Unit 12: Cardiovascular system (heart and circulatory routes) Flashcards
(17 cards)
What does the cardiovascular system include and do?
Includes: heart, blood vessels, blood
Does: transports gases, nutrients, hormones, wastes, heat
Also for: protection against disease, fluid loss (clotting)
Where is the heart located and what does it do?
Located in a cavity called the mediastinum (= space between lungs w/in thoracic cavity).
Heart = pump - blood enters AND exits from the superior section.
What is the covering of the heart and what are its parts?
Covering = pericardium = double-walled sac surrounding heart.
3 layers:
a) fibrous pericardium
- = outermost layer = dense irregular CT (b/c want it to be strong in every direction)
- anchors to surrounding structures (like diaphragm, great
vessels - aorta, vena cava, etc.)
b) serous pericardium is composed of:
i. parietal pericardium (2 layers - epithelial and connective) - connected to fibrous pericardium, includes PERICARDIAL
SAC
ii. visceral pericardium (= epicardium) (2 layers - epithelial
and connective)
- fused to heart surface, so is part of heart wall
Between pericardial layers = pericardial cavity w/ serous fluid (lubricates).
What are the 3 parts of the heart wall?
a) epicardium (= visceral pericardium)
- simple squamous epithelium and CT
b) myocardium (= cardiac muscle)
- arranged in spiral/circular pattern, reinforced w/ CT
c) endocardium
- simple squamous epithelium and CT
- epithelium named endothelium (NOT a tissue type - just
name of the layer) - lines INNER SURFACE of heart and ALL
blood vessels
What are the four chamber of the heart and the associated blood vessels?
a) Right Atrium (top)
- 3 major veins connected to RA that carry deoxygenated
blood into the chamber:
i. inferior vena cava (carries blood from body below heart)
ii. superior vena cava (carries blood from body above
heart)
iii. coronary sinus (carries blood from the myocardium)
b) Left Atrium (top)
- 4 veins carry oxygenated blood into left atrium from the lungs:
i. left pulmonary veins
ii. right pulmonary veins
c) Right Ventricle (bottom)
- 1 artery, the pulmonary trunk exits the right ventricle and
then divides to form 2 pulmonary arteries (left and right).
These carry deoxygenated blood towards the lungs.
d) Left Ventricle (bottom)
- 1 artery, the aorta, exits the LV and carries oxygenated
blood to all organ system - much thicker than RV
What are the septa of the heart?
Septa = separate chambers
a) Interatrial septum - separates atria
b) Interventricular septum - separates ventricles
What is the cardiac (fibrous) skeleton?
- fibrous CT separating atria and ventricles
- provides firm attachment point for cardiac muscles
- forms solid rings around heart valves, base of aorta and pulmonary trunk that provide structural support for these structures and hold them in place
- provides electrical insulation - prevents simultaneous contraction of atria and ventricles
What are the valves of the heart?
Valves = for one way flow of blood
a) Atrioventricular (AV) valves:
i. BIcuspid (mitral) valve (very thin - almost translucent)
- btw. LA and LV - has 2 sheet-like cusps made of CT
ii. TRIcuspid valve - btw. RA and RV (it’s always RIGHT to
TRI) - has 3 sheet-like cusps made of CT
- Chordae tendineae (strings of CT) that attach atrioventricular valve cusps to papillary muscles that project from the ventricular myocardium - they prevent eversion of cusps
b) Semilunar valves = 3 cup-like cusps each
i. aortic (separates LV and aorta)
ii. pulmonary (separates RV and pulmonary trunk)
What are the two types of cardiac muscle cells?
Contractile cells and conduction system cells
Info on contractile cells
- Forms majority of myocardium
- Similarities to skeletal muscle:
i. striated (myofibrils w/ sarcomeres)
ii. has sarcoplasmic reticulum and T-tubules - Differences:
i. branched (myofibrils w/ sarcomeres)
ii. uninucleated (single nucleus)
iii. intercalated discs = region where 2 fibers meet
iv. contain anchoring and gap junctions
Info on conduction system cells
- Forms remainder of the myocardium
- Cardiac muscle cells that are modified to produce AND conduct electrical impulses - DO NOT CONTRACT
- Have many gap junctions that help electrical signals to spread very quickly
- Parts:
i. sinoatrial (SA) node
- in RA at base of superior vena cava
- generates impulses the fastest - sets pace
ii. atrioventricular (AV) node
- base of RA
iii. Atrioventricular Bundle (Bundle of His)
- superior part of interventricular septum
- electrically connects atria to ventricles
iv. Atrioventricular (AV) Bundle Branches
- carry impulse to apex (bottom tip) of heart
v. Purkinje fibers
- terminal fibers in ventricles (not found in atria) that
carry signals from apex upward to all parts of the
ventricle
- NOTE: electrical signal spreads from conduction system
to contractile cardiac cells then they contract
What is the circulatory route?
Closed, double circulation route.
- closed = blood confined to heart and blood vessels
- double = 2 routes (pulmonary and systemic)
Info on adult pulmonary circulation
Pulmonary circulation = TO LUNGS for oxygenation of the blood.
- carries blood from RV to lungs via pulmonary arteries (deoxygenated blood)
- picks up oxygen in lungs via capillaries
- carries blood from lungs to LA via pulmonary veins (oxygenated blood)
Info on adult systemic circulation
Systemic circulation = for delivery of oxygenated blood to all other tissues (rest of body).
- carries blood from LV to organs via aorta (oxygenated)
- organs take up oxygen from blood via capillaries
- carries blood from organs to RA via superior and inferior vena cava (deoxygenated)
- overall route: LV to RA = SYSTEMIC CIRCULATION
- subdivisions include routes to individual organs/organ systems, for example:
- cerebral = brain
- hepatic = liver
- coronary = heart
- bronchial = parts of respiratory system
- etc.
Info on coronary circulation (see flow chart in notes - pg. 5)
LV to aorta, and then aorta two routes to R and L coronary arteries.
Info on fetal circulation
- oxygen demand for fetus is lower than is for adults
- fetus gets oxygen (02) and nutrients from and expels wastes to mother’s blood
- exchange site in the placenta
- blood supplies in close together, BUT DO NOT MIX - the
blood vessels ARE NOT attached)
- blood supplies in close together, BUT DO NOT MIX - the
- differences from adult circulation:
a) umbilical vein (toward the fetal heart) - carries
oxygenated blood from placenta to vena cava
b) lungs and liver are late to develop and their functions
are handled by the maternal organs - 3 shunts allow most blood to bypass these organs (minimal blood flow to these organs for nourishment/growth) - see next card
What are the 3 shunts in fetal circulation?
i. ductus venosus
- connects umbilical vein (oxygenated blood) to inferior vena cava (deoxygenated blood)
- permits most of oxygenated blood coming from placenta to bypass the liver capillaries
- oxygenated and deoxygenated blood mixes in inferior vena cava and enters fetal RA
ii. foramen ovale
- hole in interatrial septum
- allow blood to move from R to L atrium
- bypasses the uninflated fetal lung (fetus is not breathing, so no gas exchange takes place here)
iii. ductus arteriosus
- connects pulmonary trunk and aorta
- bypasses the uninflated fetal lung (fetus is not breathing, so no gas exchange takes place here)
- following birth all shunts normally become closed
- umbilical arteries (away from fetal heart) return mixed blood to the placenta
