(a)++Heart+structure


 * __ (A) The Heart __**

(__1) Draw a good clear diagram to show the layout of the heart. Include relative wall thicknesses and all names.__

2. Draw a diagram to show the main blood vessels entering & leaving the heart. __ 3. What is a valve, & what is its job? Draw a diagram to show the location of the main valves. __ ||   || The heart has four chambers:
 * Valves are flaps of tissue without muscle. Its function is to control the direction of blood flow. As long as the blood is flowing in the right direction, the valves will remain open. However, when blood flows in the wrong direction, the valves are pushed shut.
 * __4. Describe what each of the 4 chambers of the heart does__


 * -The Right Atrium **
 * This chamber of the heart received oxygen-depleted blood (they receive this from the superior and inferior vena cava). It also received blood from the coronary sinus, the venous outlet and also from the coronary circulation.
 * Moreover, the right atrium has an effect of the heart right (since it has baroreceptors on its inside surface, which responds to falling blood supply by increasing the heart rate).
 * The wall of the right atrium is around 2mm think (this is because of the low pressure of this chamber as well as the ease of pumping to low pressure areas [the right ventricle)
 * -The Right Ventricle **
 * The right and left ventricle are separated by the septum. The job of the right ventricle is to eject blood through the pulmonic valve into the pulmonary arteries.
 * The wall of the right ventricle is 4 - 5 mm thick.
 * -The left atrium **
 * Just like the right atrium, the left atriums function are: atrial kick for the left heart, influence the heart rate, and it also has endocrine qualities.
 * The left atrium wall is a little larger than the right atrium (3mm)
 * -The left ventricle **
 * This is the largest chamber of the hear, and it account for the majority of the anterior and left lateral surfaces of the hart. also, the lift ventricle occupies the vast majority the hearts apex.
 * The wall of this chamber is 8 - 15 mm think.

__6. We need to know the overall process of how the heart beats, but not the specific chemical messengers involved.__ a. Define myogenic & pacemaker then describe how our heart beats (i.e. describe the nerve impulses).

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**Pace maker:** a specific region from the right atrium (aka. Sino-Atrial Node (SA node)) which generates nerve impulses which makes the muscles contract, this is what keeps the heart beating. ======

b.What is the sequence of contractions? ======Right atrium, right ventricle, left atrium, left ventricle. ======

Humans (mammals) have double circulation, meaning that the blood coming from the body goes through the heart, to the lungs, back to the heart and then to the body. Therefore, the heart has a left and right side (each side has an atrium and a ventricle) Atria - collects bloods and walls are thin Ventricles - walls are thick and muscular since they pump blood into the arteries. (left ventricle has thicker wall than right since it pumps the blood through the entire body)
 * (7) What type of circulation system do humans have?**

(9.) Vasoconstriction is the constricting of blood vessels causing them to become narrow and more stressed. Vasodilation is the increase in thickness of blood vessels and also strains the heart because of the increase in area and increase in force needed to move blood through. The following nutrients are transported by blood:Nutrients, oxygen, carbon dioxide, hormones, antibodies, urea and heat Transport of oxygen and carbon dioxide is associated with the erythrocytes while other substances listed are dissolved in blood ||  ||
 * (12)What are the two main functions of blood? List the substances that are transported. **