Circulatory+immunity practice

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Questions and Answers

What are the three major components of the circulatory system?

The heart, blood vessels, and blood.

What is the function of the heart?

The heart is an organ that pumps blood through the body.

What are blood vessels?

Blood vessels are pathways for blood to travel through.

What is the function of blood?

Blood carries nutrients, gases, water, wastes, and other materials throughout the body. Signup and view all the answers

Which chamber of the heart is responsible for pumping oxygen-rich blood to the body?

Left ventricle Signup and view all the answers

Which of the following is NOT a function of the circulatory system?

Production of red blood cells Signup and view all the answers

Match the following heart structures with their functions:

Superior vena cava = Collects oxygen-poor blood from the head, chest, and arms. Inferior vena cava = Collects oxygen-poor blood from parts of the body below the heart. Pulmonary arteries = Carry oxygen-poor blood from the right ventricle to the lungs. Pulmonary veins = Carry oxygen-rich blood from the lungs to the left atrium. Aorta = Largest blood vessel in the body, carries oxygen-rich blood from the left ventricle to the body. Tricuspid valve = Separates the right atrium from the right ventricle. Bicuspid valve = Separates the left atrium from the left ventricle. Semilunar valves = Prevent backflow of blood and ensure one-way flow. Signup and view all the answers

What is the function of the septum in the heart?

The septum is a muscular wall that separates the left side and right side of the heart. Signup and view all the answers

Arteries carry oxygen-poor blood away from the heart.

False Signup and view all the answers

What is the function of the chordae tendinae?

Chordae tendinae are strong, fibrous strings that prevent valves from inverting when the heart contracts. Signup and view all the answers

Explain the difference in structure between arteries and veins.

Both arteries and veins have three cell layers, but arteries are thicker with elastic walls and a smaller opening, while veins have thinner walls and a larger opening. Signup and view all the answers

Describe the role of capillaries in the circulatory system.

Capillaries are the site of exchange between the blood and the cells of the body tissues. Signup and view all the answers

Which pathway of the circulatory system transports blood between the right side of the heart and the lungs?

Pulmonary pathway Signup and view all the answers

Which pathway of the circulatory system transports blood between the left side of the heart and the rest of the body?

Systemic pathway Signup and view all the answers

Which pathway of the circulatory system provides blood to the muscle tissue of the heart itself?

Coronary pathway Signup and view all the answers

What is the sinoatrial (SA) node, and what is its function?

The sinoatrial (SA) node is a bundle of specialized muscle tissue that generates an electrical signal to stimulate the atria to contract. It is often referred to as the pacemaker of the heart. Signup and view all the answers

Where is the atrioventricular (AV) node located, and what is its role in the heart beat?

The atrioventricular (AV) node is located between the atria and ventricles. It serves to delay the electrical signal coming from the atria, allowing time for the ventricles to fill with blood before contracting. Signup and view all the answers

What is the bundle of His?

The bundle of His is a bundle of specialized fibers that transmits the electrical signal from the AV node through the heart. Signup and view all the answers

What are Purkinje fibers?

Purkinje fibers are fast-conducting fibers that initiate the contraction of the ventricles. Signup and view all the answers

Which of the following events is NOT a part of the heart beat?

Blood is pumped to the lungs via the aorta. Signup and view all the answers

What is the function of the electrocardiogram (ECG)?

The electrocardiogram (ECG) records the electrical activity of the heart, providing valuable insights into its health and function. Signup and view all the answers

What is blood pressure, and what does it measure?

Blood pressure is the pressure exerted on the walls of blood vessels by blood as it passes through. It measures the force of blood pushing against the vessel walls. Signup and view all the answers

Study Notes

Circulatory and Immune Systems

Blood vessels in the human body would stretch to 100,000 km.
A blue whale's heart is about the size of a compact car and beats only 5 times per minute.
A shrew has a heart rate of approximately 1000 beats per minute.
Blood is never blue.

Main Functions of the Circulatory System

Transports gases, nutrients, hormones, and waste products throughout the body.
Regulates internal body temperature.
Protects against blood loss from injuries and disease-causing microbes and toxins.

Major Components of the Circulatory System

Heart: An organ that pumps blood throughout the body.
Blood vessels: Pathways for blood to travel.
Blood: Carries nutrients, gases, water, waste products, and other materials throughout the body.

Heart Structure

Cardiac muscle: Specialized myogenic muscle tissue, responsible for rhythmic contractions, controlled involuntarily.
Pericardium: Fibrous sac holding the heart in the chest cavity.

Heart Chambers and Pathways

Top Chambers (receiving): Right Atrium, Left Atrium
Bottom Chambers (pumping): Right Ventricle, Left Ventricle
Blood flow through the heart involves oxygenated and deoxygenated blood pathways.

Heart Valves

Tricuspid valve (Right AV valve): Separates the right atrium from the right ventricle, has three flaps.
Bicuspid valve (Left AV valve or Mitral Valve): Separates the left atrium from the left ventricle, has two flaps.
Semilunar valves: Consist of pulmonary semilunar valve and aortic semilunar valve which control blood flow out of the ventricles.
Chordae Tendineae: Strong fibrous strings preventing valve inversion during ventricular contraction. Controlled by papillary muscles in the ventricles.

