Regulation of Hunger

Factor that affecting food intake:

Leptin
•       Since the discovery of leptin and its receptors , there has been a rapid accumulation of information about genes, peptides, other neurotransmitters, and receptors in the hypothalamus and neighboring areas that are involved in appetite regulation.
•       leptin operates as part of a feedback loop by which the size of the body's fat depots can operate through a humoral link to regulate food intake
•       One important factor is neuropeptide Y
•       When injected into the hypothalamus, this 36-amino-acid polypeptide increases food intake, and inhibitors of neuropeptide Y synthesis decrease ood intake.
•       Neuropeptide Y-containing neurons have their cell bodies in the arcuate nuclei and project to
•       the paraventricular nuclei.
•       Neuropeptide Y mRNA in the hypothalamus increases during feeding and decreases during satiety.
•       Neuropeptide Y exerts its effect through three known receptors—Y1, Y2, and Y5—all coupled to G proteins.
•       Activation of the Y5 receptor increases food intake, but the situation is complex because activation of the Y2 receptor has an apparent inhibitory effect.
•       Knockout of the neuropeptide Y gene does not produce marked effects on feeding, indicating that other pathways are also involved, but knocking out the neuropeptide Y gene in leptin-deficient ob/ob mice causes them to eat less and expend more energy than ob/ob controls that have intact neuropeptide Y genes.


Orexin-A and orexin-B
•       Other polypeptides that increase food intake include orexin-A and orexin-B, derived from the same gene by alternate splicing.
•       They act on two receptors.
•       Orexins are synthesized in neurons located in the lateral hypothalamus.
•       They are also of interest because a mutation in one of the orexin receptor genes causes narcolepsy in dogs.


Melanin-concentrating hormone
•       Another polypeptide that increases food intake in mammals is melanin-concentrating hormone,
•        19-amino-acid polypeptide which is secreted by the pituitary in fish and is involved in the control of their skin color .
•       In mammals, its mRNA is found only in the lateral hypothalamus and the zona incerta


Pro-opiomelanocortin (POMC) derivatives
•       On the other hand, pro-opiomelanocortin (POMC) derivatives  decrease food intake.
•       There are four established receptors for these derivatives:
•       MC1-R, which is involved in skin pigmentation;
•       MC2-R, which is involved in adrenal glucocorticoid production;
•       MC3-R, which is associated with the control of sebaceous gland secretion; and
•       MC4-R, which mediates the effects on appetite.


CART (cocaine- and amphetamine-regulated transcript)
•       Another neuropeptide found in the hypothalamus that inhibits food intake is CART (cocaine- and amphetamine-regulated transcript).


CRH
•       CRH, the brain hormone that stimulates ACTH secretion also inhibits food intake


Catecholamines
•       Catecholamines are also involved in the regulation of body weight.
•       Mice in which norepinephrine and epinephrine synthesis is prevented by knocking out the gene for dopamine b-hydroxylase have increased food intake.
•       Interestingly, they do not become obese because they also have an unexplained simultaneous increase in metabolic rate.
•       Amphetamine and related drugs used clinically to suppress appetite presumably act by releasing norepinephrine in the CNS.
•       Mice in which the 5HT2C receptor is knocked out become obese, indicating that serotonin is also involved in the regulation of food intake.

Gastric bypass surgery

Gastric bypass is surgery that helps you lose weight by changing how your stomach and small intestine handle the food you eat.
After the surgery, your stomach will be smaller. You will feel full with less food.
The food you eat will no longer go into some parts of your stomach and small intestine that absorb food. Because of this, your body will not get all of the calories from the food you eat.


