Biology 12 Circulatory System Vocab

Carotid Artery

A branch of the aorta conducting blood to the head. There is a right and a left carotid artery. They are coupled with the jugular veins that conduct deoxygenated blood away from the head.

Left Ventricle

A chamber in the heart, the left ventricle is one of the pumping chambers. The left ventricle marks the beginning of the systemic circuit.

Blood Vessel

A tubular structure that carries blood. Generally, there are considered to be three types of blood vessels: arteries, capillaries and veins.

Arterial Duct

AKA Ductus Arteriosus. This fetal artery connects the pulmonary trunk to the aorta thus allowing some blood to bypass the nonfunctional lungs. After birth, the inner lining of the arterial duct begins to proliferate and closes the lumen. The duct is still evident in an adult heart as the arterial ligament (ligamentum arteriosus), which attaches the two major arteries together.

Venous Duct

AKA Ductus Venosus. Tube like portion of the umbilical vein that courses through the liver, thus fetal blood can bypass the functions of the liver. This is essential so it can get to the heart and be pumped around the fetal body. After birth the venous duct atrophies.

Red Blood Cells

AKA Erythrocytes. Small cells that are mass produced by the red bone marrow. These cells are biconcave and anucleate (without a nucleus), thus they have a relatively short life span of about 120 days. Worn out and dead red blood cells are significant because they contain hemoglobin, which can differentially transport oxygen, carbon dioxide, and hydrogen in the blood. As with other cells, red blood cells have genetic markers (glycoproteins) called antigens. Differences among glycoproteins constitute the difference between blood types.

Posterior Vena Cava

AKA Infererior Vena Cava. Major vein that drains the blood from the body regions posterior to the heart. All the venules in the lower regions of the body contribute blood to the posterior vena cava, which ends at the right atrium.

White Blood Cells

AKA Leukocyte. Blood cells that combat infection. There are several types of white blood cells, all produced from bone marrow, but specialized in different ways to provide the body with a variety of mechanisms to combat infection. These mechanisms include phagocytosis, releasing antibodies to cause agglutination, releasing enzymes that destroy foreign cell membranes etc. Generally speaking white blood cells are about twice the size of red blood cells, are not as abundant and often have cytoplasmic granules and a complex shaped nucleus.

Systolic Pressure

AKA Systole. Force of blood outwards on the arteries when the ventricles are contracting, as opposed to diastolic, which is the pressure between contractions. Normally systolic pressure is in the range of 120mmHg.

Platelets

AKA Thrombocyte. Type of blood cell formed by the fragmentation of a megakaryotype (large cell from bone marrow). Platelets function for blood clotting. When damaged, they release thromboplastin, an enzyme that begins a cascade of reactions ending with the formation of a blood clot.

Autonomic Nervous System

ANS is a sub-division of the nervous system. The ANS is strictly an effector system consisting of sets of two motor neurons joined by synapses leading to specific effectors (smooth muscles or glands). These neurons are not under voluntary control, functioning involuntarily (automatically) instead. The ANS is subdivided into the sympathetic and parasympathetic neurons, which have very significant differences.

Lymphatic Veins

Although lymphatic vessels are similar in structure to and generally found alongside blood vessels, they are also different from blood vessels. Lymph vessels are larger than blood vessels. Unlike blood, lymph within lymphatic vessels is not circulated in the body. While cardiovascular system structures pump and circulate blood, lymph flows in one direction and is ushered along by muscle contractions within lymph vessels, valves that prevent fluid back flow, skeletal muscle movement, and changes in pressure. Lymph is first taken up by lymphatic capillaries and flows to lymphatic vessels. Lymphatic vessels direct lymph to lymph nodes and along to lymphatic trunks. Lymphatic trunks drain into one of two lymphatic ducts, which return lymph to the blood via the subclavian veins.

Pulmonary Trunk

Artery that leaves the right ventricle. It branches to become the right and left pulmonary arteries.

Veins

Blood Vessels that return blood towards the heart. Veins have valves to prevent the backflow of blood.

Renal Artery

Blood vessels of the kidneys. The renal artery is a branch of the aorta and conducts blood into a kidney.

Coronary Artery

Blood vessels that serve the heart muscle. The coronary artery describes the initial branches of the aorta going directly to the heart muscle as the aorta ascends out of the left ventricle.

Coronary Vein

Blood vessels that serve the heart muscle. the coronary vein is a set of veins that conduct blood from the heart tissue to the vena cavae as it enters the right atrium.

Mesenteric Artery

Blood vessels that that service the intestines.

Subclavian Vein

Blood vessels that travel under the clavicle (collar bone). Subclavian vein returns the blood back to the right atrium

Subclavian Artery

Blood vessels that travel under the clavicle (collar bone). The subclavian arteries are branches of the aorta that take blood to the body walls and shoulder areas. The brachial artery is a branch of the subclavian artery.

