Topic+5+Human+Health+and+Physio+HD

=__Transport System__= = =
 * 5.2.1 Draw a diagram of the heart showing all four chambers, associated blood vessels and valves.**
 * All blood vessels connected directly to the heart, including coronary vessels, should be shown. Care should be taken to show relative wall thickness of the four chambers. The histology of the heart is not required.
 * http://www.nlm.nih.gov/medlineplus/ency/images/ency/fullsize/19612.jpg
 * http://www.nlm.nih.gov/medlineplus/ency/images/ency/fullsize/19612.jpg

__Heart Lab Investigations__
http://images.google.com/imgres?imgurl=http://www.abacon.com/plowman/images/fig42.gif&imgrefurl=http://www.abacon.com/dia/exphys/one.html&h=475&w=518&sz=42&hl=en&start=1&sig2=STd2Wohb8B33Cc8hlAntQQ&tbnid=N0fORfD9jPCEDM:&tbnh=120&tbnw=131&ei=c3PoRuLGJYnEiwHN2YSBBQ&prev=/images%3Fq%3DBlood%2BFlow%2Bthrough%2Bthe%2Bheart%26gbv%3D2%26svnum%3D10%26hl%3Den%26client%3Dfirefox-a%26channel%3Ds%26rls%3Dorg.mozilla:en-US:official%26sa%3DG
 * Blood Flow through the Heart

//A basic understanding is required, limited to the collection of blood by the atria which is then pumped out by the ventricles into the arteries. The direction of flow is controlled by atrio-ventricular and semilunar valves.//
 * 5.2.2 Describe the action of the heart in terms of collecting blood, pumping blood and opening and closing valves.**


 * 1.** Blood flows into the atria from the veins.
 * Deoxygenated blood from superior and inferior venae cavae -> right atrium
 * Oxygenated blood from pulmonary vein -> left atrium
 * 2.** The atria contract, forcing the atrio-ventricular valves to open.
 * 3**. Blood is forced through the open valves into the ventricles.
 * Right atrium -> atrio-ventricular valve -> right ventricle
 * Left atrium -> atrio-ventricular valve -> left ventricle
 * 4.** The semilunar valves are closed, so the ventricles are able to fill with blood.
 * 5.** The walls of the ventricles contract powerfully, increasing the pressure within the ventricles.
 * 6.** This pressure forces the atrio-ventricular valves to close and the semilunar valves to open.
 * 7.** Blood, under pressure, is forced into the arteries.
 * Right ventricle -> semilunar valve -> pulmonary trunk -> lungs
 * Left ventricle -> semilunar valve -> aorta -> the rest of the body

Since the left ventricle of the heart must pump blood to the rest of the body, it needs to pump blood out of the heart with considerable force. This is why the wall of the left ventricle of the heart is thicker than that of the right.


 * 8.** The atria begin filling again.
 * 9.** Pressure in the ventricles drops, causing the semilunar valves to close to prevent backflow of blood into the ventricles. When pressure is further reduced, the atrio-ventricular valves reopen and blood begins to pass from the atria to the ventricles.
 * 10.** The next heartbeat begins as the walls of the atria contract again, repeating the cycle.

The cardiac cycle is controlled by the sinoatrial node, located in the right atrium. This node, also known as the heart’s pacemaker, is made from specialized muscle cells which continuously send small electrical impulses at regular intervals into the walls of the right and left atria. This causes the atria to contract, allowing blood to be pushed out into the ventricles. The impulses then travel down to the atrioventricular (AV) node located near the top of the septum. This AV node delays the impulses in order to allow atrial contractions to finish before the ventricles contract. Connected to the AV node are specialized cardiac fibers known as the bundle of His. These send the impulses down the Bundle branches, past the apex and into the Purkinje tissue. Ventricular contraction is initiated at the apex of the heart and the Purkinje fibres spread along the base of the ventricles continue the contraction of the ventricles which sends the blood into the arteries. There are parts of the brain which also help control the pace of the heart beat. Signals sent from the vagus nerve (from the parasympathetic system) will slow the heart down and those from the sympathetic nerve (from the sympathetic nervous system) will increase the heart rate. Hormones can also control the heart rate. One example includes adrenalin (epinephrine) which increase the cardiac frequency. A last method of controlling the heartbeat is by implanting an artificial pacemaker in the place of a non functioning SA node. The pacemaker works just as well and does not prohibit the victim from engaging in normal exercises. (from: http://www.univie.ac.at/cga/courses/BE513/EKG/condHeart.gif)
 * 5.2.3 Outline the control of the heartbeat in terms of the pacemaker, nerves, and adrenalin.**


 * 5.2.4 Explain the relationship between the structure and function of arteries, capillaries and veins.**
 * Blood circulates throughout the body by contractions of the heart
 * **Blood Vessel** ||
 * **Job** ||
 * **Adaptation** ||
 * **Explanation** ||
 * Arteries ||
 * Carry blood away from the heart ||
 * # Thick muscular and elastic walls ||
 * 1. Blood leaves the heart under high pressure. The thick wall is needed to withstand and maintain the pressure. The elastic wall gradually reduces the harsh surge of pumped blood to a steadier flow. ||
 * Veins ||
 * Carry blood back to the heart ||
 * # Thinner walls than arteries
 * 1) Large lumen
 * 2) Valves ||
 * # Blood is now at a lower pressure so there is no need to withstand it.
 * 1) Provides less resistance to blood flow
 * 2) Prevents backflow ||
 * Capillaries ||
 * Exchange substances with body tissues ||
 * 1. Thin permeable wall
 * Exchange substances with body tissues ||
 * 1. Thin permeable wall

2. Small size ||
 * 1. Substances such as water and food can enter and leave the blood through capillary walls

2. Can reach inside tissues and between cells ||

About 8% of the human body is composed of blood. Plasma makes up about 50-55% of the blood and cells make up about 45-50%. -->Plasma is made up of: -90% water -10% proteins, dissolved food, hormones, and waste materials. -->Cells are composed of: -90% erythrocytes -leucocytes (where 70% are phagocytes (non-specific defense) and 30% are lymphocytes (produce antibodies)). -thrombocytes (platelets)
 * 5.2.5 State that blood is composed of plasma, erythrocytes leucocytes (phagocytes and lymphocytes) and plateletes.**

The function of the circulatory system is to transport nutrients, oxygen, carbon dioxide, hormones, antibodies and waste products in teh blood. The transport of oxygen and carbon dioxide involves erythrocytes. The rest are simply disovlved in the blood.
 * 5.2.6 State that the following are transported by the blood: nutrients, oxygen, carbon dioxide, hormones, antibodies, and urea.**