	Their secretions are delivered to body surfaces, either mucous membranes or the skin.
Their secretions are internal regulatory substances.	Their secretions have a variety of functions, but they are not internal regulatory substances.