Chapter 8 Notes

Chapter Concepts 8.1 Structures of the Circulatory System

• The heart and blood vessels form the cardiovascular system.
• The mammalian heart has four chambers and acts as a double pump.
• Three circulatory pathways: pulmonary, systemic, and coronary.

8.2 Blood and Circulation

• Blood is plasma, red blood cells, white blood cells, and platelets.
• Blood transports materials and regulates temperature for homeostasis.

8.3 The Lymphatic System and Immunity

• The lymphatic system is tied to blood vessels in the cardiovascular system.
• It maintains fluid balance and is part of the immune system.
• The body's defense system includes non-specific and specific (immunity) defenses.
• The specific immune system has cells that recognize and neutralize foreign substances.

Watching Blood Flow (Launch Lab)

• Observing blood flow in a goldfish tail.
• Analysis Questions:
  • Possible functions of blood flowing through tiny vessels.
  • Reasons for small vessel size; why not one large vessel?
  • Factors that could speed up or slow down blood movement.
  • Substances in the observed vessels.
  • What's responsible for blood movement; is it universal?
  • Blood direction; hypothesis to explain observations.
• Transportation network analogy: comparing a city to the circulatory system.

Main Functions of the Circulatory System

• Single-celled organisms use diffusion, active transport, and cytoplasmic streaming (requires ATP) for matter exchange.
• Multicellular organisms (like humans) require an efficient transport system.
• Three Main Functions:
  • Transports gases (respiratory system), nutrients (digestive system), and wastes (excretory system).
  • Regulates internal temperature and transports hormones (endocrine system).
  • Protects against blood loss (platelets) and disease-causing microbes (white blood cells).

Major Components of the Circulatory System

• Three components: the heart, blood vessels, and blood.
• The heart pumps blood.
• Blood vessels are the “roadways”.
• Blood carries materials.
• Cardiovascular system = heart + blood vessels.

Structures of the Circulatory System (Section 8.1)

• Section Outcomes: Identify structures.
  • Describe blood vessel structure/function.
  • Describe heart action and blood circulation.
  • Dissect a mammalian heart.
  • Design an investigation to examine heart rate & blood pressure.
  • Identify circulatory system disorders and treatments.
  • Investigate relationship between blood pressure, heart rate & exercise.
• Key Terms: circulatory system, atria, ventricles, septum, vena cavae, pulmonary arteries/veins, aorta, valves, arteries, veins, capillaries, sinoatrial (SA) node, atrioventricular (AV) node, blood pressure, systolic/diastolic pressure, pulmonary/systemic/coronary pathways.

The Structure of the Heart

• Heart size: fist squeezed.
• Force: squeezing a tennis ball.
• Energy usage over 50 years: raises a battleship.
• Location: slightly left of chest's middle.
• Functions: pumping, separating oxygen-rich/poor blood, ensuring one-way flow.
• Cardiac muscle: unique, rhythmical, involuntary, fatigue-resistant.
• Four chambers (mammals and birds): atria (top), ventricles (bottom), separated by the septum (muscular wall).
  • Atria fill with blood (from the body or lungs).
  • Ventricles pump blood (to the body or lungs).
• Right side: receives blood from body tissues, pumps to lungs.
  • Vena cavae (superior/inferior) open into the right atrium.
  • Superior vena cava: head, chest, arms.
  • Inferior vena cava: from elsewhere.
  • Blood flows to the right ventricle, then the pulmonary trunk, then the left and right pulmonary arteries (oxygen-poor blood).
• Left side: receives oxygen-rich blood from lungs, pumps to the body.
  • Pulmonary veins carry blood to the left atrium (oxygenated blood).
  • The left atrium pumps blood to the left ventricle, where it's pumped through the aorta.
• Four valves ensure correct blood direction: atrioventricular and semilunar.
  • Atrioventricular valves:
    • Tricuspid valve (right side): three flaps.
    • Bicuspid valve (left side): two flaps.
  • Semilunar valves.

The Structure of the Blood Vessels

• Three types: arteries, veins, capillaries.
• Arteries: oxygen-rich blood away from the heart.
• Veins: oxygen-poor blood towards the heart.
• Capillaries: network joining arteries and veins; material exchange happens here.
• Arteries have elastic walls: expands during ventricular contraction and snaps back during relaxation, aiding blood flow.
• Measuring pulse: rhythmic expansion/contraction of artery.
• Veins have thinner walls, larger circumference, are less elastic.
• Muscle contraction aids blood flow in veins; one-way valves prevent backflow (especially in legs, against gravity).
• Capillaries: smallest blood vessels, single-cell wall, ~8 µm diameter (blood cells pass single file).

