Transcript Cardiovascular 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
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
• Using your textbook as a resource, describe the following terms:
• Myocardium:
•Syncytium:
•Pericardium:
•Epicardium:
•Endocardium:
Aorta
Superior vena
cava
Pulmonary artery
Pulmonary
artery
Pulmonary
veins
Pulmonary veins
Pulmonary
semilunar valve
Left atrium
Right atrium
Biscuspid valve
Tricuspid valve
Right ventricle
Aortic semilunar
valve
Inferior vena
cava
Left ventricle
Interventricular septum
Descending aorta
(thoracic)
Explain the role the papillary muscles and chordae tendinae
have with the valves of the heart
What is the role of valves?
BLOOD
BLOOD
• Specialized bodily fluid whose main role is to transport O2, CO2 and nutrients
throughout the body
Blood Composition
• Plasma (55%) –water, dissolved nutrients,
proteins, ions and gases
• Red Blood cells (45%)
• erythrocytes –transport O2/CO2
• hemoglobin
-O2/CO2 can bind to this
molecule  to deliver O2
to tissues and remove CO2
Blood Composition
• Plasma (55%) –water, dissolved nutrients,
proteins, ions and gases
• Red Blood cells (45%)
• erythrocytes –transport O2/CO2
• hemoglobin
-O2/CO2 can bind to this
molecule  to deliver O2
to tissues and remove CO2
• White Blood cells (< 1%)
• leukocytes  protect body from disease
• Platelets  fragments of blood cells
-very important part of blood clotting
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
Oxygenated blood
Deoxygenated blood
1. Through the Heart
(To lungs)
(To lungs)
(From lungs)
(From lungs)
(To body)
2. Vascular Circulation
• network of vessels that transport blood throughout the 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)
-video
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
If damaged
Internodal pathways carry signal through atria causing blood to ventricle
Pacemaker
Signal passes atrioventricular node = passes signal into ventricles
Passes along septum = bundle of HIS (atrioventricular bundle)
Signal splits left and right towards Purkinje fibres
Heart beat video
Signal to ventricles
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
Reached AV node
P Wave = depolarization; spreading of signal through atria (SA node firing)
QRS complex = depolarization of ventricle; highest point, because largest pressure
needed
T Wave = repolarization of ventricles (similar size and shape to P wave)