Flashcards in CIRCULATORY SYSTEM PT 1 - HEART Deck (59):
Describe the size/positioning/inferior attachment of the Heart.
- Size of a fist
- Middle of the mediastinum with 2/3rds of mass on the left
- Attached to diaphragm inferiorly
The inferior portion of the heart is called?
The superior portion of the heart is called?
Mass of organs between Lungs
Name the structures that border the Mediastinum.
Superior: 1st rib
What are the structures that make up the Mediastinum?
What is Pericardium? Name the layers.
A two-layered CT membrane surrounding Heart
Fibrous and Serous
Describe Fibrous Pericardium.
A inelastic, dense irregular CT holding Heart in place and allows movement
Describe Serous Pericardium.
Deep to Fibrous, forming a double layer around Heart
Describe the Parietal Layer of the Serous Pericardium.
Outer layer fused to Fibrous Pericardium
Describe the Visceral Layer of the Serous Pericardium.
Inner layer attached to Heart muscle
What is the Pericardial Cavity?
Space between the Parietal and Visceral layer filled with pericardial fluid to reduce friction
Name the layers that make up the Hearts walls. From superficial to deep.
Describe the Epicardium layer.
aka. Visceral layer of Serous Pericardium
Outer layer of simple squamous epithelium and CT with a smooth, slippery texture
Describe the Myocardium layer.
Cardiac muscle tissue - site of contractions
Describe the Endocardium layer.
Deep layer providing a smooth lining for chambers and valves
Simple squamous epithelium lining cavities of heart, blood and lymph vessels. Found in Endocardium layer
What is a Septa?
Dividing walls in heart
What does the Interatrial Septum divide?
Divides 2 Atria
What does the Interventricular Septum divide?
Divides 2 ventricles
What is the function of Veins?
Carry blood towards Heart
What is the function of Arteries?
Carry blood away from Heart
Explain the blood flow function of the Right Atrium.
- Receives blood from 3 veins
- Exits through the Tricuspid Valve (Right A-V Valve)
- Into the Right Ventricle
Name the 3 veins entering the Right Atrium.
Superior Vena Cava
Inferior Vena Cava
Explain the blood flow function of the Right Ventricle.
- Receives blood from Right Atrium
- Ejects through Pulmonary Semilunar Valve
- Into the Pulmonary Trunk
- Suppling R and L Pulmonary Arteries (Lungs)
Explain the blood flow function of the Left Atrium.
- Receives blood from 4 veins (from lungs)
- Exits through Bicuspid/Mitral Valve (Left A-V Valve)
- Into the Left Ventricle
Explain the blood flow function of the Left Ventricle.
- Receives blood from Left Atrium
- Ejects through Aortic Semilunar Valve
- Into the Aorta and Coronary Arteries
What are Chordae Tendinae?
Tendon-like cords on the cusps of the AV Valves
What is the function of Papillary Muscles?
Prevents valves from opening in opposite direction
Explain the opening and closing of the Atrioventricular Valves (Tricuspid and Bicuspid Valves).
- Blood flow into the Atriums causes pressure which opens the AV Valves into the Ventricles.
- AV Valves closes when ventricles contract
Explain the function of the Pulmonary/Aortic Semilunar Valves.
- Ventricles contract opening the Pulmonary and Aortic Valves into the Arteries
- Once ventricles relax, left over blood will flow into the cusps of the semilunar valves
What is the "Lub" sound from the Heart?
Sound of AV Valves closing
What is the "Dub" sound from the Heart?
Sound of Semilunar Valves closing
Explain the Pulmonary Circulation Pathways.
- 'Right side of the Heart'
- Deoxygenated blood enter Right Atrium
- Pumped into Right Ventricle
- Up into the Pulmonary Arteries (Lungs)
- Deoxygenated blood rid CO2 for O2 in Lungs
- Oxygenated blood from Lungs enter the Left Atrium via 4 Pulmonary Veins
Explain the Systemic Circulation Pathways.
- 'Left side of the Heart'
- Oxygenated blood enter Left Atrium from Lungs
- Pumped into Left Ventricle
- Up into Aorta and out to body tissues
- Tissues use O2 and releases CO2 making it deoxygenated, which eventually goes in Right Atrium
Describe Coronary Circulation.
Heart provides own circulation, with coronary arteries encircling the Heart, and receiving blood supply in between beats
Describe Autorhythmic Fibres?
Self-excitable cardiac muscle cells generating own APs
- Sets rhythm of APs for contactions
- Form a conducting system
Explain the Conducting System of the Heart.
A pathway at which APs progress through the heart
List the sequence of an AP through the Heart (Conduction System).
SA Node (Sinoatrial Node)
AV Node (Atrioventricular Node)
B. of His
Describe the Sinoatrial Node (SA Node).
Repeatedly generates APs causing atrial contraction and ejection of blood into the AV node
Describe Atrioventricular Node (AV Node).
Causes ventricular contraction and ejection of blood into the arteries
Define Cardiac Cycle
All events associated in one heart beat
Define Heart Rate and average HR.
- Heart beats in 1 min
- Avg. HR 72bpm
Define Strike Volume and average SV
- Blood ejected from each ventricle with each beat
- Avg. SV 70mL
Define Cardiac Output and average CO.
- Heart rate x Stroke Volume
Define Cardiac Output.
Amount of blood ejects per minute
What are the factors that regulate HR?
Other Factors (age/sex/fitness/body temp.)
The control centre in the _______________ gets input from sensory receptors and high brain centres to regulate HR.
An increased SyNS, will __________ HR
An increased PaNS, will __________ HR
Which Hormones/Ions increase HR and contractility?
Which Hormones/Ions is needed for normal APs, and elevate blood levels and decrease HR?
Sodium and Potassium
What 3 factors help maintain equal stroke volume?
Define the Frank-Starling Law.
Degree of stretch = Greater contraction
Define the Preload factor that helps maintain equal stroke volume.
Amount of stretch equals to volume of blood that fills the ventricles at the end of diastole (end diastolic volume)
Define the Contractility factor that helps maintain equal stroke volume.
Strength of contraction at given Preload