The Beating Heart

• Electrical signal triggers heartbeat (rate/strength controlled by nervous system).
• Sinoatrial (SA) node (pacemaker): muscle tissue bundle stimulates rhythmical contraction/relaxation.
• SA node in the right atrium wall sends an electrical signal over atria (simultaneous contraction).
• Atrioventricular (AV) node: receives signal from SA node, transmits it through bundle of His.
• Bundle of His relays signal via bundle branches into fast-conducting Purkinje fibers (almost simultaneous contraction of ventricles).
• Electrocardiogram (ECG): measures voltage change from electrical signal.
  • P wave: atrial contraction.
  • QRS spike: ventricular contraction.
  • T spike: ventricular recovery.
  • Changes indicate heart conditions.

Blood Pressure

• Blood pressure: force against vessel walls.
• Changes with heartbeat phases.
• Systolic pressure: maximum pressure during ventricular contraction.
• Diastolic pressure: lowest pressure before ventricular contraction.
• Measured in mmHg using a sphygmomanometer.
• Normal BP: below 120 \over 80 mmHg.
• Arterial pressure never drops to zero, ensuring continuous blood flow.

Cardiac Output and Stroke Volume

• Cardiac output: Amount of blood pumped by the heart, measured in mL/min.
• Cardiac output = Heart rate × Stroke volume.
• Stroke volume: blood amount forced out per heartbeat.
• Average person stroke volume: 70 mL.
• Resting heart rate: ~70 beats/min.
• Cardiac Output: ~4900 mL/min.
• Blood volume: ~5L circulates entirely every minute.

Cardiovascular Fitness

• Low resting heart rate signifies cardiovascular fitness.
• Maximum heart rate: highest rate during physical effort (decreases with age).
• Recovery time: time for heart to return to resting rate after effort (decreases with fitness).
• Cardiovascular exercise increases resting stroke volume.
• Strength training (weight lifting): increases wall thickness, potentially limiting stroke volume.

Pathways of the Circulatory System

• Blood vessels in three pathways: pulmonary, systemic, and coronary.
• Pulmonary pathway: transports oxygen-poor blood to lungs for gas exchange; oxygen-rich blood returns to the left heart.
• Systemic pathway: moves oxygen-rich blood from the left ventricle to body tissues; oxygen/nutrients move in; waste products move out.
• Coronary pathway: provides blood to the heart muscle tissue itself.

Tracing Blood Flow through the Pulmonary and Systemic Pathways

• Continuous cycle.
• Oxygen-poor blood flows via Vena Cavae into Right Atrium. Contraction pumps blood into Right Ventricle.
• Ventricle contracts, pumping blood into Pulmonary Trunk, then into Left and Right Pulmonary Arteries.
• Pulmonary Arteries lead to lung capillaries for gas exchange.
• Oxygen-enriched blood continues via Pulmonary Veins to reach Left Atrium of the heart.
• Atrial contraction sends blood to Left Ventricle.
• Left Ventricle pumps blood through Aorta.
• Aorta divides into arteries going to tissues.

Tracing Blood Flow through the Coronary Pathway

• Heart needs an external pathway to receive blood because its thick walls and oxygen in blood cannot diffuse effectively.
• Coronary Pathway provides energy & matter to muscle cells via capillaries imbedded in the heart wall. Vessels split of Aorta just as it exists the ventricle and become smaller. Vessels encircle the heart (corona).
• Oxygen-rich blood goes through these vessels to be used for gas exchange. Oxygen-poor blood is flown out of the arteries to coronary veins and joins together to renter the Right Ventricle and flows to the lungs for oxygen.

Cardiovascular Disorders and Treatments

• Cardiovascular disease: leading cause of death; risk factors include smoking, obesity, lack of exercise.
• Arteriosclerosis: artery walls thicken/harden; atherosclerosis (plaque buildup).
• Plaque decreases blood flow, increasing blood pressure; can lead to angina, clots, shortness of breath, heart attack, or heart failure.
• Lifestyle choices (exercise, no smoking, diet) reduce risk.
• Treatment options: Aspirin (prevents clots), clot-busters (urokinase, t-PA). Surgical options are angioplasty and coronary bypass.
  • Angioplasty: Tube forces artery open; vascular stent holds vessel open.
  • Coronary bypass: Healthy vessel segment bypasses blocked vessel.
• Congenital heart defects: present since birth (wall, valve, or vessel problems near the heart).
• Heart murmur: blood misflow in the heart; valve defects heard with a stethoscope.
• Digitizing technology creates models from CT/CAT/MRI scans for surgical planning.
• Transplants.

Blood and Circulation (Section 8.2)

• Blood links cells/organs; classified as connective tissue. Composition: fluid (plasma) and solid portion.
• Plasma ~55% blood volume: Water plus dissolved gases, proteins, sugars, vitamins, minerals, hormones, and waste products.