The Circulatory and Respiratory Systems

The Circulatory and Respiratory Systems Chapter 37 A beginning Circulatory System-Functions • Helps maintain homeostasis by controlling the surround...
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The Circulatory and Respiratory Systems Chapter 37 A beginning

Circulatory System-Functions • Helps maintain homeostasis by controlling the surroundings of cells • Heart: heart and body circulation, heartbeat • Vessels:Individual organ and cells supply and exchange of materials

The Heart • Pericardium: protective sac around the heart • Myocardium: the actual heart muscle, non striated cardiac muscle, does not fatigue

Heart Anatomy

Heart Anatomy • Atria: thin walled, collection for blood returning to heart • Ventricles: thick, powerful walls, pump blood to organs • Septum: thick wall between the ventricles

Heart Anatomy • Valves: Prevent backflow of blood into the chambers • Nodes: act as both muscle and nervous tissue, control heartbeat –Pacemaker: Sinoatrial Node

Circulation Through Body

Circulation Through Body • Pulmonary Circulation: Flow of blood from the right side of the heart to the lungs and back • Systemic Circulation: Flow of blood from the left side of the heart to the body and back

Blood Flow Through the Heart • Stage 1: Blood returning from the body in the Vena Cava enters the Right Atrium, carrying CO2, At the same time O2 rich Blood returning from lungs enters Left Atrium from Pulmonary Vein

Blood Flow Through the Heart • Stage 2: The Atrioventricular Node forces the Atrias to contract, Blood passes by the Atrioventricular valves and empties into the Ventricles

Blood Flow Through the Heart • Stage 3: AV valves close, Sinoatrial Node sends signal for ventricles to contract

Blood Flow Through the Heart • Stage 4: The Semilunar valves open as the ventricles contract. The blood from the Right Ventricle is pushed into the Pulmonary Artery (Pulmonary Circuit) to lungs for gas exchange

Blood Flow Through the Heart • Stage 4: The blood from the Left Ventricle is forced out the Aorta to deliver O2 to the systemic circuit

The Blood Vessels • As blood flows through the circulatory system, it moves through three types of blood vessels: Arteries, Capillaries, and Veins

Arteries • Large, carry blood from heart, have thick walls made up of three layers to handle high pressure

Capillaries • Smallest of the blood vessels, one cell layer thick for exchange of chemicals with fluids

Veins • Thin walled, return blood to heart, blood is moved by muscle contraction and valves to prevent backflow (because is going against gravity)

Blood Pressure • When the heart contracts it produces a hydrostatic force against a vessel wall, called blood pressure • Higher in Arteries, keeps blood flowing

Blood Pressure • Systolic Pressure: the force in the arteries when the ventricles contract • Diastolic Pressure: the force in the arteries when the ventricles relax


Blood • Connective tissue with cells suspended in plasma • Contains: Plasma (Electrolytes, plasma proteins), Erythrocytes (RBC’s), Leukocytes (WBC’s), and Platelets

Plasma • 90% water • Electrolytes: inorganic salts, maintain osmosis, controlled by kidneys • Plasma Proteins: help buffer blood • Also: nutrients, metabolic wastes, respiratory gases, hormones

Erythrocytes • Also called Red Blood Cell’s • Most numerous cells, 5x106 in a ml of blood • Transport O2, shaped like discs • Contain Hemoglobin, which uses Iron to bind to 02

Erythrocytes • Produced in Bone Marrow • Lack Nuclei • Disc shape allows them to be flexible in small capillaries

Leukocytes • Also called White Blood Cells • Produced in Red Marrow, contain Nuclei • Function is to protect, they attack foreign substances or organisms

Leukocytes • Number of cells is increased during infection • Some engulf cells (Phagocytes), others secrete chemicals (Basophils)

Platelets • Lack nuclei • Function in blood clotting • Are fragments of large cells in bone marrow • Sticky structure allows them to adhere, and help stop flow of blood

Inactive Platelets

Active Platelets

The Lymphatic System • Returns fluid (called Lymph) to the blood that leaks out of the vessel walls and aids in body defense, help absorb fat in small intestine • Lymph Nodes: specialized swellings that filter, and attack viruses and bacteria

The Respiratory System

The Respiratory System • A breath of fresh air……

• Respiration: the process in which O2 and CO2 are exchanged between cells, the blood, and air in the lungs • Consists of: Nose, Pharynx, Larynx, Trachea, Bronchi, and Lungs

Anatomy of Respiration (Figure on page 957) • Pharynx: passage way for air/food at the back of the throat • Larynx: contain vocal cords • Trachea: connects Pharynx to the Bronchi, called the windpipe, protected by epiglottis

Anatomy of Respiration • Bronchi: large passageways in chest cavity, each leads to a lung, divide in smaller bronchioles • Alveoli: tiny air sacs, smallest vesicle in lungs, grouped in clusters, surrounded by thin-walled capillaries, increase surface area for gas exchange

Gas Exchange • Occurs in Alveoli, O2 dissolves in surfactant, and diffuses across the cell membrane, CO2 in capillaries diffuses into the lungs • Efficient: removes 30% of O2 in every breath

Breathing • Controlled by Medulla Oblongata in brain • Movement of Air in and out of lungs, controlled by the diaphragm

Breathing • When the diaphragm contracts, pulls the chest cavity and expands it, the negative pressure created forces air into the lungs, filling the passageways

Breathing • When the diaphragm relaxes, the pressure in lungs is greater, so air is pushed out, a passive event, can be increased using muscles around the chest cavity

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