Chapter 15: Endocrine System

This chapter provides an overview of the endocrine system. The endocrine system is more like a satellite radio or television signals broadcast widely so that every radio or television set, with its receiver adjusted properly, can receive the signals. It sends information to the cells it controls in the form of chemical signals, called hormones, which are released form the endocrine glands.


Functions of the Endocrine System:
1. Metabolism and tissue maturation
2. Ion regulation
3. Water balance
4. Immune system regulation
5. Heart rate and blood pressure regulation
6. Control of blood glucose and other nutrients
7. Control of reproductive functions
8. Uterine contractions and milk release


First of all you must be familiar with the different glands of the endocrine system

Classes of Receptors

The two major categories of hormone receptors are membrane-bound receptors and intracellular receptors.


Membrane-bound receptors are receptors that extend across the plasma membrane and have their receptor sites exposed to the outer surface of the plasma membrane.


To understand more about this, watch this video below:

Intracellular receptors are receptors in the cytoplasm or in the nucleus of the cell. Hormones that diffuse through the plasma membrane bind to intracellular receptors and the hormone-receptor complex then initiates the cell's response.


Here is a video on how it works:

Before we move on to the next topic, let us first refresh our minds of the different glands in the endocrine system. Here is a link below that will lead you to a review-activity:

http://www.wisc-online.com/Objects/ViewObject.aspx?ID=MEA1104

Pituitary Gland and Hypothalamus

The hypothalamus of the brain regulates the secretory activity of the pituitary gland. Hormones, sensory information that enters the central nervous system, and emotions, in turn, influence the activity of the hypothalamus.

The pituitary gland is divided functionally into two parts: the posterior and anterior pituitary.

The posterior pituitary, or neurohypophysis is formed during embryonic development form an outgrowth of the inferior part of the brain in the area of the hypothalamus.

The posterior pituitary stores and secretes two polypeptide hormones called antidiuretic hormone and oxytocin.

Antidiuretic hormone (ADH) is so named because it prevents the output of large amounts of urine. It is sometimes called Vasopressin. 

Oxytocin binds to membrane-bound receptors and causes contraction of smooth muscle cells of the uterus and milk ejection, or milk "let-down", from the breasts in lactating women. It also plays an important role in the expulsion of the fetus from the uterus during delivery.

For more information about ADH, watch this video below:

For more information about Oxytocin, watch this video below:

Anterior pituitary hormones include growth hormone, thyroid-stimulating hormone, adrenocorticotropic hormone and related substances, luteinizing hormone, follicle-stimulating hormone, and prolactin. 

To have more information about the hormones in the anterior pituitary, watch the video below:

Thyroid Gland

The thyroid gland is composed of small, hollow balls of cells called follicles, which contain thyroglobulin.

Thyroid Hormones are triiodothyronine (T3) and tetraiodothyronine (T4). Another name for T4 is thyroxine.

Here is a video about the physiology of thyroid hormones for you to understand more about it:

Calcitonin
1. An increase in blood calcium levels stimulates calcitonin secretion.
2. Calcitonin decreases blood Ca2+ levels by inhibiting osteoclasts.

Here is a rap or song about calcitonin on how it works on our body:

Parathyroid Glands
1. The parathyroid glands are embedded in the thyroid gland.
2. Parathyroid hormone (PTH) increases blood Ca2+ levels.
3. A decreases in blood calcium levels stimulates PTH secretion

Below is a video on how parathyroid hormone works:

Adrenal Glands
1. The adrenal glands are near the superior poles of the kidneys.
2. The adrenal medulla arises from the same cells that give rise to postganglionic sympathetic neurons.
3. The adrenal cortex is divided into 3 layers: zona glomerulosa, zona fasciculata and the zona reticularis.

Hormones of the Adrenal Medulla
1. Epinephrine accounts for 80% and norepinephrine for 20% of the adrenal medulla hormones.

Hormones of Adrenal Cortex
1. Aldosterone acts on the kidneys to increase Na+ and to decrease K+ and H+ levels in the blood.
2. Cortisol increases fat and protein breakdown, increases glucose synthesis from amino acids, decreases the inflammatory response, and is necessary for the development of some tissues.
3. In females, androgens stimulate axillary and pubic hair growth and sexual drive.

Here is a video on how body works with adrenal glands:

To enhance more our skills, try this link; it is a game show about the different glands. Enjoy and learn at the same time! :)

http://www.wisc-online.com/Objects/ViewObject.aspx?ID=NUR3103

Pancreas

1. The exocrine portion of the pancreas consists of a complex duct system, which ends in small sacs, called acini, that produce pancreatic digestive juices.

2. The endocrine portion consists of the pancreatic islets. Each islets is composed of alpha cell, which secrete glucagon, and beta cells, which secrete insulin.

