DAT Biology: Circulatory System

Heart

Pump at the center of the circulatory system, responsible for making sure that the body tissues have access to required nutrients and gases are carried in blood

Right Atrium

Receives deoxygenated blood from the superior vena cava and inferior vena cava

Superior Vena Cava

Collects deoxygenated blood from the chest, arms, head, and neck

Inferior Vena Cava

Collects deoxygenated blood from the abdomen, pelvis, and lower limbs

Right Atrioventricular (AV) Valve (Tricupsid Valve)

Allows blood to pass from the right atrium to the right ventricle

Right Ventricle

Pumps deoxygenated blood into the pulmonary artery

Pulmonary Artery

Carries deoxygenated blood to the lungs

Pulmonary Semilunar Valve

Allows blood to pass from the right ventricle into the pulmonary artery

Right Ventricular Contraction

Tricuspid valve closes and the pulmonary semilunar valve opens, allowing for ventricular emptying without backflow into the atrium

Right Ventricular Relaxation

Tricuspid valve opens and the pulmonary semilunar valve closes, allowing for ventricular filling from the atrium only without backflow from the pulmonary artery

Left Atrium

Receives oxygenated blood from the pulmonary vein

Pulmonary Vein

Carries oxygenated blood from the lungs to the heart

Left Atrioventricular (AV) Valve

Bicuspid or mitral valve, allowing oxygenated blood to flow from the left atrium to the left ventricle

Left Ventricle

Pumps oxygenated blood into the aorta, it is the most muscular chamber of the heart, and the contraction will generate more pressure than that of the right ventricle

Aorta

Directs oxygenated blood from the heart into the systemic circulation

Pulmonary Circulation

Transports deoxygenated blood from the heart to the lungs via the pulmonary artery and oxygenated blood from the lungs back to the heart via the pulmonary veins

Systemic Circulation

Transports oxygenated blood from the heart to the body via the aorta and deoxygenated blood from the body to the heart via the superior and inferior vena cava

Cardiac Rhythm

Heart contracting and relaxing in a rhythmic pattern to ensure the most efficient transfer of blood

• Proper relaxation of a heart chamber allows for maximal filling

• Proper contraction after filling allows for maximal ejection of blood

Cardiomyocytes

Heart Muscle Cells

Automaticity

Ability of cardiac cells to generate electrical impulses spontaneously without external stimulation

Sinoatrial (SA) Node

Pacemaker of the heart

Located in the upper wall of the right atrium, has greatest automaticity (most likely to reach threshold and initiate an action potential), simultaneously stimulates contraction of the right and left atra, and transmits the electrical signal to the AV node

Atrioventricular (AV) Node

Briefly delays the electrical current coming from the SA node

• Delay allowing the ventricles time to fill before the signal to contract is sent to the ventricles

• Located in the lower wall of the right atrium

• Passes electrical signal to the Bundle of His

Bundle of His

Passes the signal from the AV node to the bundle left and right bundle branches

Purkinje Fibers

Receive electrical signal from the bundle branches and stimulates ventricular contraction

Intercalated Disks

Cell junctions between cardiomycotes, providing physical/electrical connection (gap junctions), allowing the contraction signal to be propagated in a coordinated, rhythmic fashion

Systole

Ventricular Ejection Phase

Ventricles contract, increasing the pressure within the chambers until it is enough to push open the semilunar valves, blood enters the pulmonary and systemic arteries, and arteriol blood pressure is at its highest during systole, the artery with the highest pressure during systole is aorta

Diastole

Ventricular Filling Phase

Ventricular myocardium relaxes, allowing a maximal amount of blood to fill each chamber from the atria, and arterial blood pressure is at its lowest point

Cardiac Output

Volume of blood being pumped by the heart per minute

Heart Rate X Stroke Volume

Heart Rate

How fast the heart beats (beats/minute)

Stroke Volume

Volume ejected per single beat, calculated by subtracting end systolic volume from end diastolic volume

Blood Vessels

Transport blodo to and from the heart, helping to form a closed circulatory system with the heart

Arteries

Transport blood away from the heart

• Pressure highest in the arteries due to the hydrostatic pressure of the heart

• Carry oxygenated blood in the systemic circulation

• Carry deoxygenated blood in the pulmonary circulation

Arteriole

Branches off of arteries with smaller diameters than their parent arteries

Greatest drop in bp is when going from arteries to arterioles

Capillaries

One-cell-thick branches off of arterioles, connecting the arterial and venous circulations

• Exchange gases and nutrients by diffusion

• Body Tissues: Collect waste and CO2, deposit O2 and nutrients

• Lungs: deposit CO2 and collect O2

Venules

Intermittent vessel that transports blood from the capillaries to the veins

Veins

Transport blood towards the heart

• Venous circulation holds more blood tha the arterial circulation and veins have lower pressure than arteries

• Veins have valves (pocket or venous valves) to prevent back flow in the low pressure system

• Contraction of the surrounding skeletal muscles is used to generate the pressure necessary to push blood through the veins

Blood Plasma

Fluid component of blood

Composed of waterm proteins, nutrients,hormones, and other water soluble substances

Makes up most of the blood by volume (55%)

White Blood Cells (Leukocytes)

Cells of the immune system that defend against infection

Travel to site of infectino through blodo and enter the infected tissue to mount a response against the invading pathogens

Neutrophil

Most common white blood cell

Platelets

Aka thrombocytes, immune cells, anucleate, cytoplasmic cell fragments responsible for clotting