Right Ventricle

Chamber such as in the heart and the brain. In the heart, the ventricles are the pumping chambers. The right ventricle marks the beginning of the pulmonary circuit.

Septum

Dividing wall. There is more that one reference. (1) The heart has a septum that divides the ventricle chambers. In this case the septum is a thick muscular wall of both chambers. The purkinje fibres, which cause the ventricle contractions, run down the septum. (2) Dividing wall of the nostril. Made out of cartilage.

Plasma

Fluid portion of blood. Plasma is mostly water (91%), and includes globulins (proteins from the liver), nutrients, wastes, cholestrol, steroid hormones, dissolved gases and various ions.

Blood Pressure

Force that blood (in the lumen of blood vessels) exerts on blood vessel walls. Blood pressure is variable in arteries due to the pumping action pf the heart (produces the "pulse") and diminishes with distance from the heart. Blood pressure is is measured in units called mmHg (millimetres of mercury). Blood pressure is normally measured in the brachial artery of the arm, where an average reading is considered (120/80) (systolic over diastolic). Blood pressure is affected by a variety of factors, such as stress, diet, genetics, exercise, the presence of plaque on arterial walls, etc.

Atrioventricular Valve (AV)

Large valves made out of muscle and connective tissue that allow blood to pass from the atria to the ventricles of the heart, but not the other way. These valves are closed during systole and opened during diastole. The AV valves are equipped with chordae tendineae to prevent them from inverting during systole.

Aorta

Largest artery of the body, which conducts oxygenated blood out of the left ventricle. Branches of this artery include the coronary, carotid, and subclavian arteries before it loops behind the heart and becomes known as the dorsal aorta. The loop portion, called the aortic arch, is specialized with aortic bodies containing chemoreceptors sensitive to the pH, oxygen and carbon dioxide content in blood and baroreceptors sensitive to blood pressure. These receptors stimulate appropriate responses to help maintain homeostasis.

Anterior Vena Cava

Major veins that conduct blood into the right atrium. The anterior (superior) vena cava drains blood from the anterior regions of the body (above the heart).

Hypertension

Means high blood pressure.

Hypotension

Means low blood pressure.

Lymph Capillaries

Minute beginnings of lymph ducts that are located in tissue spaces of the body. These capillaries absorb fluids that become lymph. The lacteals are specialized lymph capillaries that are located in the villi of the ileum, where they absorb fats.

Purkinje Fibres

Nerve tracts that begin at the AV node in the right atrium, extend down the septum of the heart and out into the massive muscular walls of the ventricles. The ventricular contractions are coordinated because of the simultaneous delivery of impulses by these nerves.

Sinoatrial Node (SA)

One of the two nodes of the heart. The other is the AV node; both are located in the right atrium. These hear nodes are unique in that they are a combination of nervous tissue and muscle tissue, which allows them to initiate contractions. The SA node is also called the pacemaker of the heart because it is responsible for the intrinsic (unassisted) heart rate of approximately 72beats/minute. It causes the contraction of the atria and sends an impulse to the AV node to stimulate its activity. The AV node sends down impulses down to the purkinje fibres causing the contraction of the ventricles. The SA node is also connected to the medulla oblongata by both sympathetic and parasympathetic nerve fibres. The sympathetic will increase its activity, where the parasympathetic will decrease its activity.

Atrioventricular Node (AV)

One of two pieces of nodal tissue in the heart. The AV node is under the influence of impulses from the SA node. It generates impulses that travel through a nerve bundle (bundle of His) down the septum to a branching set of nerve fibres, called Purkinje fibres. These innervate the ventricles, thus coordinating their contraction.

Systemic Circulation

Part of the circulatory system that delivers oxygenated blood to the body cells. It starts at the left ventricle and ends at the right atrium.

Pulmonary Circulation

Portion of the circulatory system that related to the lungs. The pulmonary circuit begins at the right ventricle which pumps blood through the pulmonary trunk and into the two pulmonary arteries. It includes the pulmonary capillaries, where external respiration takes place, and the pulmonary veins, which conduct oxygenated blood to the left atrium.

Left Atrium

Receiving chambers of the heart on the left side. The atria pass blood along to the ventricles to be pumped out of the heart. They are separated from the ventricles by AV valves.

Right Atrium

Receiving chambers of the heart. The atria pass blood along to the ventricles to be pumped out of the heart. The are separated by AV valves. Deoxygenated blood enters the right atrium through the inferior and superior vena cava.

Fetal Circulation

Refers to the circulatory pattern of an unborn mammal. During gestation (development) the lungs do not function for gas exchange. As a result, the fetus must conduct external respiration via placenta, and have a system that is designed to divert blood away from the lungs.

Pulmonary Arteries

Right and left pulmonary arteries conduct blood to the right and left lungs, respectively. These are branches of the pulmonary trunk, which conducts blood out of the right ventricle.

