Circulatory and Respiratory Systems

Describe the structure and function of the human heart. Trace the flow of blood through the heart and body. Distinguish between arteries, veins, and capillaries in terms of their structure and function. Distinguish between pulmonary circulation and systemic circulation. Summarize the functions of the lymphatic system.

The heart is the central organ of the cardiovascular system. Using this diagram, label the diagram of the heart in your notes

The valves are flaps of tissue that control the flow of the fluid The atrioventricular valves prevent blood from flowing backward into the atria

The valves are flaps of tissue that control the flow of the fluid The semilunar valves prevent blood from flowing back into the ventricles when the heart relaxes

1) Deoxygenated blood enters the right atrium 2) The right atrium sends deoxygenated blood into the right ventricle 3) The muscles of the right ventricle contract and force blood into the pulmonary arteries The pulmonary artery sends blood to the lungs. In the lungs, carbon dioxide diffuses out of the blood, and oxygen diffuses into the blood

4 4) When the blood leaves the lungs, it is full of oxygen and re-enters the heart in the left atrium ) The blood is pumped from the left atrium to the left ventricle 6) The blood is finally pumped from the left ventricle to the aorta and out to the body

The heart contracts its muscle cells in waves The sinoatrial (SA) node is a group of specialized heart-muscle cells that lies in the right atrium and regulates the contraction of the heart The atrioventricular (AV) node is a group of specialized heart-muscle cells that is located between the right atrium and right ventricle and generates electrical impulses that cause the ventricles of the heart to contract

A heartbeat has two phases Phase one is called systole and occurs when the ventricles contract Phase two is called diastole and occurs when the ventricles relax A series of pressure waves are caused by the contractions of the left ventricle when it forces blood through the arteries. This is called a pulse

The circulatory system is known as a closed system because the blood is contained within either the heart or the blood vessels at all times

The large, muscular vessels that carry blood away from the heart and to the body are called arteries From the artery, a series of smaller vessels called arterioles carry the blood to capillaries

The capillaries are a vast network of tiny vessels that allow an exchange between the blood and the cells to occur

After cells interact with the blood, the blood goes back to the heart. To do this, capillaries merge to form venules These venules are connected to a vein. A vein is a bundle of vascular tissue that transports fluids and nutrients back to the heart

The heart and blood vessels work together to form a continuous, closed system of circulation. This system contains two subsystems: the pulmonary circulation and the systemic circulation.

Section 3 – Respiratory System

 Differentiate external respiration from internal respiration.  Trace the path of air from the atmosphere to the bloodstream.  Describe how gases are exchanged in the lungs and transported in the bloodstream.  Summarize the skeletal and muscular changes that occur during breathing.  Describe how the rate of breathing is controlled.

 The function of the respiratory system is to exchange gases with the cardiovascular system.  The respiratory system involves both external respiration and internal respiration. External respiration is the exchange of gases between the atmosphere and the blood. Internal respiration is the exchange of gases between the blood and the cells of the body.

 The lungs are the central organs of the respiratory system in which gases are exchanged.  The lungs are located inside the thoracic cavity, which is bound by the rib cage and the diaphragm.

 The Path of Air External respiration begins at the mouth and at the nose. Air is filtered and moistened by various parts of the nose and mouth and then moves into the throat.

 The Path of Air, continued Air then moves from the pharynx through the epiglottis into a cartilaginous tube, called the trachea.  The epiglottis is a flap of cartilage that hangs at the entrance of the larynx and directs food and air to the correct places.

 The Path of Air, continued At the end of the trachea, the air moves into the two bronchi. The air moves through the bronchi and then into the smaller tubes called the bronchioles that branch from the bronchi.

 The Path of Air, continued Air finally makes its way through the bronchioles to the place where gas exchange takes place—alveoli. Gas exchange is facilitated by the enormous amount of surface area in the lungs.

 Gas Exchange in the Lungs When air enters the lungs, the oxygen in the air crosses the capillary walls and dissolves into the blood by diffusion. Carbon dioxide moves in the opposite direction, also by diffusion, and crosses the capillary walls to enter the alveoli.

 Transport of Oxygen Most of the oxygen absorbed into the blood combines with hemoglobin, which distributes the blood to cells.

 Transport of Carbon Dioxide Carbon dioxide diffuses into the blood and either stays in the plasma, binds to hemoglobin, or reacts with water to produce bicarbonate ions.

 Breathing is the process of moving air into and out of the lungs.  Inspiration is the process of taking air into the lungs.  When a deep breath is taken, the chest and ribs expand with help from the diaphragm

 Expiration is the process of releasing air from the lungs. When this happens, the diaphragm and rib muscles relax, which forces the lungs to deflate.

 Regulation of Breathing Both rate and depth of breathing change in order to provide oxygen and eliminate carbon dioxide from cells. The rate of breathing is controlled by the brain and brain stem by monitoring the concentration of carbon dioxide in the blood. All the activities used to regulate breathing are controlled subconsciously by the brain.