Agenda

 Fetal Circulation  http://www.indiana.edu/~anat550/cvanim/fetcirc/fetcirc.html

 http://www.youtube.com/watch?v=OV8wtPYGE-I  Blood Components  http://www.youtube.com/watch?NR=1&v=CRh_dAzXuoU  http://www.youtube.com/watch?v=Rpj0emEGShQ&feature=rel ated

Think About it…

 As a fetus who was dependant on your mother, what aspects of your circulatory, respiratory and waste management systems would be different?

 What is unnecessary?

 What areas might cause complications?

Unique Structures:

The fetal circulatory system can’t be the same as the adult, if you stop to think about it. The fetus, first of all, can’t breathe air inside the womb, so sending blood to the lungs won’t do much good. Likewise, the fetus must get all its nutrients from Mom, as well as let her take care of its wastes. Obviously, some serious plumbing problems must be solved.

To solve these problems, the fetus has four features not present in adults.

 1.

OVAL OPENING

(foramen ovale): opening between the two atria, covered by a flap that acts like a valve. Some of the blood from the right atrium is therefore pumped through this flap and into the left atrium, bypassing the pulmonary circuit.  If the oval opening doesn’t close after birth, it can cause mixing of blood and “blue babies”. This is very inefficient because deoxygenated blood gets mixed with oxygenated blood. Correct with open heart surgery.

 2.

ARTERIAL DUCT

: (ductus arteriosus) connects pulmonary artery and aorta. Much of the blood being pumped out of the heart to the lungs will be directed away from the lungs and into the aorta. Like the oval opening, the arterial duct’s function is to bypass the pulmonary circuit.

 3.

UMBILICAL ARTERIES AND VEINS

travel to and from PLACENTA (a membrane shared by the mother and baby across which gases, nutrients, and wastes are exchanged). The umbilical arteries are grafted to the iliac arteries.

: vessels that  4.

VENOUS DUCT

(ductus venosus): connects umbilical vein to the venae cava to bring the blood back to the baby’s heart. It attaches right at the babies liver, but bypasses most of the liver. This is why chemicals ingested by the mother can seriously affect the baby!

The Placenta

PATH OF BLOOD THROUGH FETUS

 1. Begin with blood collecting in Right Atrium  2. From there, blood can go into Left Atrium through Oval opening plus into Right Ventricle through atrioventricle valve.

 3. Right Ventricle to Pulmonary Artery. Most of blood will go through arterial duct into aorta.

 4. Aorta to tissue. Umbilical arteries lead to placenta, where exchange of gases and nutrients take place.

 5. Umbilical vein carries O 2 -rich blood. It enters the venous duct, passes through liver.

 6. Venous duct joins with inferior venae cava (it mixes here with deoxygenated blood) and this mixed blood goes back to the back to heart.

Blood

 Blood is a form of liquid body tissue.  Blood has many functions within the body.    It transports oxygen and nutrients to the tissue fluid surrounding cells and carries away carbon dioxide and other cellular waste products. Blood also helps balance fluid levels, temperature, ion concentrations, and pH within the body. Formed elements in blood (cells) also play important roles in fighting disease and forming clots following tissue damage.

Blood is composed of two main parts.

 The liquid component of blood, called plasma, is mainly water (92%) with many dissolved substances.  Plasma makes up 55% of the volume of blood.  The remaining 45% of the blood volume is composed of

formed elements or blood cells

of various kinds. These cells are

red blood cells, white blood cells, and platelets

(actually cell fragments).

Plasma



Mainly water which acts as a solvent for the other substances found dissolved in plasma.



The dissolved substances include;



Plasma proteins - Albumin (maintains blood volume), Immunoglobulins (fight infection), and fibrinogen (blood clotting).

    

Salts - sodium ion, potassium ion, chloride ion, calcium ion, etc.

Nutrients - glucose, amino acids, fatty acids, some vitamins.

Gases - oxygen from lungs and carbon dioxide from the tissues.

Waste - urea from the liver.

Hormones - many - examples are thyroxine, insulin, adrenalin, estrogen, etc.

Blood Cells (Formed Elements)

• • • All of the following blood cell types are produced in the red bone marrow. Red bone marrow is located in the ribs, vertebrae, skull, and the ends of long bones in the arms and legs.

a.

RED BLOOD CELLS

(ERYTHROCYTES) Transport oxygen, formed in bone marrow. Over 95% of formed elements are erythrocytes.

b.

WHITE BLOOD CELLS

(LEUKOCYTES) Fight infection, formed in bone marrow and lymphoid tissue.

c.