Blood Vessels

Arteries: Carry blood away from the heart. Have thick walls with three cell layers, elastic walls for expansion/recoil (pulse), maintaining blood pressure. Arterioles are small branches connecting arteries to capillaries.
Capillaries: Networks for exchanging matter (oxygen, carbon dioxide, nutrients, waste) between blood and cells. They have thin walls (single cell layer).
Veins: Carry blood towards the heart. Have thinner walls than arteries, larger inner circumference and one-way valves preventing backflow. Venules connect veins to capillaries. Muscle contractions help veins push blood.

Pathways of the Circulatory System

Pulmonary pathway: Transports blood between the right side of the heart and the lungs.
Systemic pathway: Transports blood between the left side of the heart and the rest of the body.
Coronary pathway: Provides blood to the heart muscle itself.

The Heart Beat

Sinoatrial (SA) node ("pacemaker"): Specialized muscle tissue initiating electrical signals for atrial contraction.
Atrioventricular (AV) node: Delays the signal, allowing the atria to fully contract before ventricular contraction.
Bundle of His: Transmits signals through specialized fibers.
Purkinje fibers: Initiate ventricular contraction.

Order of Events: Heart Beat

Blood enters atria, SA node stimulates atrial contraction.
Bicuspid and tricuspid valves open, blood moves into the ventricles.
Purkinje fibers stimulate ventricular contraction.
Bicuspid & tricuspid valves close, semilunar valves open, blood leaves ventricles and semilunar valves close.

Electrocardiogram (ECG)

Records electrical activity of the heart. Measurements are small, measuring only a few milliVolts, corresponding to the "lub" and "dub" sounds.

Blood Pressure

Pressure exerted on vessel walls by blood as it moves; measured using a sphygmomanometer.
Systolic; maximum pressure during ventricular contraction (e.g., 120 mmHg).
Diastolic; lowest pressure before ventricular contraction (e.g., 80 mmHg).

Cardiac Output and Stroke Volume

Cardiac output: Amount of blood pumped by left ventricle per minute (average: 5,000 mL/min).
Stroke volume: Amount of blood forced out of left ventricle per heartbeat (average: 60-80 mL).
Heart rate: Number of heartbeats per minute (average: 60-100 bpm).
Cardiac Output=(Heart rate) x (Stroke volume)

Cardiovascular Fitness

A low resting heart rate indicates cardiovascular fitness. Regular cardiovascular exercise enlarges ventricular chambers, increases ventricular distensibility, and strengthens ventricle walls.

Blood Pressure and Velocity in the Vessels

Blood pressure and velocity in arteries, arterioles, capillaries, venules, and veins, related to total cross-sectional area of blood vessels.

Blood and Circulation - Components of Blood

Plasma (fluid portion): 55% (Water, Ions, Proteins, Nutrients, Waste, Gases).
Formed elements (solid): 45% (RBCs, WBCs, Platelets). All formed elements are produced in the bone marrow.

Red Blood Cells (Erythrocytes)

Make up about 44% of blood volume.
Life span is about 120 days.
Broken down in the liver and excreted as bile pigments.
Extra RBCs are stored in the spleen.
Mature red blood cell is enucleated to hold more hemoglobin.
Hemoglobin is an iron-containing protein that binds oxygen.

Anemia

Insufficient RBCs or hemoglobin.
Hypoxic (low oxygen) environments like high altitudes or low oxygen levels prolong the production of more red blood cells.

White Blood Cells (Leukocytes)

Less than 1% of blood volume (but may increase).
Life span 5-20 days.
Leukocytes are the body's cells defending against infections and foreign materials.

Platelets (Thrombocytes)

Fragments of larger cells in bone marrow, fraction of 1% of blood volume.
No nucleus and live about 2-8 days.
Function in blood clotting.

Blood Functions

Transports hormones, nutrients, vitamins, minerals, and gases through the body.
Transports waste from cells to be excreted from the body.

Blood Clotting

Substances released by broken blood vessels attract platelets to the site of injury.
A cascade of enzyme-catalyzed reactions involving thrombin and fibrin create a mesh-like clot to trap blood cells.

Homeostatic Regulation

Vasodilation: Blood vessels dilate near the skin to release heat to the air when the internal body temperature is too high.
Vasoconstriction: Blood vessels constrict near the skin to retain heat when the external body temperature is too low.
Sweating cools the body.
Dehydration is a problem, especially when body temperature is too high because of the excess sweating.
Body generates heat through shivering when external temperature is very low.
Countercurrent heat exchange mechanism: Blood vessels in the arm exchange heat to help warm the blood in veins carrying blood back towards the core, and/or cool down blood flowing to the extremities.

Circulation and the Action of Capillaries

Capillaries are sites where material are exchanged between the blood and body tissues.
Wastes and carbon dioxide leave the body cells to enter the bloodstream.
Nutrients, oxygen, and water leave the bloodstream to enter body cells.
Blood flow through capillaries can be controlled through the action of sphincters.
Capillaries are the only blood vessels thin enough for diffusion.