Description
You will have general anesthesia before this surgery. You will be asleep and pain free.
There are two steps during gastric bypass surgery:

• The first step makes your stomach smaller. Your surgeon uses staples to divide your stomach into a small upper section and a larger bottom section. The top section of your stomach (called the pouch) is where the food you eat will go. The pouch is about the size of a walnut. It holds only about 1 ounce (oz) of food. Because of this you will eat less and lose weight.
• The second step is the bypass. Your surgeon connects a small part of your small intestine (the jejunum) to a small hole in your pouch. The food you eat will now travel from the pouch into this new opening and into your small intestine. As a result, your body will absorb fewer calories.
Gastric bypass can be done in two ways. With open surgery, your surgeon makes a large surgical cut to open your belly. The bypass is done by working on your stomach, small intestine, and other organs.
Another way to do this surgery is to use a tiny camera, called a laparoscope. This camera is placed in your belly. The surgery is called laparoscopy. The scope allows the surgeon to see inside your belly.
In this surgery:

• The surgeon makes 4 to 6 small cuts in your belly.
• The scope and instruments needed to perform the surgery are inserted through these cuts.
• The camera is connected to a video monitor in the operating room. This allows the surgeon to view inside your belly while doing the operation.
Advantages of laparoscopy over open surgery include:

• Shorter hospital stay and quicker recovery.
• Less pain.
• Smaller scars and a lower risk of getting a hernia or infection.
This surgery takes about 2 to 4 hours.
Why the Procedure is Performed
Weight-loss surgery may be an option if you are very obese and have not been able to lose weight through diet and exercise.
Doctors often use the body massa index (BMI) and health conditions such as type 2 diabetes and high blood pressure to determine which patients are most likely to benefit from weight-loss surgery.
Gastric bypass surgery is not a quick fix for obesity. It will greatly change your lifestyle. After this surgery, you must eat healthy foods, control portion sizes of what you eat, and exercise. If you do not follow these measures, you may have complications from the surgery and poor weight loss.
This procedure may be recommended if you have:

• A BMI of 40 or more. Someone with a BMI of 40 or more is at least 100 pounds over their recommended weight. A normal BMI is between 18.5 to 25.
• A BMI of 35 or more and a serious medical condition that might improve with weight loss. Some of these conditions are obstructive sleep apnea, type 2 diabetes, and heart disease
Risks
Gastric bypass is major surgery and it has many risks. Some of these risks are very serious. You should discuss these risks with your surgeon.
Risks for anesthesia and surgery in general include:

• Allergic reactions to medicines
• Breathing problems
• Bleeding, blood clots, infection
Risks for gastric bypass include:

• Gastritis (inflamed stomach lining), heartburn, or stomach ulcers
• Injury to the stomach, intestines, or other organs during surgery
• Leaking from the line where parts of the stomach have been stapled together
• Poor nutrition
• Scarring inside your belly that could lead to a blockage in your bowel in the future
• Vomiting from eating more than your stomach pouch can hold
Before the Procedure
Your surgeon will ask you to have tests and visits with other health care providers before you have this surgery. Some of these are:

• A complete physical exam.
• Blood tests, ultrasound of your gallbladder, and other tests to make sure you are healthy enough to have surgery.
• Visits with your doctor to make sure other medical problems you may have, such as diabetes, high blood pressure, and heart or lung problems, are under control.
• Nutritional counseling.
• Classes to help you learn what happens during the surgery, what you should expect afterward, and what risks or problems may occur afterward.
• You may want to visit with a counselor to make sure you are emotionally ready for this surgery. You must be able to make major changes in your lifestyle after surgery.
If you smoke, you should stop several weeks before surgery and not start smoking again after surgery. Smoking slows recovery and increases the risks of problems. Tell your doctor or nurse if you need help quitting
Tell your surgeon or nurse:

• If you are or might be pregnant
• What medicines, vitamins, herbs, and other supplements you are taking, even ones you bought without a prescription
During the week before your surgery:

• You may be asked to stop taking medicines that make it hard for your blood to clot. These include aspirin, ibuprofen (Advil, Motrin), vitamin E, warfarin (Coumadin), and others.
• Ask your doctor which drugs you should still take on the day of your surgery.
• Prepare your home for after the surgery.
On the day of surgery:

• Follow instructions about when to stop eating and drinking.
• Take the drugs your doctor told you to take with a small sip of water.
• Arrive at the hospital on time.
After the Procedure
Most people stay in the hospital for 1 to 4 days after surgery.
In the hospital:

• You will be asked to sit on the side of the bed and walk a little on the same day you have surgery.
• You may have a (tube) catheter that goes through your nose into your stomach for 1 or 2 days. This tube helps drain fluids from your intestine.
• You may have a catheter in your bladder to remove urine.
• You will not be able to eat for the first 1 to 3 days. After that, you can have liquids and then pureed or soft foods.
• You may have a tube connected to the larger part of your stomach that was bypassed. The catheter will come out of your side and will drain fluids.
• You will wear special stockings on your legs to help prevent blood clots from forming.
• You will receive shots of medicine to prevent blood clots.
• You will receive pain medicine. You will take pills for pain or receive pain medicine through an IV, a catheter that goes into your vein.
You will be able to go home when:

• You can eat liquid or pureed food without vomiting.
• You can move around without a lot of pain.
• You do not need pain medicine through an IV or given by shot.
Be sure to follow instructions for how to care for yourself at home
Outlook (Prognosis)
Most people lose about 10 to 20 pounds a month in the first year after surgery. Weight loss will decrease over time. By sticking to your diet and exercise from the beginning, you lose more weight.
You may lose half or more of your extra weight in the first 2 years. You will lose weight quickly after surgery if you are still on a liquid or pureed diet.
Losing enough weight after surgery can improve many medical conditions, including:

• Asthma
• Gastroesophageal reflux disease
• High Blood Pressure
• High Cholesterol
• Obstructive sleep apnea
• Type 2 diabetes
• High cholesterol
• Obstructive sleep apnea
• Type 2 diabetes
Weighing less should also make it much easier for you to move around and do your everyday activities.
To lose weight and avoid complications from the procedure, you will need to follow the exercise and eating guidelines that your doctor and dietitian have given you.

Vital Sign

Vital signs are measurements of the body's most basic functions. The four main vital signs routinely monitored by medical professionals and health care providers include the following:

• Body temperature
• Pulse rate
• Respiration rate (rate of breathing)
• Blood pressure (Blood pressure is not considered a vital sign, but is often measured along with the vital signs.)
Vital signs are useful in detecting or monitoring medical problems. Vital signs can be measured in a medical setting, at home, at the site of a medical emergency, or elsewhere.


What is body temperature?
The normal body temperature of a person varies depending on gender, recent activity, food and fluid consumption, time of day, and, in women, the stage of the menstrual cycle. Normal body temperature can range from 97.8 degrees F (or Fahrenheit, equivalent to 36.5 degrees C, or Celsius) to 99 degrees F (37.2 degrees C) for a healthy adult. A person's body temperature can be taken in any of the following ways:

• Orally. Temperature can be taken by mouth using either the classic glass thermometer, or the more modern digital thermometers that use an electronic probe to measure body temperature.
• Rectally. Temperatures taken rectally (using a glass or digital thermometer) tend to be 0.5 to 0.7 degrees F higher than when taken by mouth.
• Axillary. Temperatures can be taken under the arm using a glass or digital thermometer. Temperatures taken by this route tend to be 0.3 to 0.4 degrees F lower than those temperatures taken by mouth.
• By ear. A special thermometer can quickly measure the temperature of the ear drum, which reflects the body's core temperature (the temperature of the internal organs).
• By skin. A special thermometer can quickly measure the temperature of the skin on the forehead.
Body temperature may be abnormal due to fever (high temperature) or hypothermia (low temperature). A fever is indicated when body temperature rises about one degree or more over the normal temperature of 98.6 degrees Fahrenheit, according to the American Academy of Family Physicians. Hypothermia is defined as a drop in body temperature below 95 degrees Fahrenheit.