Within the islets, alpha cells secrete glucagon and beta cells secrete insulin.

Insulin

Insulin is a hormone produced by the pancreas which is central to regulating carbohydrate and fat metabolism in the body. Insulin causes cells in the liver, muscle, and fat tissue to take up glucose from the blood, storing it as glycogen in the liver and muscle.

To understand more on how insulin is produced, you can watch this video below:

Glucagon

Glucagon, a hormone secreted by the pancreas, raises blood glucose levels. Its effect is opposite that of insulin, which lowers blood glucose levels. The pancreas releases glucagon when blood sugar (glucose) levels fall too low. Glucagon causes the liver to convert stored glycogen intoglucose, which is released into the bloodstream.

To understand more about glucagon production, watch the video below:

Testes and Ovaries

Testes is one of two male reproductive glands located in the scrotum; produces spernatozoa, testosterone and inhibin.

Ovaries is one of two female reproductive glands  located in the pelvic cavity; produces the secondary oocyte, estrogen and progesterone.

Pineal Body

It produces melatonin.

Click the link below for quizzes to enhance your knowledge about the endocrine system

http://www.wisc-online.com/Objects/ViewObject.aspx?ID=AP15004

http://www.wisc-online.com/Objects/ViewObject.aspx?ID=NUR3203

End of Chapter 15

Chapter 16: Blood

The average adult has about 4-5 liters in female and 5-6 liters in male of blood living inside of their body, coursing through their vessels, delivering essential elements, and removing harmful wastes. Without blood, the human body would stop working.

Blood is the fluid of life, transporting oxygen from the lungs to body tissue and carbon dioxide from body tissue to the lungs. Blood is the fluid of growth, transporting nourishment from digestion and hormones from glands throughout the body. Blood is the fluid of health, transporting disease fighting substances to the tissue and waste to the kidneys.

Blood is a type of connective tissue, consisting of cells and cell fragments surrounded by a liquid matrix. The cells and cell fragments are the formed elements, and the liquid is the plasma. The formed elements make up about 45%, and plasma makes up about 55% of the total blood volume. Blood makes up about 8% of the total weight of the body.

Plasma is a pale yellow colored, clear liquid that is 91% water; 7% proteins; and 2% other substances, such as ions, nutrients, gases, and waste products. It is also an essential ingredient for human survival.

It might seem like plasma is less important than the blood cells it carries. But that would be like saying that the stream is less important than the fish that swims in it. You can't have one without the other.

Besides water, plasma also contains dissolved salts and minerals like calcium, sodium, magnesium, and potassium. Microbe-fighting antibodies travel to the battlefields of disease by hitching a ride in the plasma.

Without plasma, the life-giving blood cells would be left floundering without transportation. Never underestimate the importance of plasma.

Plasma proteins are proteins found in the blood plasma, the clear, protein-rich fluid which is left behind when platelets, red blood cells, and white blood cells are removed from the blood. These proteins play a number of important roles in the human body, and levels of plasma proteins are sometimes evaluated in a laboratory analysis to gather information about a patient's general health and specific health issues which a patient may be experiencing. Plasma proteins make up around 7% of the total blood volume, with levels which can fluctuate at times.

Plasma proteins include albumin, globulins, and fibrinogen.

·         Albumin acts as a transporter and a regulator of osmotic pressure

·         Globulins are involved in transport and immune processes

·         Fibrinogen is primarily involved in blood clotting

Activation of clotting factors results in the conversion of fibrinogen into:

o   Fibrin is a threadlike protein that forms blood clots

    Serum is plasma without the clotting factors

About 95% of the volume of the formed elements consist of red blood cells (RBCs), or erythrocytes; white blood cells (WBCs), or leukocytes; and platelets, or thrombocytes.

The process of blood cell production is called hematopoiesis.

When a blood vessel is severely damaged, blood clotting, or coagulation, results in the formation of a blood clot. A blood clot is a network of threadlike protein fibers, called fibrin, that traps blood cells, platelets, and fluid.

The formation of a blood clot depends on a number of proteins, called clotting factors. Most clotting factors are manufactured in the liver, and many of them require vitamin K for their synthesis. In addition, many of the chemical reactions of clot formation require Ca2+ and the chemicals released from platelets. Low levels of vitamin K, low levels of Ca2+, low numbers of platelets, or reduced synthesis of clotting factors because liver dysfunction can seriously impair the blood-clotting process.

1.    The extrinsic pathway of clotting starts with thromboplastin, which is released outside of the plasma in damaged tissue.

2.    The intrinsic pathway of clotting starts when inactive factor XII, which is in the plasma, is activated by coming into contact with a damaged blood vessel.

