structure of the heart

• what are cardiac muscles

  walls of the heart are made of thick muscular layers
• what are two properties of cardiac muscles?

  1. MYOGENIC - can contract and relax without nervous or hormonal stimulation
  2. never fatigue as long as oxygen and glucose is supplied
• what are coronary arteries ?

  they are blood vessels that surround the heart and branch out the aorta , they supply cardiac muscles with oxygenated blood
• what happens when a coronary artery is blocked?

  theres no oxygen being delivered so cells die as theres no respiration leading to a myocardial infarction (heart attack)
• what are the 4 chambers in the heart?

  right atrium , left atrium , right ventricle, left ventricle
• what are two features of the atria?

  1. thin muscular walls as they dont need to contract as hard because theres a short distance to the ventricle
  2. elastic walls to stretch when blood enters
• why do ventricles have thicker muscular walls to the atria?

  they pump blood to the rest of the body at higher pressures
• what is the difference between the right VENTRICLE and the left VENTRICLE?

  1. they have thinner walls than the left ventricle as the right pumps blood to the lungs
• why does the right ventricle have thinner muscular walls?

  • because it pumps blood to the lungs at lower pressures to prevent damage to capilliaries in the lungs and so blood flow is slower to allow time for gas exchange
• what do veins do?

  bring blood to the heart
• what do arteries do?

  take blood away from the heart
• what is the vena cava and what does it do?

  • vein
  • carried deoxygenated blood from the body to the right atrium
• what is the pulmonary vein and what does it do?

  • brings oxygenated blood from the lungs to the left atrium
• what is the pulmonary artery and what does it do?

  • artery
  • takes deoxygenated blood from the right ventricle to the lung
• what is the aorta and what does it do?

  • artery
  • takes oxygenated blood from the left ventricle to the body
• what are the two types of valves found in the heart?

  atrioventricular valves and semi-lunar valves
• where do you find the semi-lunar valves?

  in the aorta and pulmonary artery
• where do you find the atrioventricular valves?

  between the atrium and ventricles
• name the two atriventricular valves and where they are found?

  • bicuspid - left
  • tricuspid-right
• how do valves open and close?

  1. open when theres higher pressure behind the valves
  2. close when theres higher pressure in front of the valves
• what do valves do?

  they prevent back flow by making sure blood flows in one direction
• what is the septum?

  muscular layer separating the left and right side of the heart to help maintain oxygen concentration
• what are the three stages of the heart cycle?

  1. diastole
  2. atrial systole
  3. ventricular systole
• what is diastole?

  relaxing
• what is systole?

  contracting
• what happens in diastole?

  • the atrium and ventricles are relaxing
  • due to the large volume, blood flows into the atrium
  • pressure starts to rise
• what happens in atrial systole?

  • the ventricles are still relaxed
  • the volume in the atrium decreases and pressure start to increases
  • the atrioventricular valve opens and blood flows into the ventricles
• what happens in ventricular systole?

  • the ventricles contract after a short delay , increasing pressure beyond the atria
  • the atrioventricular valves close and semi-lunar valves open
  • blood is pushed out the ventricle and into the arteries
• what is cardiac output?

  the volume of blood leaving one ventricle in one minute
• how do you calculate cardiac output?

  cardiac output = heart rate × stroke volume

  
  

  heart rate is the number of times a ventricle contracts in one minute

  stroke volume is the volume of blood pumped out in a beat
• when do atrioventricular valves open?

  when theres higher pressure in the atrium than the ventricle
• when do the semi-lunar valves open?

  when theres higher pressure in the ventricle than the artery
• label when the valves open and close

  label

  A) AV valves close

  B) semilunar valves open

  C) semilunar valves close

  D) AV valves open

  
• label the heart

  the heart

  A) superior vena cava

  B) right pulmonary artery

  C) right pulmonary veins

  D) inferior vena cava

  E) aorta

  F) left pulmonary artery

  
• what type of circulatory systems do mammals have?

  a closed , double circulatory system
• why is it a closed, double circulatory system?

  closed - blood remains within vessles

  double - blood passes through the blood twice each circuit, one to the lungs and one to the body
• why do we need a closed, double circulatory system?

  • becuase blood is needed at different pressures as in the lungs it needs to be lower and for the body it needs to be higher
• what blood vessels are attached to the kidney?

  renal vein and renal artery
• layers of the arteries?

  1. muscle layer is thicker so it can control blood flow
  2. the elastic layer is thicker so it can maintain blood flow and recoil
  3. the walls are thicker so it can prevent the vessels bursting due to pressure
• what kind of lumen do arteries have?

  small lumes