“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.

“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 atrium Left ventricle Pulmonary arteries

Bicuspid valve Aorta Right ventricle

Left atrium Tricuspid valve Pulmonary veins

Lungs Inferior vena cava Superior vena cava

Pulmonary semilunar valves Aortic 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, 250-350 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 artery

Pulmonary veins

Pulmonary veins

Aorta

Descending aorta (thoracic)

Tricuspid valveBiscuspid 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) (To lungs)

(From 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” 70-80 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)