“related to the heart”

Today’s lesson is going to look at 3 different aspects: Anatomy of the human heart The heart beat The human vascular system

Right atriumLeft ventriclePulmonary arteries Bicuspid valveAortaRight ventricle Left atriumTricuspid valvePulmonary veins LungsInferior vena cavaSuperior vena cava Pulmonary semilunar valvesAortic semilunar valves From these words below, review your knowledge of circulation by tracing the pathway of the blood (begin from the blood entering the heart from the body)

The HEART Once thought by ancient cultures to be the centre of everything for the body: wisdom, emotion, personality, memory and the soul Found in the middle of the chest, the heart is a fist-sized, gram hollow organ Main function is to pump blood throughout the body At rest = 5L/min At max = 25L/min Pericardium: two-layered fluid-filled membrane that surrounds the heart and prevents friction between the heart and other tissues and organs How much blood does your heart pump in your lifetime?

Superior vena cava Inferior vena cava Right atrium Left atrium Right ventricle Left ventricle Pulmonary artery Pulmonary veins Aorta Descending aorta (thoracic) Tricuspid valve Biscuspid valve Pulmonary semilunar valve Aortic semilunar valve Interventricular septum Coronary blood vessels

Aristotle (384 – 322 BC) -earliest most renowned philosopher in Ancient Greece -writings covered many subjects including: physics, poetry, theatre, logic, linguistics, politics, ethics, biology and zoology Thoughts on the brain: It was Aristotle’s belief that the function of the brain was to keep the body from overheating. A “compound of earth and water,” brain matter “tempers the heat and seething of the heart” (The Parts of Animals). Blood rises from the fiery region of the chest until it reaches the head, where the brain reduces its temperature “to moderation.” The cooled blood then flow back down through the rest of the body. Carr, Nicholas, “What the Internet is doing to our brains.”(2011)

BLOOD CIRCULATION 1. Through the Heart Oxygenated blood Deoxygenated blood (To lungs) (From lungs) (To body)

2. Vascular Circulation network of vessels that transport blood throughout the body Use your textbook to help label the major artery and veins of the human body.

AORTA ARTERIES Arterioles CAPILLARIES Venules VEINS

2. Vascular Circulation network of vessels that transport blood throughout the body Arteries thick muscular walls blood AWAY from the heart (oxygenated, except?) very elastic  stretch and recoil  movement of blood high pressure blood Arterioles control regulation of blood distribution to various tissues smaller, surrounded by rings of tissue nervous system  constrict/dilate rings autoregulation  chemicals released by tissues (nitric oxide) -causes arterioles to relax  increased BF -localized blood flow?

Capillaries smallest vessels, only one blood cell can pass at a time most important of all vessels -site of gas exchange for the human body O2 from blood to tissues; CO2 from tissues to blood  DIFFUSION (among other gases and nutrients)

VEINS thin (venules) to thick (vena cava) as move away from capillaries blood back to the heart (deoxygenated, except?) valves  one-way  blood only back to heart Type of pressure? Low + gravity  problem? blood back to heart 3 ways to help 1) Skeletal muscle pump –each muscle contraction, blood is pushed up veins (one way valve)  one direction of flow 2) Thoracic pump –inhalation  chest pressure low + higher pressure adominal  movement of blood from hi to low pressure 3) Nervous system –same process as arterioles (venoconstriction)

The Cardiac Cycle Use your textbook to define the following terms: Cardiac cycle Diastole Systole SYSTOLE “lubb” Atrioventricular valves closing Pressure in arteries upon contraction DIASTOLE “DUBB” Semilunar valves closing Pressure in arteries during relaxation Blood pressure problems?

The Heart Beat (Excitation of the heart) cardiac cells + electricity  excitable  contraction  blood pumping specialized tissues help regulate and coordinate this activity Sinoatrial node (SA node) = initiates electrical signal (autonomic) “pacemaker” bpm Internodal pathways carry signal through atria causing blood to ventricle Signal passes atrioventricular node = passes signal into ventricles Passes along septum = bundle of HIS (atrioventricular bundle) Signal splits left and right towards Purkinje fibres Signal to ventricles If damaged Pacemaker Heart beat video

Stimulation by the nervous system can either speed up or slow down this process Increase or decrease the heart rate

But how can we visualize a heart beat? Electrocardiogram (ECG) “graphical representation of the electrical sequence of events that occurs with each contraction of the heart” - each of the electrical waves of the contraction have been named

P Wave = depolarization; spreading of signal through atria (SA node firing) Reached AV node QRS complex = depolarization of ventricle; highest point, because largest pressure needed T Wave = repolarization of ventricles (similar size and shape to P wave)