Circulation and Respiration Chapter 24 Quiz

Introduction to Circulation and Respiration

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Chapter 24 Outline

• Circulation and Respiration
• Essentials of the Living World, Seventh Edition
• Authors: George Johnson, Joel Bergh

24.1 Open and Closed Circulatory Systems

• Unicellular protists obtain oxygen and nutrients through simple diffusion.
• Cnidarians and flatworms have cells that are directly exposed to the external environment or a gastrovascular cavity.
• Large animals have tissues several cell layers thick, making surface exchange inefficient.
• Oxygen and nutrients are transported from the environment/digestive cavity to body cells via an internal circulatory system.
• Two main types of circulatory systems exist: open and closed.

24.1 Open Circulatory Systems

• No distinction between circulating fluid (blood) and extracellular fluid (body tissues).
• This fluid is called hemolymph.
• Insects have a muscular tube (heart) that pumps hemolymph through a network of open-ended channels.

24.1 Closed Circulatory Systems

• Circulating fluid (blood) is always enclosed within blood vessels.
• Annelids (like earthworms) and vertebrates have closed circulatory systems.
• Blood travels away from the heart through arteries.
• Exchange of gases and nutrients occurs through thin-walled capillaries.
• Blood returns to the heart through veins.

Figure 24.1: Circulatory Systems in the Animal Kingdom

• Illustrates three types of circulatory systems found in animals.
• Shows examples of gastrovascular cavity (planaria), open circulation (insect), and closed circulation (earthworm).

24.1 Function of the Circulatory System

• Transportation: Gases, nutrients, wastes, and hormones are transported.
• Regulation: Cardiovascular system regulates body temperature; vertebrates use countercurrent heat exchange to regulate body temperature in cold environments.
• Protection: System protects against injury and foreign microbes or toxins.

Figure 24.2: Countercurrent Heat Exchange

• Illustrates countercurrent heat exchange in an animal as a mechanism for regulating body temperature.
• Warm blood in the arteries warms the cold blood in the veins within a capillary bed.

24.2 Architecture of the Vertebrate Circulatory System

• The system comprises three elements: heart, blood vessels, blood.
• The heart is a muscular pump that pushes blood throughout the body.
• Blood vessels are a network of tubes through which blood moves.
• Blood is the fluid that circulates through the vessels.

24.2 Blood Flow in Vertebrate Systems

• Blood leaves the heart via arteries.
• Blood moves into smaller arterioles.
• Tiny capillaries connect arterioles to venules (small veins).
• Venules and then veins carry blood back to the heart.

Figure 24.3: Blood Flow in the Circulatory System

• Illustrates the flow of blood, starting with arteries, moving through smaller arterioles and capillaries and back to the heart via venules, and then veins.

24.2 Capillary Structure

• Capillaries have the largest total cross-sectional area of any other blood vessel type.
• Capillary beds can open or close based on tissue physiological needs.

Figure 24.4: Capillary Network

• The network connects arteries with veins.
• Precapillary sphincters regulate blood flow through capillary beds.

24.2 Artery Structure

• Arteries are more than simple pipes.
• They need to expand with the pressure caused by heart contractions.
• Arterial walls contain several layers, including endothelial cells, elastic fibers, and smooth muscle surrounded by connective tissue.

Figure 24.5a: Artery Structure

• Illustrates the layered structure of an artery, highlighting the different tissue layers.

24.2 Capillary Function

• Capillaries are the site of material exchange between the blood and body cells.
• Capillaries are narrow and have thin walls to facilitate exchange.
• Almost all cells in the vertebrate body are within 100 micrometers of a capillary.

Figure 24.5b: Capillary Structure

• Illustrates the structure of a capillary.

24.2 Vein Function

• Veins return blood to the heart.
• Vein walls are thinner due to lower blood pressure as compared to arteries.
• Veins have unidirectional valves to prevent backflow.

Figure 24.5c: Vein Structure

• Shows the structure of blood vessels in detail, emphasizing the layers in a vein.

24.2 Blood Plasma

• Blood plasma is a complex water solution of various dissolved substances.
• Metabolites and wastes (e.g., glucose, vitamins, hormones) are dissolved in the plasma.
• Salts and ions (e.g., sodium, chloride, bicarbonate) are dissolved in the plasma.
• Proteins help maintain water balance in the plasma.
• Serum albumin maintains osmotic balance; other proteins include antibodies, globulins, and fibrinogen (involved in blood clotting).

Figure 24.9: Fibrin Threads

• Illustrates the presence of fibrin, a protein crucial for blood clotting.

24.3 Blood Cells

• Red blood cells, white blood cells, and platelets comprise the cellular components of blood.
• Hematocrit is the fraction of blood volume occupied by red blood cells (generally ~45% in humans).
• Red blood cells resemble flat disks.
• The interior is packed with hemoglobin for oxygen transport.

24.3 Red blood Cells

• Red blood cells are short-lived and replaced in the bone marrow.

24.3 White Blood Cells

• They are colorless and contain no hemoglobin; diverse cells responsible for the immune system.