3.    Activation of the extrinsic or intrinsic clotting pathway results in the production of activated factor X.

4.    Activated factor X, factor V, phospholipids, and Ca2+ from prothrombinase.

5.    Prothrombin is converted to thrombin by prothrombinase.

6.    Fibrinogen is converted to fibrin by thrombin.

7.    Thrombin activates clotting factors, promoting clot formation and stabilizing the fabrin clot.

My blood type is O, what’s yours? If you don’t know, well, here’s how.

Purchase a blood type testing kit. If you or someone you know happens to work in a medical setting, see if you can get your hands on one of these tests for free.

·         Dispense one drop of your blood to each field on the test card. Use a sterilized needle. The fields contain antibodies, which will provoke a reaction with antigens on your red blood cells.

·         Use a new toothpick for each field to mix the blood with the impregnation, creating an about dime-sized smear.

o   If you have blood type A, clumping will appear in following fields: anti-A

o   If you have blood type B, clumping will appear in the field: anti-B

o   If you have blood type AB, clumping will appear in fields anti-A, anti-B

o   If you have blood type O, no clumping will appear.

Landsteiner observed two distinct chemical molecules present on the surface of the red blood cells. He labeled one molecule "A" and the other molecule "B." If the red blood cell had only "A" molecules on it, that blood was called type A. If the red blood cell had only "B" molecules on it, that blood was called type B. If the red blood cell had a mixture of both molecules, that blood was called type AB. If the red blood cell had neither molecule, that blood was called type O.

If two different blood types are mixed together, the blood cells may begin to clump together in the blood vessels, causing a potentially fatal situation. Therefore, it is important that blood types be matched before blood transfusions take place. In an emergency, type O blood can be given because it is most likely to be accepted by all blood types. However, there is still a risk involved.

A person with type A blood can donate blood to a person with type A or type AB. A person with type B blood can donate blood to a person with type B or type AB. A person with type AB blood can donate blood to a person with type AB only. A person with type O blood can donate to anyone.

A person with type A blood can receive blood from a person with type A or type O. A person with type B blood can receive blood from a person with type B or type O. A person with type AB blood can receive blood from anyone. A person with type O blood can receive blood from a person with type O.

Because of these patterns, a person with type O blood is said to be a universal donor. A person with type AB blood is said to be a universal receiver. In general, however, it is still best to mix blood of matching types and Rh factors.

To understand better ABO Blood Group, here’s a video that would help you:

Scientists sometimes study Rhesus monkeys to learn more about the human anatomy because there are certain similarities between the two species. While studying Rhesus monkeys, a certain blood protein was discovered. This protein is also present in the blood of some people. Other people, however, do not have the protein. The presence of the protein, or lack of it, is referred to as the Rh (for Rhesus) factor.

If your blood does contain the protein, your blood is said to be Rh positive (Rh+). If your blood does not contain the protein, your blood is said to be Rh negative (Rh-).

This Rh factor is connected to your blood type. For example, your blood may be AB+ which means that you have type AB blood with a positive Rh factor. Or, you might have O- blood which means that you have type O blood with a negative Rh factor.

It is particularly important for expectant mothers to know their blood's Rh factor. Occasionally, a baby will inherit an Rh positive blood type from its father while the mother has an Rh negative blood type. The baby's life could be in great danger if the mother's Rh negative blood attacks the baby's Rh positive blood. If this happens, an exchange transfusion may save the baby's life. The baby's blood can be exchanged for new blood that matches the mother's.

End of Chapter 16

Chapter 17: Heart

Functions:

1. Generating blood pressure

2. Routing blood

3. Regulating blood supply

Pericardium - a sack surrounding the heart and consisting of the fibrous pericardium and serous pericardium

Heart Wall has 3 layers:

1. Epicardium

2. Myocardium

3. Endocardium

Anatomy of the heart

Here is video explaining the circulation of the blood through the heart:

Here are some activities for you to understand and for the knowledge to be retain in your minds:

http://www.wisc-online.com/Objects/ViewObject.aspx?ID=AP12504

http://www.wisc-online.com/Objects/ViewObject.aspx?ID=NUR1403

http://www.wisc-online.com/Objects/ViewObject.aspx?ID=OTA1304

End of Chapter 17

Chapter 18: Blood Vessels and Circulation

     The previous chapter is all about the anatomy of the heart so before we go to this chapter let us recall of what you have learned to the previous topic. Click Here.

     The peripheral circulatory system consists of two sets of blood vessels: the systemic and pulmonary vessel.

• Systemic Circulation- supplies nourishment to all of the tissue located throughout your body, with the exception of the heart and lungs because they have their own systems. Systemic circulation is a major part of the overall circulatory system.
• Pulmonary Circulation- is the movement of blood from the heart, to the lungs, and back to the heart again. This is just one phase of the overall circulatory system.

 Aorta and Major Arteries of the Systemic Circulation

 

 Major Veins of the Systemic Circulation