What is the pulse rate?
The pulse rate is a measurement of the heart rate, or the number of times the heart beats per minute. As the heart pushes blood through the arteries, the arteries expand and contract with the flow of the blood. Taking a pulse not only measures the heart rate, but also can indicate the following:

• Heart rhythm
• Strength of the pulse
The normal pulse for healthy adults ranges from 60 to 100 beats per minute. The pulse rate may fluctuate and increase with exercise, illness, injury, and emotions. Females ages 12 and older, in general, tend to have faster heart rates than do males. Athletes, such as runners, who do a lot of cardiovascular conditioning, may have heart rates near 40 beats per minute and experience no problems.




How to check your pulse
As the heart forces blood through the arteries, you feel the beats by firmly pressing on the arteries, which are located close to the surface of the skin at certain points of the body. The pulse can be found on the side of the neck, on the inside of the elbow, or at the wrist. For most people, it is easiest to take the pulse at the wrist. If you use the lower neck, be sure not to press too hard, and never press on the pulses on both sides of the lower neck at the same time to prevent blocking blood flow to the brain. When taking your pulse:

• Using the first and second fingertips, press firmly but gently on the arteries until you feel a pulse.
• Begin counting the pulse when the clock's second hand is on the 12.
• Count your pulse for 60 seconds (or for 15 seconds and then multiply by four to calculate beats per minute).
• When counting, do not watch the clock continuously, but concentrate on the beats of the pulse.
• If unsure about your results, ask another person to count for you.
If your doctor has ordered you to check your own pulse and you are having difficulty finding it, consult your doctor or nurse for additional instruction.


What is the respiration rate?
The respiration rate is the number of breaths a person takes per minute. The rate is usually measured when a person is at rest and simply involves counting the number of breaths for one minute by counting how many times the chest rises. Respiration rates may increase with fever, illness, and with other medical conditions. When checking respiration, it is important to also note whether a person has any difficulty breathing.
Normal respiration rates for an adult person at rest range from 12 to 16 breaths per minute.


What is blood pressure?
Blood pressure, measured with a blood pressure cuff and stethoscope by a nurse or other health care provider, is the force of the blood pushing against the artery walls. Each time the heart beats, it pumps blood into the arteries, resulting in the highest blood pressure as the heart contracts. One cannot take his or her own blood pressure unless an electronic blood pressure monitoring device is used. Electronic blood pressure monitors may also measure the heart rate, or pulse.

Two numbers are recorded when measuring blood pressure. The higher number, or systolic pressure, refers to the pressure inside the artery when the heart contracts and pumps blood through the body. The lower number, or diastolic pressure, refers to the pressure inside the artery when the heart is at rest and is filling with blood. Both the systolic and diastolic pressures are recorded as "mm Hg" (millimeters of mercury). This recording represents how high the mercury column in an old-fashioned manual blood pressure device (called a mercury manometer) is raised by the pressure of the blood. Today, your doctor's office is more likely to use a simple dial for this measurement.

High blood pressure, or hypertension, directly increases the risk of coronary heart disease (heart attack) and stroke (brain attack). With high blood pressure, the arteries may have an increased resistance against the flow of blood, causing the heart to pump harder to circulate the blood.
According to the National Heart, Lung, and Blood Institute (NHLBI) of the National Institutes of Health, high blood pressure for adults is defined as:

• 140 mm Hg or greater systolic pressure

or
• 90 mm Hg or greater diastolic pressure
In an update of NHLBI guidelines for hypertension in 2003, a new blood pressure category was added called prehypertension:

• 120 mm Hg – 139 mm Hg systolic pressure

or
• 80 mm Hg – 89 mm Hg diastolic pressure
The NHLBI guidelines now define normal blood pressure as follows:

• Less than 120 mm Hg systolic pressure

and
• Less than 80 mm Hg diastolic pressure
These numbers should be used as a guide only. A single elevated blood pressure measurement is not necessarily an indication of a problem. Your doctor will want to see multiple blood pressure measurements over several days or weeks before making a diagnosis of hypertension (high blood pressure) and initiating treatment. A person who normally runs a lower-than-usual blood pressure may be considered hypertensive with lower blood pressure measurements than 140/90.