PLATELETS

blood clotting (THROMBOCYTES) Function in

 The majority of the cells found in blood are red blood cells or erythrocytes. RBC's are shaped like biconcave disks and have no nuclei.  This flattened shape increases the surface area for gas exchange and aids their transport in capillaries. A single milliliter of blood will normally contain 4 to 6 billion RBC's. RBC's are functional in the blood for up to 4 months.  New RBC's are continually being produced in the red bone

Function

 The function of RBC's is to carry oxygen from the lungs and deliver it to the body tissues in the capillaries.  RBC's contain proteins called hemoglobin. Each hemoglobin molecule is composed of four polypeptide chains (an example of quaternary protein structure). Each of the four polypeptides has a heme group containing iron. It is this heme group that binds to oxygen and releases it to the tissues of the body in the capillaries.

White blood cells

 are larger cells that contain nuclei and vary in colour. WBC's are spherical in shape.  Theses WBC's function in the body to fight infection and develop immunity to future infections. There are many different kinds of WBC's each with a specific function with the body. The size and appearance of these WBC's varies greatly and allows them to be recognized using a microscope. The life span of a specific type of WBC's also varies from several days to years depending on the type of cell and its location. Like RBC's all of the WBC's are produced in the red bone marrow from stem cells that differentiate into the many different types of blood cells.

CommonWBC



Neutrophils

- Most common WBC, phagocytic (they engulf and ingest foreign substances or invaders like bacteria (pathogens) and destroy them.



Lymphocytes

- Mature in lymphatic tissues such as the thymus and spleen. There are two main types - B lymphocytes and T lymphocytes - both produce antibodies and provide secondary immunity. 

Antibodies

are protein molecules that travel in blood and lymph (tissue fluid) and attach to specific foreign antigens with a lock and key mechanism similar to enzymes.  Antibodies act in many ways to prevent disease. Antibodies are produced to recognize a specific

antigen

(foreign substance that is recognized by the immune system as non-self and needs to be destroyed). Antibodies deal with foreign antigens by attaching to them and promoting phagocytosis by other WBC's, or clumping pathogens together, or forming complexes with pathogens that prevents them from attaching to cells in the respiratory tract and digestive tract causing disease.

Continued



Monocytes

- largest WBC's, develop into large macrophages in the body tissues that phagocytize pathogens during infection.



Eosinophils

- are involved in control of allergic and inflammatory responses.



Basophils

- release histamine that increases blood flow to sites of tissue injury.

Platelets (thrombocytes)

Platelets are cell fragments that break away from larger cells in the red bone marrow. A milliliter of blood contains up to 300 million platelets. Platelets are involved in blood clotting following tissue injury. Blood clotting is a complex process involving platelets, many clotting factors, the proteins fibrinogen and prothrombin, vitamin K found in green vegetables and produced by bacteria in the large intestine, and calcium ions. In the clotting process following injury, platelets act as a first line of defense by forming a platelet plug that acts to seal up the leak.

Later, a complex series of events form a protein net around the platelet plug which traps RBC's. As tissue repair takes place the plug is dissolved and blood flow resumes.

ANTIBODIES

: VERY SPECIFIC PROTEINS that attach to invading pathogens

      Lymphocytes produce antibodies in response to invading pathogens.

Each lymphocyte produces one type of antibody that is specific for one type of antigen. An antigen is a foreign substance (usually a protein, sometimes a carbohydrate) that stimulates the release of antibodies to it. e.g. an antigen could be protein coat of a virus.

Antibodies combine with antigens in such a way that the killer T cells can destroy them. Each antibody fits its antigen like a lock and key.

An individual is immune to an antigen if he/she has antibodies to that particular antigens.

The blood in the individual contains lymphocytes that can remain in the system for years, ready to produce antibodies if that antigen is detected.

Exposure to the antigen, either naturally or by way of a vaccine, can cause active immunity to develop.

BLOOD TYPES

 What do you already know about blood types  How does blood transfusions and blood matching work?

BLOOD TYPING

     Human blood is classified according to the antigens present on the surface of the red blood cells. The most common blood types belong to the ABO Grouping.

Two antigens that may be present on the red cells are called "A" and "B". An individual may have one of these antigens present (in which case they will have type A or type B blood), or both (type AB) or neither (type O). Therefore, there are four blood types in the ABO Grouping.

Each individual also carries antibodies in his/her plasma to the antigens not present on that individual's red cells. e.g. Type A blood has antibody b, Type AB blood has no antibodies.

If the same antigen and antibody are present, agglutination (or clumping) of red cells will occur (can cause death).

Blood recipients may only receive donated blood for which they have no antibodies in their plasma.

Blood Transfusions

 Blood that has antibodies on it that is not recognized by the body will be attacked by your immune system 
  O is the Universal Donor because a person with this type of blood does not have antigens on the surface of the blood cells - hence will not cause an immune reaction in the patient.


  AB is the universal Acceptor because this person will not have an immune reaction to A, B, AB, or O*Just remember, the antigens on the surface of your cells (or donated cells) will cause a reaction if your immune system does not recognize them as being part of you. Hence, if you are Type A, and transfused with Type B, your body will mobilize a massive immune response against the "invading" blood. This will cause coagulation of blood and death.