Organization of the Thorax and Overview of Cardiovascular System Flashcards
What are 3 cavities of the thorax?
Right pleural cavity
Left Pleural cavity
Mediastinum
What are the boundaries of the mediastinum?
Superior: Superior thoracic aperture
Inferior: Inferior thoracic aperture (diapragm)
Anterior: Sternum
Posterior: Thoracic vertebrae
Lateral: Pleura
A line running from the sternal angle to ________ divides the mediasinum into superior and inferior divisions.
T4-5
The ______________ further divides the inferior mediastinum into the anterior and posterior mediastinum.
Pericardial sac
What are the contents of the superior mediastinum?
Arch of Aorta
- Brachiocephalic artery
- Left Common carotid artery
- Left Subclavian artery
Superior Vena Cava
- Brachiocephalic veins
- Left superior intercostal vein
- Supreme intercostal vein
- Azygos vein
Vagus Nerve
- Right vagus nerve
- Left vagus nerve
Phrenic nerve
Thymus
Trachea
Where is the thymus located in a child?
Immediately beneath the sternum
NOTE: In the adult, the thymus usually undergoes involution to fat.
Within the superior mediastinum, the left brachiocephalic vein crosses and joins the right to form the ___________.
Superior vena cava
NOTE: The distal part of the superior vena cava is in the middle mediastinum
What are the branches of the arch of the aorta?
Brachiocephalic trunk
Left common carotid
Left subclavian
The _________ connects the aortic arch and left pulmonary artery.
Ligamentum arteriosum
What condition can be a sign of aortic aneurysm? Why?
Dysphonia
*This is becuase the left recurrent laryngeal neve passes posterior to the ligamentum arteriosum. Aortic aneurysm can cause compression onto the left recurrent laryngeal artery.
What is the course of the right laryngeal nerve?
Loops under the right subclavian artery then traveling upwards.
What is the course of the left recurrent laryngeal nerve?
loops under the aortic arch
Why do the left and right recurrent laryngeal nerves have different courses in the adult?
Because of the differntial development of the right and left 4th aortic arches
Are the bronchi in the mediastinum?
No because the trachea bifurcates at the sternal angle
Biopses of carinal nodes are done to test for what disease?
Lung cancer metastases
The esophagus is found directly posterior to which structure?
Trachea
The azygos vein terminates into the ______________.
Superior vena cava
Where does the azygos vein begin?
At the abdomen
Label
Label
Label
The anerior mediastinum is sandwhiched between the body of the __________ and the __________.
Sternum; pericardial sac
What are the contents of the anterior mediastinum?
Internal thoracic artery and vein
Transversus thoracis
The __________ forms the border of the middle mediastinum.
Pericardial sac
NOTE: The phrenic nerve is runing in the pericardial sac
The phrenic nerve provides __________ (sensory/motor) innervation to the pericardium.
Sensory
From which spinal nerves does the phrenic nerve originate? What is the clinical significance of this?
The phrenic nerve originates from spine nerves C3, C4, and C5 and because of this irritation of the pericardium produces referred pain in the shoulders.
What are the contents of the middle mediastinum?
Heart
Ascending aorta
Pulmonary trunk (proximal)
Superior vena cava (termination)
Label
An enlarged left atrium will displace the ____________.
Esophagus
Where is the posterior mediastinum found?
Between the pericardial sac and the vertebral column
What are the contents of the posterior mediastinum?
Descending aorta
Esophagus
Esophageal plexus (right and left CN X)
Thoracic duct
Azygos vein
Where does the descending aorta exit the thorax?
Through the aortic hiatus in the diaphragm at T12
What are the branches of the descending aorta?
Bronchial
Posterior intercostal
Esophegeal
The esophagus has 4 constrictions. What is the clinical signifance of this?
When passing instruments into the stomach, these four constrictions are potential sites where the esophagus may be perforated
What is the course of the esophagus?
- Begins in the neck at C6
- Cross the arch of the aorta
- Is crossed by the left bronchus
- Exits the thorax at esophageal hiatus in the diphragm at T10
What are the four esophageal constrictions?
- At the start of the esophagus, where the laryngopharynx joins the esophagus, behind the cricoid cartilage
- Where it is crossed on the front by the aortic arch in the superior mediastinum
- Where the esophagus is compressed by the left main bronchus in the posterior mediastinum
- The esophageal hiatus where it passes through the diaphragm in the posterior mediastinum
As the esophagus pierces the diaphragm and enters the abdomen, the esophageal plexus forms two nerves:
- Anterior (left CN X) gastric nerve
- Posterior (right CN X) gastric nerve
The greater splanchnic nerve traverses which vertebral bodies?
T5-9
Label
Where does the thoracic duct terminate?
At the junction of the left subclavian and internal jugular veins
The ______ is the largest lymph vessel in the body.
Thoracic duct
Where does the thoracic duct begin?
In the abdomen (at the cisterna chyli)
What two structures does the throacic duct run between?
Aorta (descending aorta)
Azygos vein
What are the top 2 global causes of death?
Ischemic heart disease
Stroke
The heart, vessels, and blood develop from which embryonic layer?
Mesoderm
NOTE: This is the first system to function at day 25 when the heart 1st begins to beat
Mechanical obstruction of blood supply.
Ischemia
decreased levels of O2 .
Hypoxia
No O2
Anoxia
An area of necrosis resulting from inadequate blood flow.