Why should I monitor my blood pressure at home?
For people with hypertension, home monitoring allows your doctor to monitor how much your blood pressure changes during the day, and from day to day. This may also help your doctor determine how effectively your blood pressure medication is working.


What special equipment is needed to measure blood pressure?
Either an aneroid monitor, which has a dial gauge and is read by looking at a pointer, or a digital monitor, in which the blood pressure reading flashes on a small screen, can be used to measure blood pressure.


Before you measure your blood pressure:
• Rest for three to five minutes without talking before taking a measurement.
• Sit in a comfortable chair, with your back supported and your legs and ankles uncrossed.
• Sit still and place your arm, raised level with your heart, on a table or hard surface.
• Wrap the cuff smoothly and snugly around the upper part of your arm. The cuff should be sized to fit smoothly, while still allowing enough room for one fingertip to slip under it.
• Be sure the bottom edge of the cuff is at least one inch above the crease in your elbow.
It is also important, when taking blood pressure readings, that you record the date and time of day you are taking the reading, as well as the systolic and diastolic measurements. This will be important information for your doctor to have. Ask your doctor or another health care professional to teach you how to use your blood pressure monitor correctly. Have the monitor routinely checked for accuracy by taking it with you to your doctor's office. It is also important to make sure the tubing is not twisted when you store it and keep it away from heat to prevent cracks and leaks.
Proper use of your blood pressure monitor will help you and your doctor in monitoring your blood pressure.

Heart Transplant


A heart transplant is surgery to remove a damaged or diseased heart and replace it with a healthy donor heart.

Finding a donor heart can be difficult. The heart must be donated by someone who is brain-dead but is still on life support. The donor heart must be matched as closely as possible to your tissue type to reduce the chance that your body will reject it.
You are put into a deep sleep with general anesthesia, and a cut is made through the breastbone.

• Your blood flows through a heart-lung bypass machine while the surgeon works on your heart. This machine does the work of your heart and lungs while they are stopped, and supplies your body with blood and oxygen.
• Your diseased heart is removed and the donor heart is stitched in place. The heart-lung machine is then disconnected. Blood flows through the transplanted heart, which takes over supplying your body with blood and oxygen.
• Tubes are inserted to drain air, fluid, and blood out of the chest for several days, and to allow the lungs to fully re-expand.


Why the Procedure is Performed
A heart transplant may be done to treat:

• Severe heart damage after a heart attack
• Severe heart failure, when medicines, other treatments, and surgery no longer help
• Severe heart defects that were present at birth and can't be fixed with surgery
• Life-threatening abnormal heartbeats or rhythms that do not respond to other treatments
Heart transplant surgery may not be used in people who:

• Are malnourished
• Are older than age 65 to 70
• Have had a severe stroke or dementia
• Have had cancer less than 2 years ago
• Have HIV infection
• Have infections, such as hepatitis, that are active
• Have insulin-dependent diabetes and other organs, such as the kidneys, that aren't working correctly
• Have kidney, lung, nerve, or liver disease
• Have no family support and do not follow their treatment
• Have other diseases that affect the blood vessels of the neck and leg
• Have pulmonary hypertension (thickening of blood vessels in the lung)
• Smoke or abuse alcohol or drugs, or have other lifestyle habits that may damage the new heart
• Are not reliable enough to take their medicines, or if the person is not able to keep up with the many hospital and medical office visits and tests

Risks
Risks from any anesthesia are:

• Reactions to medicines
• Problems breathing
Risks from any surgery are:

• Bleeding
• Infection
Risks of transplant include:

• Blood clots (deep venous thrombosis)
• Damage to the kidneys, liver, or other organs from anti-rejection medicines
• Development of cancer from the drugs used to prevent rejection
• Heart attack or stroke
• Heart rhythm problems
• High cholesterol levels, diabetes, and bone thinning from the use of rejection medicines
• Increased risk for infections due to anti-rejection medicines
• Lung and kidney failure
• Rejection of the heart
• Severe coronary artery disease
• Wound infections
Before the Procedure
Once you are referred to a transplant center, you will be evaluated by the transplant team. They will want to make sure that you are a good candidate for a transplant. You will visit many times over several weeks or even months. You will need to have blood drawn and x-rays taken. The following may also be done:

• Blood or skin tests to check for infections
• Tests of your kidney and liver
• Tests to evaluate your heart, such as EKG,echocardiogram, and cardiac catheterization
• Tests to look for cancer
• Tissue and blood typing, to help make sure your body will not reject the donated heart
• Ultrasound of your neck and legs
You will want to look at one or more transplant centers to see which would be best for you:

• Ask them how many transplants they perform every year and what their survival rates are. Compare these numbers with the numbers from other centers.
• Ask what support groups they have available and how much help they offer with travel and housing.
• Ask about the costs of medicines you will need to take afterwards.
If the transplant team believes you are a good candidate, you will be put on a regional waiting list for a heart:

• Your place on the list is based on several factors. Key factors include the type and severity of your heart disease, and how sick you are at the time you are listed.
• The amount of time you spend on a waiting list is usually NOT a factor for how soon you get a heart, except in the case of children.
Most, but not all, people who are waiting for a heart transplant are very ill and need to be in the hospital. Many will need some sort of device to help their heart pump enough blood to the body. Most often, this is a ventricular assist device (VAD).
After the Procedure
You should expect to stay in the hospital for 7 to 21 days after a heart transplant. The first 24 to 48 hours will likely be in the intensive care unit (ICU). During the first few days after a transplant, you will need close follow-up to make sure that you do not get an infection and your heart is working well.
The recovery period is about 3 months and often, your transplant team will ask you to stay fairly close to the hospital during that time period. You will need to have regular check-ups with blood tests, x-rays, and echocardiograms for many years.
Fighting rejection is an ongoing process. The body's immune system considers the transplanted organ a foreign body and fights it. For this reason, organ transplant patients must take drugs that suppress the body's immune response. To prevent rejection, it is very important to take these medicines and carefully follow your self-care instructions.
Biopsies of the heart muscle are often done every month during the first 6 to 12 months after transplant, and then less often after that. This helps determine if your body is rejecting the new heart, even before you have symptoms.
You must take drugs that prevent transplant rejection for the rest of your life. You will need to understand how to take these medicines, and know their side effects.
You can go back to your normal activities 3 months after the transplant as soon as you feel well enough, and after talking with your health care provider. However, avoid vigorous physical activity.
To make sure that you do not develop coronary disease after a transplant, you may have cardiac catheterization every year.
Outlook (Prognosis)
Heart transplant prolongs the life of people who would otherwise die. About 80% of heart transplant patients are alive 2 years after the operation. At 5 years, 70% of patients will still be alive after a heart transplant.
The main problem, as with other transplants, is rejection. If rejection can be controlled, survival increases to over 10 years.

Cardiovascular system


The cardiovascular system consists of the heart, which is an anatomical pump, with its intricate conduits (arteries, veins, and capillaries) that traverse the whole human body carrying blood. The blood contains oxygen, nutrients, wastes, and immune and other functional cells that help provide for homeostasis and basic functions of human cells and organs.

The pumping action of the heart usually maintains a balance between cardiac output and venous return. Cardiac output (CO) is the amount of blood pumped out by each ventricle in one minute. The normal adult blood volume is 5 liters (a little over 1 gallon) and it usually passes through the heart once a minute. Note that cardiac output varies with the demands of the body.

