biology

• The Heart


  A hollow, muscular organ that pumps blood throughout the body.

  
• septum


  Separates Oxygenated/ Deoxygenated blood
• atria


  top chambers of the heart
• ventricles


  bottom chambers of the heart
• wall of left ventricle

  -thicker than right ventricle

  -pumps blood to all parts of body
• tricuspid and bicuspid valves (3/2 flaps)

  -located between atria and ventricles

  -prevent backflow of blood
• chordae tendineae


  tendons that hold valves in place (heart strings)
• papillary muscle


  where tendons are attached to heart
• pacemaker


  A device that delivers electrical impulses to the heart to regulate the heartbeat
• vena cava


  Brings deoxygenated blood from the body to the heart

  
• pulmonary vein


  brings oxygenated blood to heart from lungs

  
• pulmonary artery


  brings deoxygenated blood from heart to the lungs

  
• aorta


  large artery brings oxygenated blood from heart to all around the body

  
• control of heartbeat


  -controlled by pacemaker (SA node), located in wall of right atrium

  -SA node sends out electrical signals that cause the atria to contract

  - signal is pivked up by AV node

  -AV node sends signals causing ventricles to contract
• systole


  Contraction of the heart muscle
• diastole


  relaxation of heart muscle
• effect of smoking on heart

  -nicotine increases heart rate and blood pressure

  -carbon monoxide reduces the amount of O2 carried by blood

  -other chemicals increase risk of clots
• effect of diet on heart

  -saturated fat is linked with high cholestrol

  -high sodium intake raises blood pressure
• effect of exercise on heart

  -exercise strengthens cardiac muscle

  -improves circulation and reduces cholestrol
• coronary artery (branched off the aorta)


  The artery that supplies heart tissue with oxygenated blood
• coronary vein


  Drains the heart muscle tissue of deoxygenated blood and returns it back into the right atrium.
• heart muscle


  -composed if cardiac muscle

  -contractile tissue

  -does not fatigue
• heart layers (3)


  Pericardium - outside, protection

  Myocardium - Cardiac muscle

  Endocardium - Endothelial cells

  
• Why do we need a circulatory system?

  - Removes waste products of metabolism to excretory organs

  - circulates 02 + Co2

  - Delivers nutrients to the body's cells
• closed system


  The blood always remains in the vessels

  - blood flow can be controlled

  - blood flows at high pressure, nutrients reach the cells quickly
• Capillaries


  The vessels in which material enters and exits
• pulmonary circuit


  carries blood to the lungs for gas exchange and returns it to the heart
• systemic circuit


  Circuit of blood that carries blood between the heart and the rest of the body.
• Arteries


  Blood vessels that carries blood away from the heart
• Veins


  Blood vessels that carry blood back to the heart
• What are veins and arteries composed of?

  Connective tissue - collagen + elastic fibres

  Muscle and elastic fibre

  Endothelium - endothelial cells

  
• skeletal muscle


  The blood flow in veins is helped along by the squeezing of the skeletal muscles
• Differences between arteries and veins

  Arteries have narrower lumen.

  Veins have larger lumen, valves to prevent backflow due to low pressure of blood.

  
• portal system


  A blood pathway that begins and ends in capillaries. E.g. Hepatic portal vein - intestines- liver
• Plasma


  yellow liquid -90% water

  -plasma proteins, clotting proteins (fibrogen), antibodies, salts

  - 55% of the blood volume

  - Most Co2 transported as hydrogencarbonate ions

  
• Function of blood plasma

  Transport nutrients, waste, Co2

  
• white blood cells (leukocytes)

  Contain:

  2 types:

  Made in:

  Function:

  Large nucleus

  - Monocytes

  - Lymphocytes

  Made in: Red bone marrow

  Function: fight infection
• red blood cells (erythrocytes)

  Consist of:

  Shape:

  Adaptions:

  Made in:

  Function:

  No nucleus/mitochondria

  Haemoglobin (4+ iron)

  Shape: Biconcave

  Large surface area for more rapid diffusion of gases

  Flexible - fit into narrow vessels

  Made in: Red bone marrow, sternum, ribs, breast bone

  Function: Transport O2
• Platelets (thrombocytes)

  Function:

  Fragments of cells

  Function: clotting

  
• Monocytes


  Phagocytes - cells that move to surround and engulf bacteria or pathogens

  Monocytes -> Macrophages