Circulatory System

 A system made up of three parts: Heart Blood vessels Blood  Transport nutrients and gases to different parts of the body where they can be used by the cells  Transport waste for removal along with excretory system

Types of Blood Vessels  Artery: a muscular blood vessel that carries blood away from the heart. Arteriole: a small arterial branch that delivers blood directly to a capillary bed.  Vein: one of the blood vessels that carries blood to the heart. Venule : a small venous branch that carries blood from a capillary bed to a vein.  Capillary: the smallest blood vessel that allows oxygen to be exchanged.

Components of Blood

 Plasma- fluid part of blood  White blood cells- destroy bacteria and viruses  Platelets- made from bone marrow and repair damaged areas of your body  Red Blood Cells- oxygen carries

Structures of the heart

The Heart  Two sides separated by a thick wall Each side has an atrium and a ventricle  Atrium: receives blood entering the heart  Ventricle: pumps blood from the heart to the rest of the body One way valves (their closing makes your heartbeat)  A double pump Right side = pumps blood to the lungs Left side = pumps blood to the rest of the body

Regulation of Heart Beat  Heart beat varies from person to person…why?  Pacemaker- located in the right atrium, this group of cells regulate the rate at which the cardiac muscles contract (SA Node)  Brain Stem regulates heart rate, but pacemaker works independently

The impulse then travels to a large bundle of Purkinje fibers called the Bundle of His, where they move quickly to the septum that divides the two ventricles. With the AV node holding up the impulse just enough to let the atria finish their contraction before the ventricles begin to contract, blood can fill the ventricles. Atrioventricular node. When the SA node initiates a contraction, Purkinje fibers rapidly conduct the impulse to another site near the bottom of the right atrium and near the center of the heart. This region is the AV node, and slows the impulse briefly. Sinoatrial node is located in the wall of the right atrium, near the junction of the atrium and the superior vena cava. contracts on its own about 72 times per minute. The “pacemaker” of the heart because it contracts the most in a minute and because cardiac muscle cells are connected to each other by intercalated discs And, since the Purkinje fibers have carried the impulse to the apex of the ventricles first, the contraction proceeds from the bottom of the ventricles to the top where the blood leaves the ventricles through the pulmonary arteries and the aorta. Purkinje fibers (conduct impulses 5x more rapidly than surrounding cells) form a pathway for conduction of the impulse that ensures that the heart muscle cells contract in the most efficient pattern.

The cardiac cycle The contraction of the heart cause the distinctive sounds heard when listening to the heart with a stethoscope. The "lub- dub" sound is the sound of the valves in the heart closing. When the atria end their contraction and the ventricles begin to contract, the blood is forced back against the valves between the atria and the ventricles, causing the valves to close. This is the "lub" sound, and signals the beginning of ventricular contraction, known as systole. The "dub" is the sound of the valves closing between the ventricles and their arteries, and signals the beginning of ventricular relaxation, known as diastole.

Pulmonary and Systemic Circulations  Pulmonary Circulation: the pathway that blood follows from the heart to the lungs (right side of the heart)  Systemic Circulation: the route that blood travels from the heart to most of the body and then back to the heart (left side of the heart)

 Left side of the heart  Larger in size (must pump blood to the rest of the body)  blood leaves through the aorta, goes to all the organs of the body through the systemic arteries, and then returns to the heart through the systemic veins Pulmonary Circuit  Right side of the heart  Smaller in size (only pumps blood to the lungs)  blood leaves the heart through the pulmonary arteries, goes to the lungs, and returns to the heart through the pulmonary veins. The Pulmonary and Systemic Circuits Systemic Circuit

"When it leaves the right, it comes right back, but when it leaves the left, it has left for good."

How does the heart get blood?  Coronary arteries arise from the aorta right after it leaves the heart. branch into capillary beds that course throughout the heart walls and supply the heart muscle with oxygenated blood.  Coronary Veins return blood from the heart muscle, empty directly into the right atrium.

Flow of blood through the body Right ventricle  pulmonary arteries  Lungs  pulmonary veins  left atrium  left ventricle  aorta  arteries  capillaries  veins  vena cavas  right atrium  right ventricle g/heart.gif

Blood Types  Blood type- classification based on whether certain proteins are present on the surface of the red blood cells.  Types A, B, O, or AB  If different blood types are mixed, RBC’s will clump together  RH Factor- determines a blood type is in a blood group (positive or negative)

How is your blood type determined?  Each biological parent donates one of their two ABO alleles to their child. A mother who is blood type O can only pass an O allele A father who is blood type AB could pass either an A or a B allele  This couple could have children of either blood type A (O from mother and A from father) or blood type B (O from mother and B from father). Remember the father has a greater genetic influence than the mother! Rh+ = Rh+/Rh+ or Rh+/Rh- Rh-= Rh-/Rh-  Just like the ABO alleles, each biological parent donates one of their two Rh alleles to their child. A mother who is Rh- can only pass an Rh- allele A father who is Rh+ could pass either an Rh+ or Rh- allele  This couple could have Rh+ children (Rh- from mother and Rh+ from father) or Rh- children (Rh- from mother and Rh- from father).

Chances of having a specific blood type: Parent 1 AB BAAOOO Parent 2 ABBAOBBABAO OXXXXXX AXXXXXXX BXXXXXXX XXXX

Tutorial (class on Wednesday)  an_bio/problem_sets/blood_types/Int ro.html an_bio/problem_sets/blood_types/Int ro.html  GOOD RESOURCE: art+and+Lungs art+and+Lungs