The Circulatory System

Circulatory System

transport necessary materials to cells and waste materials away from cells in the body. Blood is the major transport material in a circulatory system. The heart serves as the major pump that pushes blood through blood vessels in the body of the animal

Open circulatory system

blood (hemolymph) is pumped into a body cavity (hemocoel) and bathes organs directly. These are no blood vessels associated with open circulatory systems. Nutrient and waste exchange occurs entirely by diffusion between the hemolymph and the body cells. Most invertebrates exhibit an open circulatory system

Disadvantages of Open Circulatory Systems

Blood is not delivered directly to areas that are metabolically active. Blood flow is inefficient in these systems

Closed Circulatory Systems

in these systems, blood is pumped throughout the body of the organism through blood vessels. A muscular heart serves as the primary pump in these types of circulatory systems

Advantages of Closed Circulatory Systems

They can be adjusted to match the metabolic demands of organs. They can grow in size with the organism. They can repair themselves (up to a point when injured). Earthworms, Cephalopods, and Vertebrates all have closed circulatory systems

Single Circulatory System

in these systems, a 2 chambered heart is present. These types of hearts have one atrium (that receives blood from the body) and one ventricle (that pumps blood to the body). Fishes exhibit a single circulation system

Double Circulatory System

in these systems a 4 chambered heart (with 2 atria and 2 ventricles) is present. Specifically, in double circulation, oxygenated and deoxygenated blood are separated into two circuits, the systemic circulation and the pulmonary circulation

Pulmonary Circulation

the right side of the heart pumps blood to the lungs where gas exchange occurs

Systemic Circulation

the left side of the heart pumps blood through the body

Blood

serves as the transport medium in closed circulatory systems. Carries nutrients and oxygen to all cells and it removes waste products and carbon dioxide

Plasma

the straw colored liquid portion of blood. Plasma is composed of primarily of water along with numerous materials that are dissolved in the water. Top layer

Leukocytes (White Blood Cells)

These form the white layer (known as the buffy coat) under the Plasma. These blood cells play a key role in fighting infection and providing immunity for animals

Erythrocytes (Red Blood Cells)

These are the cells located at the base of a spun test tube. Carry oxygen to the body tissues. Most abundant cells in the body. Hemoglobin makes them red

Hemoglobin

red pigment. Is composed of a protein known as globin that surrounds and supports a heme molecule. The Heme molecule contains a central iron atom. Then oxygen is on top of that

Thrombocytes (Platelets)

These contain granules that store numerous agents involved in clot formation

Steps in Clot Formation

Vascular spasm, platelet plug formation, and coagulation

Vascular Spasm

occurs when smooth muscle is broken blood vessels contract to limit blood loss

Platelet Plug Formation

platelets become sticky following an injury. The platelets will begin to stick to collagen fibbers in broken blood vessel to form a plug which reduce blood loss.

Coagulation

occurs as platelets release chemicals that stimulate the formation of clot

Vertebrate hearts

we are going to examine the vertebrate hearts that carry out double circulation. Recall that these hearts have two atria and two ventricles

Myogenic Heart

heart muscle contraction (beats) are created by nerve impulses and autorhythmic cells in the heart

Atria (singular: atrium)

The upper chambers. The atria are receiving chambers for blood returning to the heart from the body. They collect blood and then they push the blood into the ventricles. Atria are thin walled since they only push blood into the ventricles. They do little to move blood through the body. Primary function is to receive incoming blood from the body

Superior vena cava

returns blood from regions superior to the diaphragm

Inferior Vena Cava

returns blood from region inferior to the diaphragm

Coronary sulcus

collects blood returning from the myocardium itself

4 Pulmonary Veins

carry blood to the hearts left atrium. These veins carry blood from the lungs back to the heart. This blood is oxygenated blood (this is the only area in the human body where a vein carries oxygenated blood

Ventricles

lower heart chambers; these make up most of the mass of the heart. The lower chambers. Pump blood to the body making them more muscular.

