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Cardiovascular System (Heart (Myocardium Microscopic Anatomy (Cardiac…
Cardiovascular System
Heart
Pericardial Membranes
Fibrous Pericardium
- Sac the covers and surround the heart
- Dense Irregular Connective Tissue on top of the muscle of the heart
- Extends from the Diaphragm to the roots of the largest vessles
- Keeps the heart in place
- Keeps the heart from over filling
- Not vert flexible
Serous Pericardium
- Just deep to the Fibrous Pericardium
- Areolar Connective Tissue and Simple Squamous Epithelium
- Double Layered Membrane Parietal Layer (Outer) that is continuous with the Visceral Layer (Inner) also called the Epicardium
Pericardial Cavity
- Between the Parietal and Visceral Layers
- A Slit like space
- Epithelial cells produce a lubricating film called Serous Fluid
- Serous fluid reduces friction between the beating heart and the outer wall of the pericardial sac
Layers of the Heart Wall
Endocardium
- Inner most layer that covers heart chambers and valves
- Located on the walls of the ventricles
- Comprised of Endothelial Cells
- Simple Squamous Epithelium resting on a layer of connective tisuse
Myocardium
- Forms the bulk of the heart
- Muscular Tissue or Cardiac Muscle
- Muscle shaped in a spiral formation to squeeze the blood out of the heart
Epicardium
- Visceral Pericardium
- Epithelial Membrane
- Often contains fat in older adults
Conduction System
- 99 % Contractile Cells
- 1% Electrical Cells
Sinoatrial Node (SA Node)
- Located near the Superior Vena Cava
- Pacemaker of the heart
- Generates an electrical signal sent to both Atria via Gap Junctions
Atrioventricular Node (AV Node)
- Receives action potential from SA Node
- Delays signal for a short time while ventricles fill with blood
- Contraction happens slightly after depolarization
- Atria and Ventricles contract at slightly different times
Atrioventricular Bundle (AV Bundle/Bundle of His)
- Area from the Atrioventricular Node to the first branch
- Passes the signal through the heart at the top of the Interventricular Septum
Right and Left Bundle Branches
- A Split of the Bundle Branches down each side of the Interventricular Septum to go to right and left side of the heart
Subendocardial Branches (Purkinje Fibers)
- Part at the Apex of the heart and carry the electrical signal up the heart walls
Heart Valves
Semilunar Valves
- Found in the Pulmonary Valve and the Aortic Valve
- Pushes blood out of the heart when pushed open by contraction of the heart
- Blood that gets pulled back is caught by the cups in the valve
- One way traffic
Bicuspid/Mital/Left Atrioventricular Valve
- Located between the Left Atrium and the Left Ventricle
- Papillary muscle pulls on the Chordae Tendineae when the heart contracts to close the valve
Tricuspid/Right Atrioventricular Valve
- Located between the Right Atrium and the Right Ventricle
- Papillary muscles pulls on the Chordae Tendineae when the heart contracts to close the valve
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Blood Vessels
Artery Types
Conducting/Elastic Arteries
- Move large amounts of blood
- A lot of Elastic Fibers
- Stretch and Recoil to propel blood forward
- Acts like a one way pump
- Found in: Aorta, Pulmonary Trunk, large branches of the Aorta
Muscular/Distributing Arteries
- Has more muscle for its size then other arteries
- Takes blood to organs or to parts of organs
Arteriole Arteries
- Smallest of all the arteries
- 1 to 2 layers of Smooth Muscle
- Changes diameter to regulate flow of blood
Capillary Types
Continuous Capillaries
- Most common type
- Found in the Central Nervous System, Lungs, Skeletal Muscle and Smooth Muscles
- Least leaky type
Fenestrated
- Has Window like pores
- More leaky then continuous
- High rate of exchange
- Found in: Small Intestines, Kidneys, Choroid Plexus, Endocrine Glands
Sinusoid
- Large and Winding
- Exchange of larger macro-molecules like proteins and whole cell
- Found in: Liver, Red Bone Marrow, and Spleen
Capillary Bed
- Network of blood vessels
- Has an artery on one side and a vein on the other
- Capillaries lie in between the two
Vein Types
Large Veins
- Superior and Inferior Vena Cava
- Located deep within the body
- Accompanied by deep veins
Medium Veins
- Have Valves
- Look like Semilunar Valves of the heart
- Fewer elastic fibers
Venule
- Smallest of the veins
- Much like capillaries
- Still some exchange
- 1 to 2 layers of smooth muscle
Blood
Plasma
- Liquid Portion of Blood
- 90% Water
- Contains more than 100 different molecules
- Ions, Amino Acids, Lipids, Hormones, Vitamins, etc.
Cells
Erythrocytes
- Red Blood Cells
- Bags of Hemoglobin
- Contain Iron and binds to oxygen
- Shape generated during creation with the nucleus is removed
- Live for 100-120 days
Leukocytes
- White Blood Cells
- Body's defense against disease
Neutrophils
- Multiple curved shaped Nucleus
- Pale Red and Blue
- Cytoplasmic granules
Basophils
- Freckled like Nucleus
- Purple and Black cytoplasmic granules
Lymphocytes
- Large Sphere Nucleus
- Nucleus takes up most of the cell
- Rim of light blue cytoplasm
Monocytes
- Large Kidney shaped Nucleus
- Pale Blue cytoplasm
Eosinophils
- Two sphere Nucleus
- Red Cytoplasmic granules
Platelets
- Created in Bone Marrow
- Called Thrombocytes
- Disc shaped, plasma membrane fragments of cytoplasm
- Fragments are larger cells call Megakaryocytes
- Participate in Blood Clot Formation