Chordae Tendineae

Small tendons which attach the AV valves to muscular extensions from the inside walls of the ventricles. These tendons prevent the AV valve flaps form inverting during systole (ventricular contraction)

Lymph Nodes

Spots along thelymph ducts, usually where two or more ducts join together. These nodes house white blood cells, which are active in the destruction of foreign and potentially harmful cells and substances transported by the lymph before it is added to the circulatory system.

Valve

Structures that control the movement of fluids along a tube. Sphincter muscles are often called valves. Veins, the heart and the lymphatic system contain valves to prevent backflow of the fluid they contain.

Antigen

Substance capable of stimulating the release of antibodies (the immune response). In some cases, antigens are simply chemical substances (toxins). In other cases, they are cell markers such as glycoproteins and glycolipids. The interaction between antibodies and antigens is called agglutination.

Lymphatic System

System made up of all the vessels and nodes that transport and clean lymph. The lymph ducts all eventually join together to produce the main lymphatic system ducts that join the circulatory system. The junction of the lymphatic system and the circulatory system is close to where the right subclavian vein meets the superior vena cava.

Capillary-Tissue Fluid Exchange

The exchange of fluid materials between blood in a capillary and extracellular fluids in tissues as the blood travels through a capillary bed. At the arteriole side of the capillary bed, the blood pressure is still sufficiently high (35 mmHg) to force water and some small substances out of the capillaries into the tissue spaces. Oxygen and nutrients are readily transported down their respective concentration gradients into the cells. Meanwhile, this movement creates an osmotic gradient that draws water back into the capillary at the venule end. The water that is returned now transports substances that are found in abundance in the extracellular fluids, namely CO2 and NH3. Under normal circumstances, there is no net change in fluid volume of the blood.

Iliac Artery

The major blood vessels of the legs. The dorsal aorta branches to form the iliac arteries where the iliac veins join together to form the inferior (posterior) vena cava. The umbilical arteries (fetal) are branches of the iliac arteries.

Iliac Vein

The major blood vessels of the legs. Where the iliac veins join together to form the inferior (posterior) vena cava, the dorsal aorta branches to form the iliac arteries.

Hepatic Vein

The major vein that conducts blood from the liver back into the inferior vena cava. On its way through the liver, the blood is treated or conditioned in several ways such as: regulation of the glucose level, removal of damaged blood cells, removal of toxins such as alcohol, and addition of globulins such a blood clotting proteins.

Hepatic Portal Vein

The major vein that takes nutrient-rich blood from the small intestines to the liver. Portal veins are distinct in that they have capillary beds on both ends. On the intestinal end, this vein receives the glucose and amino acids from digestion and conducts them to the liver. The liver tissue does several things to the blood, including removing excess glucose (above the normal level) and storing it as glycogen.

Diastolic Pressure

The pressure that blood exerts outwards on the walls of arteries when the heart is not contracting. Normal diastolic pressure measures about 80 mmHg at the brachial artery. As with systolic pressure, it decreases with increasing distance from the heart.

Pulmonary Veins

The pulmonary veins conduct blood from the lungs to the left atrium.

Renal Vein

The renal vein conducts blood out of a kidney and into the posterior (inferior) vena cava.

Blood Velocity

The speed of blood through a blood vessel. Blood velocity is highest and most variable in arteries. It is slowest in capillaries, which maximizes the time for capillary-tissue fluid exchange. Velocity in veins is a result of muscle activity as there is very little blood pressure pushing the blood back to the heart.

Jugular Vein

The veins that conduct blood from the head down the neck. They join the superior vena cava allowing the blood to enter the right atrium so it can be pumped into the pulmonary circuit.

Blood

Type of connective tissue consisting of plasma and formed elements. In general, blood has four functions: transport nutrients and wastes, combat infection, forming blood clots, and regulation of body temperature.

Oval Opening

Valve allowing blood to pass from the right ventricle of a fetal heart into the left ventricle, thus the blood bypasses the non-functional lungs. Once the lungs inflate (first breath), significant volume of blood enters the left ventricle via the pulmonary veins. This forces the valve closed, and in a few days the tissues of the valve knit together, sealing the valve shut.

Semi-Lunar Valve

Valves throughout which blood must pass to exit the heart. As such, there is a semi-lunar valves at the beginning of the aorta (called the aortic valve) and one at the beginning of the pulmonary artery (called the pulmonary valve). Semi-lunar valves prevent the backflow of blood into the ventricles.

Umbilical Artery

Vascular components of the umbilical cord that conduct relatively deoxygenated blood and wastes from the iliac arteries to the placenta.

Antibody

Y-shaped proteins that are released by a particular type of white blood cell known as a Bcell lymphocyte in response to the presence of foreign antigens. Antibodies bond onto these antigens causing agglutination.