24.3 Platelets

• Platelets are cell fragments from megakaryocytes (large cells in the bone marrow) crucial for blood clotting.

Figure 24.10: Types of Blood Cells

• Chart exhibiting different types of blood cells, their life spans, and functions.

24.4 Human Circulatory System

• Humans and other mammals have a four-chambered heart with two complete pumping circuits.
• One side pumps blood to the lungs to pick up oxygen; other side distributes oxygenated blood to the body.

24.4 Left Ventricle Function

• Oxygen-rich blood returns from the lungs via pulmonary veins to the left atrium.
• Blood flows passively to the left ventricle via the bicuspid (mitral) valve.

24.4 Aorta

• The thick-walled left ventricle contracts, sending oxygenated blood through the large artery called the aorta, distributing outwards into the body.

24.4 Right Ventricle Function

• Blood travels through the body via vena cavae, then to the right atrium.
• Blood moves from right atrium through the tricuspid valve to the right ventricle.
• Right ventricle contracts, pushing blood through the pulmonary valve to pulmonary arteries (leading to the lungs).

Figure 24.11: The Heart and Circulation in Humans

• Shows the human heart's anatomy, including blood flow through the chambers and major vessels.

24.4 Heartbeat Monitoring

• Listening with a stethoscope: "Lub" (bikuspid and tricuspid valves closing -start of ventricular contraction); "Dub" (pulmonary and aortic valves closing- end of ventricular contraction).
• Heart murmurs indicate valve dysfunction.

24.4 Blood Pressure Monitoring

• Measurements made using a sphygmomanometer on the brachial artery.
• Systolic pressure (high) is recorded during ventricular contraction; diastolic pressure (low) is recorded during atrial filling.

Figure 24.12: Measuring Blood Pressure

• Diagram illustrates how blood pressure is measured using a sphygmomanometer and a stethoscope.

24.4 Heart Contraction

• Heart contraction involves coordinated muscular contractions (atria followed by ventricles).
• Sinoatrial (SA) node (pacemaker) initiates each heartbeat in the right atrium wall.

24.4 Heart Signal Transmission

• The signal from SA node delays for 0.1 sec through the atrioventricular (AV) node before reaching ventricles for contraction.

24.4 Electrical Conduction of the Ventricles

• Signal travels through the Bundle of His.
• Signal is then transferred to Purkinje fibers generating almost simultaneous contraction across the ventricles.
• Electrocardiogram (ECG or EKG) captures electrical activity of the heart.

Figure 24.13: Mammalian Heart Contraction

• Illustration showing steps in mammalian heart contraction, indicating the sequence of events.

24.5 Respiratory Systems

• Respiration is the uptake of oxygen and release of carbon dioxide.
• Most primitive animal phyla obtain oxygen directly from the environment by diffusion.
• More advanced phyla possess specific respiratory organs (e.g., gills, tracheae, lungs).

Figure 24.14: Gas Exchange in Animals

• Diagram illustrating organisms using gills (fish), tracheae (insects), or lungs (mammals) for gas exchange.

24.6 Human Respiratory System: Introduction

• Lungs are adaptations for terrestrial habitat in mammals.
• A pair of lungs lies within the thoracic cavity.

24.6 Human Respiratory System: Airflow

• Air flows through nasal cavity, pharynx, larynx (voice box), trachea (windpipe).
• Air travels through bronchi (in lungs), then to bronchioles.
• Bronchioles lead to alveoli where gas exchange occurs.

Figure 24.15: Human Respiratory System

• Diagram showing anatomy of the human respiratory system, from external structures like the nasal cavity to internal structures like alveoli.

24.6 Human Respiratory System: Mechanisms

• Diaphragm separates thoracic cavity from abdominal cavity.
• Lungs are covered by pleural membranes.
• Pleural membranes adhere to thoracic cavity to couple lungs to the thoracic walls.
• Air drawn into lungs by negative pressure.

24.6 Human Respiratory System: Breathing

• Inhalation: Muscular contractions expanding the chest cavity and diaphragm creating lower pressure in lungs causing air flow inward.
• Exhalation: Ribs and diaphragm return to their resting positions, increasing lung pressure and expelling air.

24.7 How Respiration Works - Gas Exchange

• Oxygen carried in blood by hemoglobin.
• Hemoglobin contains iron enabling reversible binding to oxygen.

Figure 24.16: Hemoglobin Molecule

• Shows hemoglobin's structure and how oxygen binds.

24.7 Hemoglobin and Oxygen Transport

• High oxygen levels at the lung cause hemoglobin molecules to carry a full load of O2.
• Low oxygen levels in tissues cause hemoglobin to release oxygen.
• CO2 presence in hemoglobin alters shape aiding oxygen release.

24.7 Carbon Dioxide Transport

• CO2 is transported by blood in various ways; about 8% dissolves in the plasma.
• 20% binds to hemoglobin (different site than oxygen).
• Remaining 72% diffuses into red blood cells to maintain gradient enabling CO2 exit the tissues and into the plasma.