Release clotting factors helping to turn fibrinogen into fibrin, creating a net to stop bleeding

Megakaryocytes

Large, platelet precursor/parent cells that are bone marrow residents

Vitamin K

Necessary cofactor for several clotting factors; deficiency can lead to a bleeding disorder

Red Blood Cells (Erthrocytes)

Responsible for transporting gases via hemoglobin proteins, making up 45% of blood volume

Transports O2 from the lungs to the tissues and CO2 from the tissues to the lungs

Bioncave Disk Shape

Bioncave Disk Shape

Looks like donut without the hole, just the indentation

Blood Clotting

A protective mechanism meant to repair damage to blood vessels and prevent extensive bleeding

Tears in blood vessels initiate blood clotting cascade helping to plug the tear, sealing it off to prevent further leakage

Blood Clotting Cascade

Positive Feedback Mechanism

Damaged Tissues signal for platelet accumulation, each platelet then signals for the attraction and activation of other platelets

Tissue Damage

A tear occurs in the blood vessel wall, exposing structural collagen

Platelet Activation

Exposed collagen initiates platelet adhesion and activation

Platelet Plug

Accumulation of aggregated platelets that initially plug the tear

Activated Platelets

Release clotting factors converting prothrombin (inactive form) into thrombin (active form)

Clot Formation

Activated thrombin converts fibrinogen (inactive form) into fibrin (active form)

Activated fibrin strands polymerize together, forming the hemostatic plug

Hemostatic Plug

Blood clot made of fibrin meshwork and attached platelets

RBC Antigens

Sugar and protein identity markign molecules on cells

Type A

RBCs have the A antigen

Type B

RBCs have the B antigen

Type AB

RBCs have both the A and B antigens

Type O

RBCs have neither the A or B antigens

Agglutination

Clumping together of red blood cells and red blood cell antibodies, caused by receiving an incorrect blood type

Rhesus Factor

Additional red blood cell surface marker with two phenotypes: Rh + and Rh -

Rh + donors cannot give blood to Rh - because the foreign Rh antigens will promote an immune response in the receiving, attacking it, rendering it ineffective

Universal Donors

Blood donors who can donate blood to anyone, type O (-) blood

Type O (-)

Universal Donor: red blood cells that do not have A, B, or Rh antigens

No red blood cell antigens are present to stimulate an immune response in the receiving patient

Universial Acceptor

Patients who can receive blood from anyone (can receive any blood type)

Type AB (+)

Type AB (+)

AB (+) red blood cell have the A, B, and Rh antigens, and the host immune system will be familiar with all three, so no immune response will be stimulated by any of the three antigens

Placenta

Source of fetal nutrients from the mother, delivered via the umbilical cord: barrier for gas/nutrient exchange

Umbilical Cord

Houses the umbilical vein and umbilical artery

Umbilical Vein

Carries oxygenated blood from the placenta to the fetal heart

Umbilical Artery

Carries deoxygenated blood from the fetal heart back to the placenta

Removes wastes and CO2 from the fetal circulation

Fetal Circulatory Shunts

Fetal lungs and liver are nonfunctional/liquid-filled, so they help to ensure the fetus gets oxygen to its brain without wasting energy trying to pump blood into fluid-filled, collapsed lungs or liver that palcenta is alrfeady taking care of; overall just more efficient

Ductus Venosus

A duct connecting the umbilical vein to the inferior vena cava

Blood passing through this duct will bypass the nonfunctional liver

Foramen Ovale

A hole connecting the right and left atria, blood is allowed to flow from the right to the left atrium, the right ventricle wants to pump blood to the lungs but the fetal lungs are nonfunctional, so blood passing through this duct bypasses the pulmonary circulation

Ductus Arteriosus

A duct that connects the pulmonary artery to the aorta

Some blood is inevitably pumped by the right ventricle into the pulmonary artery, so it allows blodo to still bypass the pulmonary circulation

Erythroblastosis Fetallis

Disorder initiated by a Rh (-) mother carrying an Rh (+) fetus, becomes problematic upon a second pregnancy with another Rh (+) fetus

Lymphatic System

Subsystem of the circulatory system that regulates fluid levels and produces immune cells

Thymus

Major immune center within the lympathic system

Location of T cell lymphocyte maturation

Spleen

Site of blood filtration within lymphatic system, filtering blood for pathogens and recycles old red blood cells

Hydrostatic Pressure

Pushes fluid out of the blood vessels (arterial end) and into the interstitial space, pressure exerted by vessel fluid

Oncotic Pressure

Brings fluid back into the capillary (venous end), type of osmotic pressure

Proteins on one side of a membrane pull water across to that side, protein concentrations higher in the blood than in the interstitium, blood protein oncotic pressure pulls fluid back into capillaries, not all fluid is reabsorbed from the interstitial space

Lymph

Consists of remaining fluid in the interstitial space, bacteria, fats, and proteins

Lymphatic Capillaries

Colelcts the lymph out of the interstitial space, merging to form larger vessels that travel to the heart

Lymph Nodes

Centers for the immune system to eliminate infections, lymph traveling to the heart is filtered through lymph nodes

Lymphatic Vessels

No pressure, similar to veins, valves in them to prevent backflow

Lymph Propulsion

Relies on contraction of surrounding skeletal muscle and smooth muscle, achieved via peristalsis

Peristalsis

Involuintary, wave-like contraction and relaxation of smooth muscles lining the digestive tract propelling food, liquids, waste forward through the esophagus, stomach, and intestines