Atrioventricular (AV) Valves

2 of these; 1 located between each atrium and ventricle. These prevent blood back flow

Tricuspid Valve

consists of 3 flaps or cusps and is located between the right atrium and right ventricle. The flaps are primarily connective tissue

The Bicuspid Valve

consists of only 2 flaps and it is located between the left atrium and left ventricle. It is also known as the Mitral Valve

Chordae Tendinae and Papillary muscles

The flaps of the valves are attached to cordlike chordae tendinae that attach to the papillary muscles that line the inside of the ventricles. The chordae tendinae and papillary muscles together control the AV valves

Semilunar (SL) Valves

2 of these, located between the ventricles and the major arteries attached to the heart. These prevent blood from back flowing into the ventricles. Each SL valve is composed of 3 half moon shaped cusps. When the ventricles contract, the blood pushes the SL valves open (against the walls of the arteries). When the ventricles relax, blood in the arteries pushes the valves closed. This are the Pulmonary Semilunar Valve and Aortic Semilunar Valve

Pulmonary Circulation

carried out by the right side of the heart. In this circulation, blood is pumped to the lungs and back to the left side of the heart.

Systemic Circulation

carried out by the left side of the heart. In this circulation pattern, blood is pumped to and from the body

Coronary Circulation

blood flow to and from the heart muscle

Pulmonary Circulation

Blood enters the right atrium via the superior and inferior vena cava. This is deoxygenated blood. The right atrium contracts. This pushes blood past the tricuspid valve to the right ventricle. Once blood fills the right ventricle, then the tricuspid valve closes to prevent the backflow of blood. The right ventricle contracts to push blood. The oxygenated blood returns to the left atrium

Systemic Circulation

The left atrium contacts to force blood past the mitral valve to the left of the ventricle. Once the left ventricle is filled with blood, the mitral valve closes to prevent the back flow of blood. The left ventricle contracts to force blood past the aortic semilunar valve into the aorta and on to all parts of the body

Coronary Arteries/Coronary Circulation

carry oxygenated blood to the myocardium. These arteries encircle the heart. Deoxygenated blood from the myocardium empties into cardiac veins which empty into the right atrium

Myocardial Infraction

heart attack or coronary

Infraction

death of tissues due to interrupted blood supply. This is often caused by a blockage in ones coronary arteries

Control of Heart Activity

The Medulla oblongata controls and regulates much of the hearts activity. Specifically, the medulla oblongata controls the cardiovascular center and the cardio accelerating center

The Cardiac Cycle

refers to the event that occur during one complete heartbeat. The 2 atria contract while the 2 ventricles relax and then vis versa. On average the heart beats 70-75 times per minute

Systole

refers to contraction and emptying of heart chambers

Diastole

refers to relaxing and filling of heart chambers

Lubb

produced by the closing of the atrioventricular valves during ventricular systole. Ventricular pressure is greater than artrial pressure at this point

Dubb

2nd heart sound. Occurs at the end of ventricular systole as the semilunar valves close

EKG

a measurement of the heart

P Wave

1st wave, is very small. This wave is the result of atrial depolarization

QRS Complex

large results from ventricular depolarization (contractions)

T Wave

3rd wave, represents ventricular repolarization (relaxation)

Blood Vessels

responsible for delivering blood to all parts of the human body. Blood goes to veins and then comes back to heart

Arteries

carry blood away from the heart. Mostly oxygenated blood

Tunica Interna

Innermost layer. Also known as the tunica intima. surrounds a central blood containing space known as the lumen

Tunica Media

composed primarily of smooth muscle tissue. Thickest layer in the wall of arteries. Also regulates blood pressure and flow

Vasoconstriction/Vasodilation

reduction in lumen diameter due to smooth muscle contraction. widening of the lumen due to smooth muscle relaxation

Tunica Externa

outermost layer of the arterial wall. Is primarily connective tissue

Capillaries

microscopic blood vessels. Smallest in the body. only one thick layer and primary sites for exchange of materials

Veins

carry deoxygenated blood back to the heart. Sluggish at best. thinner walls and contain valves to prevent back flow

Blood Flow

volume of blood flowing through a vessel or organ in a given period of time

Blood Pressure

the force per unit area exerted on the wall of a blood vessel by its contained blood

Resistance

the opposition to blood flow. This also includes any friction blood faces as it travels through the body

Blood Viscosity

refers to the thickness of blood

Blood Pressure

associated with arteries. Is measured with a sphygmomanometer

Systolic Pressure

Caused by ventricular contraction. typically measured around 120mmHg

Diastolic Pressure

the lowest blood pressure reading 60-80

Vasomotor center

in the medulla of the brain

Baroreceptors

located in most large arteries. Thes stretch when BP increase which creates impulses that are sent to the vasomotor center. The vasomotor center responds by decreasing blood pressure