Anatomy and physiology

• Valves

  •Major vessels that act as entry and exit points are at the top of the heart

  •To ensure smooth passage of blood through the heart, a number of VALVESexist

  •Valves ensure blood only flows in one direction, and the ‘lub dub’ sound of the heart

  •The ‘lub’ is the sound of the bicuspid and tricuspid valves (atrio-ventricular valves) closing

  •The ‘dub’ sound is the sound of the pulmonary and aortic valves (semi-lunar valves) closing
• Firstly, oxygenated blood enters the heart  from the lungs via the pulmonary veins and then enters the left atrium
• Structure of the Heart

  Secondly, the blood is pumped from the left atrium, through the mitral valve into the left ventricle.
• Structure of the Heart

  Next, the blood is strongly pumped from the left ventricle through the aortic valve into the aorta where it travels around the body.
• Structure of the Heart

  Now the blood returns from the rest of the body, deoxygenated. It returns via the 2 vena cava, the superior/inferior and the blood enters the right atrium.
• Structure of the Heart

  The blood is pumped through the tricuspid valve and into the right ventricle.
• Structure of the Heart

  It is then given a strong pump from the right ventricle and goes through the pulmonary valve and into the pulmonary artery where it will be re-oxygenated at the lungs.
• Blood transport 

  The heart operates a double circulatory system in which blood flows through the heart twice.

   
• HEART LABELLED

  
• HEART DURING SYSTOLE AND DIASTOLE

  
• Handy Tips - Blood flow through the heart

  •Blood comes into the heart from the body

  •It then has to pass to the lungs to collect  oxygen

  •This is called a double circulatory system

  •After it returns to the heart it leave again to be transported to the body.
• Handy Tips continued…

   

  •Valves prevent backflow

  •When pressure in ventricles exceeds that in the atrium the bicuspid/tricuspid valves shut

  •This makes the first noise we hear with a stethoscope.

  •Tendinous chords attached to Papillary Muscles prevent valves turning inside out.

  •Semi-lunar valves prevent backflow in the pulmonary artery and dorsal aorta.

  •Closure of these makes the second noise of the heart beat. (hence lub-dub)
• THE HEART

  
• MESENTERIC ARTERIES

  
• Blood inside of digestive tract?

  Digested molecules of food, as well as water and minerals from the diet, are absorbed from the cavity of the upper small intestine. The absorbed materials cross the mucosa into the blood, mainly, and are carried off in the bloodstream to other parts of the body for storage or further chemical change. This part of the digestive system process varies with different types of nutrients.
• What Happens to Blood in the Liver

  1. Liver stores glucose when we eat

  2. Liver puts glucose into blood when blood glucose level goes down

  3. Liver takes protein and fat and turns it into glucose

  4. Liver metabolizes (breaks down) many things in the blood

  5. Liver stores (keeps) vitamins and minerals

  6. Liver makes many proteins
• Glucose storage and release

  Liver stores glucose when we eat and then puts the glucose into the blood when our blood glucose level goes down
• Glucose production from protein and fat

  Liver takes protein and fat and turns it into glucose
• Things the liver metabolizes (breaks down) in the blood

  • hemoglobin
  • proteins like enzymes, insulin, and serum amyloid a
  • Ammonia
  • toxins (substances that are poisons) and waste from the body
• Vitamin and mineral storage

  Liver stores (keeps) vitamins and minerals
• Proteins made by the liver


  • proteins that make your blood clot – called coagulation proteins
• The blood enters the nephron via the renal artery and leaves via the renal vein. At the glomerulus the blood is filtered and the filtrate gathers in the bowman's capsule. The filtrate then passes along the tubule to the communal collecting
• Double pump

  •Left side of the heart – The SYSTEMIC CIRCULATION

  •Circulating oxygen rich blood through the body

  •Right side of the heart – PULMONARY CIRCULATION

  •Circulating oxygen poor blood back to the lungs
• The Heart

  The Heart muscle acts as a ‘double pump’, this means that it pumps blood around the body and around the heart itself and also from the heart to the lungs
• The heart requires a lot of oxygen and nutrients

  •Some oxygenated blood leaving the left ventricle goes directly to the heart through the coronary Arteries.

  •These branch many times to supply oxygen and nutrients throughout the cardiac muscle.

  •When these get blocked a heart attack is likely and bypass surgery required.
• WHY IS THE HEART REFFERRED TO AS A DOUBLE PUMP?

  This is why

  
• SYSTEMATIC VS PULMONARY CIRCULATION

  
• Cardiac muscle

  Myogenic - can contract and relax without receiving impulses from nerves
• Control of heart beat

  1. Cardiac muscle contracts and relaxes

  2. Sends regular waves of electrical activity over both atrial walls

  3. Wave of electricity transferred from SAN to AVN

  4. AVN sends waves of electrical activity down Bundle of His

  5. Bundle of His sends impulses through Purkyne Tissue in both ventricles

  6. Cycle begins again for next heartbeat
• SAN (Sino-atrial Node)

  Found in the Right Atrium, sets the rhythm of the heartbeat by sending regular waves of electrical activity over both atrial walls
• AVN (Atrio-Ventricular Node)


  Receives wave of electricity from SAN and sends waves of electrical activity down the Bundle Of His
• Bundle Of His

  Sends impulses through the Purkyne Tissue in both ventricles, making them contract simultaneously
• Electrical impulse from SAN in R.Atrium
• Wave of electrical activity is transferred from SAN to the AVN
• Both atria contract simultaneously
• Both ventricles contract simultaneously
• Words to listen for:

   

  Sino-Atrial Node

   

  Action potential

   

  Purkinje fibres

  Demonstrate the learning

  The average resting heart rate is 72 bpm.  
• The average resting heart rate is 72 bpm.  

  The stimulus for the heart beat is myogenic i.e. it arises within the heart muscle itself due to the SAN or pacemaker.  

  However, heart rate and stroke volume (volume of blood pumped per beat) can be altered by the autonomic nervous system
• Atrioventricular (AV) Node

  1.When the impulses generated by the SA node reach the AV node, they are delayedfor about a tenth of a second.

  2.This delay allows the atria to contract, thereby fully emptying of blood. 

  3.The AV node then sends the impulses down the Bundle of His.

  4.This bundle of fibers branches off into two bundles and the impulses are carried down the centre of the heart to the left and right ventricles = Purkinje fibres
• Stroke Volume

  The amount of blood pumped by the left ventricle of the heart in one contraction