Infarct
The pulmonary loop supplies the ________ in the lungs.
Alveoli
The heart is a dual pump. The ______ (left/right) side of heart pumps blood through the pulmonary loop. The __________ (left/right) side of the heart pumps blood through the systemic loop.
Right; left
How is cardiac output measured?
The product of the heart rate and the stroke volume
What is the stroke volume?
The volume of blood pumped from the ventricle per beat
Besides the heart, what other mechanism can be used for pumping blood?
Contraction of the diaphragm pumps blood in the right atrium by:
- Decreasing thoracic pressure
- Increasing abdominal pressure
- Opening up the IVC
What physiological facts affect flow?
Pressure (directly proportional)
Resistance (indirectly proportional)
How is resistance related to radius?
A decrease in radius, increases resistance
Resistance= 1/r4
Resistance is largely the result of ____________ between blood and the walls of blood vessels.
Friction
Atherosclerosis
Hardening and narrowing arteries
*Atherosclerosis increases resistance and flow turbulence
Diminished pulse can be a sign of ________ disease.
Vascular
To offset a 16 fold increase in resistance, pressure must be increased by __________ times.
16
*This means that the heart must work harder
An ___________ results when the pressure in a vessel exceeds the elastic components of the tunics.
Aneurysm
Function of capillaries
- Connect arteries and veins
- Site where gases, nutrients, and wastes are exchanged between blood and tissues
Moving distally from the heart, ____________(arteries/veins) get progressively smaller.
Arteries
- Conduction arteries
- Distribution arteries
- Arterioles
NOTE: Capillaries are the diameter of a single RBC
What characteristics do arteries take on as they travel to their targets?
- More numerous
- Smaller in diameter and cross sectional area
- Higher in resistance
- Thinner- walled
*The opposite occurs in veins
What are the three coats of blood vessels?
- Tunica intima
- Tunica media
- Tunica externa
What differentiates the tunica media from the two other coats of blood vessels?
Tunica media is made up of smooth muscle and connective tissue fibers and it is elastic.
NOTE: Contraction of smooth muscles controls lumen diameter and blood flow
What are the characteristics of each coat of blood vessels?
-
Tunica intima
a. endothelia cells
b. loose connective tissue -
Tunica media
a. smooth muscles*
b. elastic & connective tissue fibers -
Tunica externa (adventitia)
a. loose connective tissue (like epineureum)
i large, conducting arteries, the tunica media is mostly _________.
Elastic fiber
Elastic arteries ___________ (expand/recoil) during systole.
Expands
*This dampens the pulse surge
NOTE: Systole is when the heart contracts and pumps blood into the arteries
Elastic arteries __________ (expand/ recoil) during diastole.
Recoil
*This propels the pulse forward and conserves energy
NOTE: During diastole, the heart muscles relax and allows the chambers to be filled with blood
Conduction arteries are __________ (elastic/muscular), while distribution arteries are (elastic/ muscular).
Elastic; muscular
In smaller, distribution arteries, the tunica media is mostly __________.
Smooth muscle
NOTE: Contraction of muscles in distribution arteries controls blood flow to a particular muscle, gland, organ, etc.
As blood flows from the heart, blood pressure _______.
Decreases
*The largest drop is in the arterioles.
Most peripheral resistance occurs in __________.
Arterioles
NOTE: The resistance of a maximally constricted arteriole is 80 times that of a fully dilated arteriole
____________ innervate the smooth muscle around blood vessels.
Perivascular nerves
*Innervation is usualy sympathetic vasoconstriction
Raynaud’s Disease
Excessive sympathetic tone in arteries supplying the limbs, causing the digits to be cyanotic and cold.
Fluid exchanges occur mostly at ______ where there is a net flow of serum to the interstitial fluid.
Capillaries
Arteries and veins run in pairs. What is the exception?
Skin
NOTE: Arteries and veins running in pairs allows for counter-current heat exchange
Compare veins and arteries.
- Veins have larger diameters
- Veins have thinner walls
- Veins are more compliant (or less resilient)
Hypertension produces _____ (thinner/thicker) walled vessels over time.
Thicker
In increase in the thickness of a blood vessel _________ (increases/decreases) compliance.
Decreases
*This can exasperate the problems of hypertension
___________ (veins/arteries) have more blood volume.
Veins
*Approximately 64% of blood is found in veins
The distribution of blood in different organs changes according to activity. During exercise, what happens to blood flow in the muscles, abdomen, and brain respectively?
Muscles: increases
Abdomen: Decreases
Brain: No change
___________ capillaries take up the interstitial fluid and return it to the cardiovascular system.
Lymphatic
Plasma leaks out of the capillaries to form ____________.
Interstital fluid
How do blood capillaries and lymph capillaries differ?
Lymph capillaries begin as cul-de-sac
Ascites
the accumulation of protein-containing (ascitic) fluid within the abdomen
*Can result from capillary output being greater than lymphatic uptake
Which diseases or conditions can result from greater capillary output than lymphatic uptake?
Tissue edema
Ascites
Capillaries surround which part of the pulmonary system?
Alveoli
Interstitial fluid leaks into the alveoli producing _________.
Hypoxia
*This is the final pathway of cogestive heart failure
In a ________ system, a blood cell passes through two capillary beds in series before returning to the heart.
Portal
What are the 3 portal systems in the body?
Hepatic
Hypophyseal
Renal