Lymph and Lymphatic System

Lymph is similar to interstitial fluid.
Lymph forms in closed-ended tubes in capillary beds, distinct from continuous blood flow between the heart and capillaries.
Lymph vessels have valves ensuring one-way flow, like veins.
Lymphatic system helps maintain a fluid balance in the body.
The lymphatic system absorbs interstitial fluid and carries it to ducts emptying near the heart.
The lymphatic system transports digested fats from the small intestine into the bloodstream.
Lymphatic system contains glands and nodes.
The lymph nodes contain immune cells, macrophages, to trap and destroy circulating bacteria within the body.

Defence System - Immune System

Microbes (bacteria, fungi, protists, viruses) are found in the air, food, and water.
Pathogens can be dangerous to humans.
The immune system of the human body helps prevent pathogens from entering the body and destroys foreign pathogens that do enter.

First Line of Defence

Physical and chemical barriers to prevent pathogen entry.
Eyelashes prevent pathogens entering the eye.
Cilia in the respiratory tract move debris out.
Tears wash away foreign particles and contain lysozyme.
Stomach acid (HCl) has a low pH to kill microorganisms.
Mucus traps foreign particles in the respiratory tract.
Nose hairs trap foreign particles preventing entry in the respiratory tract.
Skin; physical and chemical barrier -Perspiration (sweat) contains acid to kill bacteria,- Skin oils are antimicrobial, - Keratin protein hardens the outer layer, preventing the penetration of pathogens.
Vomiting and diarrhea expel pathogens from the digestive tract.

Second Line of Defence - Cell-mediated Immunity

Inflammation: Non-phagocytic leukocytes (white blood cells) release histamines. Histamines cause blood vessels to dilate and become more permeable; this results in redness, swelling, and pain.
Fever: Certain leukocytes release chemicals to increase body temperature, slowing bacterial growth.
Macrophages: White blood cells that ingest and destroy bacteria using phagocytosis. They are non-specific and engulf foreign bodies. Pus is dead macrophages and bacteria. After destroying pathogens, macrophages present the pathogen's antigens on their surfaces.

Third Line of Defense - Specific Antibody-Mediated Immunity

Antigens: Marker molecules found on pathogens. Toxins and substances produced by bacteria can also act as antigens.
Lymphocytes: White blood cells involved in immune response, divided into T and B cells.
T-Cells mature in the thymus. Helper T-cells recognize antigens from macrophages; they release chemicals that stimulate T cells to divide and activate more macrophages and help B-cells; Killer T cells destroy infected cells by puncturing holes in their membranes; Suppressor T cells suppress the immune response after clearing the infection; Memory T cells are a form of a long-term immune response to help the body act quicker if the pathogen is encountered again.
B Cells mature in bone marrow. Antigen receptors on B cells activate the B cell when it encounters the corresponding antigen, resulting in the creation of plasma cells and memory cells by dividing. Plasma cells release enormous numbers of antibodies into the bloodstream, complimentary to the antigen. Antibodies coat the pathogens, neutralizing them, and making them easier for the macrophages to engulf and destroy. After this stage, memory B cells remain to create a second response if the pathogen enters the body again.
The body recognizes the antigens to distinguish itself from the pathogens.

Blood Types

ABO System: Blood types are inherited where each parent has two alleles for blood type, and the resulting blood type is determined by which alleles were passed from each parent. (A, B, O).
Blood type Compatibility: Blood types have compatible antigens and antibodies that do not cause clumping. For example, a person with blood type A can safely receive from blood type A or O. However, a person with blood type A cannot safely receive from blood type B or AB,. If incompatible blood types are mixed, the process of agglutination occurs where the red blood cells clump; this blocks circulation.
Rh system: The Rh factor is an additional group of antigens found on red blood cells.
Rh positive (Rh+): Individuals with Rh antigens do not produce anti-Rh antibodies.
Rh negative (Rh-): Individuals without Rh antigens can produce anti-Rh antibodies if they come into contact with Rh+ blood (for example, through a transfusion).
Hemolytic Disease of Newborns (HDN): In the instance where the mother is Rh- and the fetus is Rh+, the mother can develop antibodies that will cross the placenta damaging the fetus's red blood cells. This is a potential complication in the mother's subsequent pregnancies. An injection given to the mother at the time of delivery or earlier can prevent the mother from developing anti-Rh antibodies.

Immunity

Active immunity: Acquired by producing antibodies in response to pathogen exposure. Active immunity can develop from exposure to the pathogen or vaccinations where a weakened or dead pathogen is introduced to stimulate an antibody response.
Passive immunity: Acquired by receiving antibodies from another person or animal; does not last as long as active immunity; antibodies can cross the placenta or are present in breast milk for short term protection.

Immune Response Summary

The immune response has three lines of defense; this includes recognition of the pathogens (or antigens), followed by an immune response using white blood cells and chemicals to help destroy the pathogen or foreign organism, and finally a reminder immune response for long term memory of the pathogen so a quicker response can be triggered if the pathogen enters again.

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