These in depth notes cover everything you will need to pass the human anatomy and physiology exams. Notes cover the anatomy and physiology of the cardiovascular system - the heart and blood vessels, the conductive system of the heart and contractions
The Cardiovascular System
• Organ system
o Conveys blood through blood vessels to and from all body parts
o Carries nutrients and oxygen to tissues, removes carbon dioxide and other
wastes
o A closed tubular system in which blood is propelled by the heart
• Other important functions
o Helps to protect the body against disease and infection
o Clotting stops bleeding after injury
o Transports hormones to target cells and organs
o Helps regulate body temperature
• Cardiovascular system serves a number of important functions, most of which
support other physiological systems
• Major functions fall into 5 categories
o Delivery
o Removal
o Prevention
o Maintenance
o Transport
• All bodily functions and virtually every cell in the body depends in some way on the
cardiovascular system
• Any system of circulation requires 3 components
o A pump (the heart)
o A system of channels (blood vessels)
o A fluid medium (blood)
• The heart
o Beats 100,000 times per day
o Pumps 1.5 gallons (12 pints) of blood every minute
o 600,000 miles of blood vessels
o Apart from the corneas of the eye, every cell receives blood
o The heart creates enough energy every day to drive a truck 20 miles
o Heart begins beating at 4 weeks after conception
• Heart anatomy
o Located in the thoracic cavity medial to the lungs and posterior to the sternum
o Backside of the heart is known as the dorsal side and the front side towards
the chest is known as the ventral side
o Heart wall has 3 layer
▪ Double layered serous membrane (pericardium) surrounds the heart
(sac like)
• Parietal pericardium - outer layer, connective tissue, surrounds
the roots of the heart's major blood vessels. Attached by
ligaments to the spinal column, diaphragm and other body
parts
• Visceral pericardium - inner layer attached to the heart muscle.
Between two layers in the pericardial cavity. Contains
pericardial fluid (lubrication) which allows the heart to expand
and contract
▪ Epicardium
• Outside layer
• Parietal pericardium
, • Connective tissue layer
▪ Myocardium
• Middle layer (95% of heart wall)
• Mostly cardiac muscle
▪ Endocardium
• Inner layer
• Thin layer of endothelium overlying connective tissue
o 4 major cell types in the heart
▪ Cardiac fibrolasts (CFs) (mesenchymal cells)
• Produce the extracellular matrix (ECM), the scaffold of the
heart and are thought to constitute more than half of all heart
cells
• Contribute structurally, biochemically, mechanically and
electrically to the properties of the heart
• Mesenchymal stem cells (MSCs) are multipotent stem cells
found in bone marrow that are important for making and
repairing skeletal tissues, such as cartilage, bone and the fat
found in bone marrow. With age and disease, MSCs
predominantly convert into lipid-accumulating fat cells.
▪ Cardiomyocytes
• Estimated to provide about 30% of the total cell number but
account for over 70% of the total cardiac mass because of
their large volume
• These are cells responsible for heart contractions
• Cardiomyocytes stop cell division immediately after birth and
are thought to adapt subsequently to the demands placed on
the heart by undergoing hypertrophy without cell division
• A cardiomyocyte is the cell responsible for the contraction of
the heart – utilising an intricate network of contractile proteins
and ion transporters for this work – with the main purpose of
effectively executing the contraction-relaxation cycle.
• The individual cardiac muscle cell (cardiomyocyte) is a tubular
structure composed of chains of myofibrils, which are rod-like
units within the cell. The myofibrils consist of repeating
sections of sarcomeres, which are the fundamental contractile
units of the muscle cells.
▪ Smooth muscle cells
• Support the vascular system
• Involuntary, non-striated muscle
• Smooth muscle consists of thick and thin filaments that are not
arranged into sarcomeres, giving it a non-striated pattern
▪ Endothelial cells
• Form the interior lining of the heart, blood vessels and cardiac
valves
o Heart chambers
▪ 4 chambers
▪ Right and left side
▪ Act as separate pumps
▪ 2 upper chambers known as atria/atrium (receiving chambers)
▪ 2 lower chambers known as ventricles (sending units)
▪ Right side of the heart = pulmonary circulation
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