The cardiac cycle refers to events that occur during one heart beat and is split into ventricular systole (contraction/ejection phase) and diastole (relaxation/filling phase). A normal heart rate is approximately 72 beats/minute, and the cardiac cycle spreads over 0.8 seconds. The heart sounds transmitted are due to closing of heart valves, and abnormal heart sounds, called murmurs, usually represent valve incompetency or abnormalities.

Blood is transported through the whole body by a continuum of blood vessels. Arteries are blood vessels that transport blood away from the heart, and veins transport the blood back to the heart. Capillaries carry blood to tissue cells and are the exchange sites of nutrients, gases, wastes, etc.

Heart
The heart is a muscular organ weighing between 250-350 grams located obliquely in the mediastinum. It functions as a pump supplying blood to the body and accepting it in return for transmission to the pulmonary circuit for gas exchange. The heart contains 4 chambers that essentially make up 2 sides of 2 chamber (atrium and ventricle) circuits; the left side chambers supply the systemic circulation, and the right side chambers supply the pulmonary circulation. The chambers of each side are separated by an atrioventricular valve (A-V valve). The left-sided chambers are separated by the mitral (bicuspid) valve, and right-sided chambers are divided by the tricuspid valve. Blood flows through the heart in only one direction enforced by a valvular system that regulates opening and closure of valves based on pressure gradients

Unique properties of cardiac muscle
Cardiac muscle cells are branching striated, uninucleate (single nucleus) cells that contain myofibrils.
Adjacent cardiac cells are connected by intercalated discs containing desmosomes and gap junctions. The myocardium behaves as a functional syncytium because of electrical coupling action provided by gap junctions.
Cardiac muscle has abundant mitochondria that depend on aerobic respiration primarily to generate adenosine tri-phosphate (ATP), the molecule that provides energy for cellular function

Systemic Circulation
The systemic circuit originates in the left side of the heart and functions by receiving oxygen-laden blood into the left atrium from the lungs and flows one way down into the left ventricle via the mitral valve. From the left ventricle, oxygen rich blood is pumped to all organs of the human body through the aortic semilunar valve
Pulmonary Circulation
The pulmonary circuit is on the right side of the heart and serves the function of gas exchange. Oxygen-poor systemic blood reaches the right atrium via 3 major venous structures: the superior vena cava, inferior vena cava, and coronary sinus. This blood is pumped down to the right ventricle via the tricuspid valve and eventually through the pulmonic valve,leading to the pulmonary trunk that takes the oxygen deprived blood to the lungs for gas exchange. Once gas exchange occurs in the lung tissue, the oxygen-laden blood is carried to the left atrium via the pulmonary veins, hence completing the pulmonary circuit (see the image above).

Coronary Circulation
Coronary circulation is the circulation to the heart organ itself. The right and left coronary arteries branch from the ascending aorta and, through their branches (anterior and posterior interventricular, marginal and circumflex arteries), supply the heart muscle (myocardial) tissue. Venous blood collected by the cardiac veins (great, middle, small, and anterior) flows into the coronary sinus. Delivery of oxygen-rich blood to the myocardial tissue occurs during the heart relaxation phase

Vessel Anatomy
An artery is a blood vessel that carries blood away from the heart to peripheral organs (see the image below). They are subdivided into larger conducting arteries, smaller distributing arteries, and the smallest arteries, known as arterioles, that supply the capillary bed (the site of active tissue cells gas exchange).

Capillaries are vessels that are microscopic in size and provide a site of gas, ion, nutrient, and cellular exchange between blood and interstitial fluid. They have fenestrations that allow for and enhance permeability for exchange of gas, ion, nutrient, and cellular elements
A vein is a blood vessel that has a larger lumen, and sometimes veins serve as blood reservoirs or capacitance vessels, containing valves that prevent backflow. This system of vessels in general returns blood to the heart from the periphery
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