6.2 The Blood System

Draw and label a diagram of the heart showing the four chambers, associated blood vessels, valves and the route of blood through the heart.

Draw and label a diagram of the heart showing the four chambers, associated blood vessels, valves and the route of blood through the heart. ( THIS WILL HELP YOU)

Who was our boi William Harvey?

Back in the day, it was believed that blood was made from digested food and taken to tissues where it was used. Blood had to be replenished by eating again. Also, the function of the heart was to produce heat.

• Harvey did a study on animals, in which he found that the larger and necessary vessel size and the amount of blood moving through the body could not be consume quickly.

• Harvey proposed that the circulation of blood and its pump around by the heart.

  • This idea showed how blood was not consumed by the body

  • Showed valves in the heart and veins ensured one-way flow of blood.

  • Predicted the existance of capillaries

What does the Coronary arteries provide?

• Provide oxygen and nutrients to the muscles of the heart.

What are the causes of Coronary Blockage?

• High cholesterol

• Smoking

• High blood sugar

• Genetic factors

What are the consequences of coronary blockage?

• Coronary artery disease

• High blood pressure

• Chest pain

• Diabetes

• Death

Coronary Blockage: OMG what if the plaque ruptures

If the plaque ruptures, it forms a coronary thrombosis and blocks the coronary artery, it can cause the heart to beat at uncordinated way (fibrillation) and this can result in a heart attack.

Explain the action of the heart in terms of collecting blood, pumping blood, and opening and closing of valves.

1. The right atrium collects blood from the superior and inferior vena cava.

2. The left atrium collects blood from the pulmonary veins.

3. This blood flows to the right and left ventricle, which pumps blood into the arteries.

4. Blood flow is controlled by the atrioventricular valves and semi-lunar valves.

5. When the Atria contracts the blood flows through the open atrioventricular valves, into the ventricle. '

6. At this stage, the semi-lunar values are closed so the ventricle fills with blood.

7. The ventricle contracts which causes a rise in pressure.

8. This causes the atrioventricular values to close and prevent backflow of blood into the atria.

9. Then semi-lunar values open, allowing the expulsion of blood into the arteries

10. As this happens, the atria start to fill with blood again.

11. The ventricles stop contracting leading to a fall in pressure which causes the semilunar valves to close, preventing the back flow of blood from the arteries.

12. When the ventricular pressure drops below the atrial pressure the atrioventricular valves open again and the cycle repeats. 

Simplier action of the heart ( SIMPLE)

• Blood is collected in the atria (plural form of atrium).

• Walls of atria contract, pushing blood past the atria-ventricular valves which are forced open.

• Blood is able to fill the ventricle because the semi-lunar valves (at other end) are closed.

• Atria relax.

• Walls of ventricles contract, forcing the atria-ventricular valves closed to prevent backflow. This also forces open the semi-lunar valves allowing blood into arteries. At the same time blood is again being collected in the atria from the veins.

• Ventricles relax while pressure in arteries force semi-lunar valves closed to prevent backflow.

Additionally,

1. The right atrium collects blood from the superior and inferior vena cava.

2. The walls of the Right atrium contract, pushing blood through the (Tricuspid Valve) and past the atria-ventricular (Right ventricle), which is force to open.

3. Blood fills the right ventricle because of the semi-lunar valves (Pulmonary valve) is closed

4. Atria Relax

5. Walls of the ventricles contracts, forcing the atria-ventricular valves to closed to prevent back flow.

6. This forces open the semi-lunar valve (Pulmonary Valve) allowing blood to flow to the arteries. (to the lungs)

7. Blood is then again collected in the atria from the vein ( pulmonary vein)

8. Blood is collected in the left atrium, The walls of the left atrium contract, pushing blood to the left ventricular ( Atria-ventricular opens). Causes the left ventricle to fill, since the semi-lunar value is closed.

9. Artoa value closed,

10. Atria relaxes,

11. Left ventricle contracts, forcing Aortic value to open and blood flows out the Aorta to the body.

12. Ventricles relax while pressure in arteries force semi-lunar valves closed to prevent backflow.

Outline the control of the heartbeat in terms of myogenic muscle contraction, the role of the pacemaker, nerves, the medulla of the brain and epinephrine (adrenaline).

• A heart muscle can contract itself, without stimulation from a nerve.

• Heartbeat orignates withiin the muscle of the heart itself, without any stmulation from a nerve. This is called myogenic muscle contration.

• When one muscle celll contrats, it stimulates other around it to contract.

• This is initaiated by the pacemaker in the wall of the right strium (SA node) with special muscle fibers radiating both atria.

• A second structure (AV node) picks up the stimulation and passes it to the ventricles to trigger their contraction.

• Peace maker sends a signal, heartbeat as a result

• CONTROL HEARTBEAT PART

• The pacemaker is under the influence of nerves and adrenaline.

• One nerve carries messages from the medulla of the brain to the pacemaker and speeds up the beating of the heart.

• Another nerve carries messages from the medulla of the brain to the pacemaker and slows down the beating of the heart.

• Finally, adrenaline (epinephrine) is carried by the blood and once it reaches the pacemaker it signals it to increase the beating of the heart.

IDENIFTY THE SA & AV NODE< BUNDLE OF HIS< P FIBERS< LBB< IS

IDENIFTY THE SA & AV NODE< BUNDLE OF HIS< P FIBERS< LBB< IS

Control of Heartbeat

• Control of the heartbeat is a reflex. It is involuntary.

• The medulla of the brain controls involutary actions. The heart receives impulses from this region from two nerves

  • Cardiac nerve, stimulates the heart rate to increase

  • Vagus nerve: triggers the heart to slow down

    • The nerve influnces the rate of the heartbeat, however it does not cause heartbeat.

      • In addition to an increase of heart rate through the nerve, epinephrine is a hormone carried in the blood to the pacemaker that also increases the heart rate.

Explain the relationship between the structure and function of arteries, capillaries and veins.( Arteries)

Arteries

• Has a thick muscular wall to withstand pressure

• They also have thick layers of circular elastic fibers and muscle fibers to help pump blood through after each contraction of the heart.

• Thick outer layer of longitudinal collagen and elastic fibers to avoid leaks and bulge

• 3 Layers in walls

• High pressure

• From venricles to capillaries/ away from heart

• Narrow lumen to keep high pressure

• No valves

Explain the relationship between the structure and function of arteries, capillaries and veins ( Capillaries)

• Single layer of cells

• Very thin/ site of exchange with tissues by diffusion

• From arteries to veins

• Narrow lumen - capillaries can fit in a small space, increasing the surface area for diffusion.

• No valves

• Pores within their wall which allow some plasma to leak out and form tissue fluid. Phagocytes can also pass through these pores to help fight infections

Explain the relationship between the structure and function of arteries, capillaries and veins ( Vein)

• Low pressure

• 3 layers in walls

• Thinner walls than artery because of less pressure

• From capillaries toward the heart (atria)

• Wide lumen for less resistance

• Vales to keep blood flowing in one direction/prevent backflow.