Lab Practical Flashcards
What type of tissue comprises the heart valves?
Fibroelastic tissue
Dense Connective tissue
Outer is lined by endothelial cells
List 5 characteristics of Myocardium
- Cardiomyocytes with centrally located nuclei
- Intercalated discs
- Striations
- Branching patterns
- Capillary pattern with simple squamous epithelium
The visceral pericardium is AKA
Epicardium
Where is mesothelium found?
On the visceral pericardium (epicardium) that secretes lubricants
Describe 3 characteristics of visceral pericardium
- Dense fibrocollagenous tissue
- Coronary Blood vessels & nerves
- Adipose tissue
What layer are the heart tissue are Purkinje fibers found?
Endocardium
What layer is thickest in the aorta?
Tunica media because it has a lot of smooth muscle and multiple layers of elastic laminated organized in a concentric fashion
Where are vasa vasorum found?
- the Tunica Adventitia of blood vessels
- Vasa vasorum: provide oxygen and nutrients for large vessel walls
Aside from Smooth muscle, what else is found in the tunica media
- Elastic fibers
- Reticular fibers
- Proteoglycans
- Elastic fiber plates: with fenestrations for diffusion of nutrients
Describe the tunica adventitia of blood vessels
- Loose elastic and collagen fibers
- Fibroblasts & macrophages
- Vasovasorum
- Nervivascularis
Describe the layers of the muscular arteries
Outermost: Tunica adventitia
External elastic laminate
Tunica media
Internal elastic lamina
Tunica intima
Describe the cellular layers of arterioles
- Tunica adventitia: thin
- Tunica media: 1-2 smooth muscle layers
- Tunica intima: absent?
Describe the cellular layers of venules
Outermost: Tunica adventitia-thin
Tunica media: little to none
Tunica intima: simple squamous & basal lamina endothelium
What blood vessels are the primary sites involved in inflammatory response?
Venules by allowing leukocytes to migrate to affected tissue
What surrounds capillaries?
Pericytes
Describe the cellular layers of capillaries
- Single layer of flattened endothelial cells lines the capillary lumen
- Tunica media and adventitia are often absent
Define silent mutation
Occur when a base pair change in a coding region does not affect the amino acid that is encoded
Ex. UCG to UGU is silent because both are codons for cystine
- Can also occur when comparing mutation occurring in a non-coding vs coding region
Define Missense mutation
The new codon causes insertion of incorrect amino acid into a protein. Genome length does not change
The protein function depends on the new amino acid
Define nonsense mutation:
- The new codon causes the protein to prematurely terminated
- Product is shortened and non function
When do nonsense mutations occur?
- When the base pair change in a coding region results in the creation of a stop codon
- Proteins will be truncated as a result of this type of mutation
- Ex. UGG to UGA in β thalassemia or GGA to UGA in cystic fibrosis
Give an example of mutation causing transcription factor changes leading to congenital deafness or limb abnormalities
- Mutation in Pax 3 leading to Klein Waardenburg syndrome
What is PAX 3?
Gene encodes a transcription factor that regulates the expression of genes that impact cell proliferation, survival, differentiation, and motility
- Directs the activity of other genes that signal neural crest cells to form specialized tissues and cell types
β thalassemia can occur by 2 genetic mutation mechanisms:
1.
2.
- Nonsense mutation where the STOP codon appears early leading to a truncated protein
- Mutation in splice site that causes defects in HBB gene coding for β globulin
Tay-Sach disease is related to problems with _____________________. Its genetic mutation is related to _______________ _____________ involving the HEXA gene
Tay-Sachs disease is related to problems with sphingolipids. Its genetic mutation is related to mutation in splice sites involving the HEXA gene
Trinucleotide Repeat Expansion: Mutations occurring ___________________ _______ __________
Fragile X syndrome (FXS):
Myotonic dystrophy (MD):
- Trinucleotide repeat expansion with repeats occurring in untranslated region of gene
- FXS: mutations occurring in 5’ UTR of FMR1 gene
- DM: mutations occuring in 3’ UTR of DMPK gene
Expansion of trinucleotide repeats: Mutations occurring __________ _________________
- Huntington’s Disease:
- Spinobulbar muscular atrophy (SBMA):
- Mutations occurring in coding region
- HD: HTT gene repeats
- SBMA: AR gene repeats
What is hypomorph?
- Loss of function mutation that causes either reduced activity or decreased stability of the gene product
What is amorph?
- Type of loss of function mutation
- AKA Null allele
- Complete loss of gene product
Where are sinusoidal capillaries found?
- Wide leaky capillaries
- Found in liver, spleen, bone marrow
Where do aneurysms tend to form?
Form at branch points
Where do are lipid deposits in atherosclerosis?
- Microphages phagocytose lipids and other material and become bloated and appear as “foam cells”
- Tunica media pushes tunica intima & creates blockage within the vessel
When might AV shunts be activated to keep blood from entering capillaries?
- To pull blood away from the skin, maintain heat from example
What changes in blood metabolites will increase blood flow, for example in exercising muscles
- Increase H+, Increased CO2, K+ increase
- Decrease O2 will cause vasodilation
What substances diffuse directly through cell membrane of capillaries?
Lipid soluble like CO2 or O2
What substances use intercellular clefts of capillaries to cross into interstitial fluid?
Lipid insoluble substances such as H2O, Na+, Cl-, glucose
When does lymph flow reach a maximum?
Lymph flow reaches a maximum when the interstitial pressure (P t ) rises slightly above the atm
Microcirculation in the muscles is affected due to:
Impaired arteriolar autoregulation
How does PAD contribute to ischemia and pain?
Atherosclerosis limits blood flow through the larger arteries, and the ability of arterioles to dilate in response to increase metabolic demands is compromised
- Intermittent claudication
What is the main protein that contributes to plasma colloid osmotic pressure?
Albumin which is made in the liver
Which has greater alteration of filtration: changes to venous resistance or arteriolar resistance?
Venous resistance has greater effect
In persons with nephrotic kidney disease, what filtration mechanism will be changed?
Capillary oncotic pressure will be decreased due to decreased circulating plasma proteins
In persons with heart failure, what filtration mechanism will be changed?
Increased capillary hydrostatic pressure via increased RAAS activation to try and increase cardiac output will increase blood volume
Aside from liver failure and kidney nephrosis, what might decrease circulating plasma proteins?
Severe burns
How does Atrial naturetic peptide exert its effects on fluid balance?
- Regulates fluid, sodium & K+ levels
- Increases glomerular filtration rate
- Inhibits ADH
- Inhibits renin secretion
- Decreases capillary hydrostatic pressure
What is hyperemia?
Increased amount of blood in the vessels of an organ or tissue in the body
What is active hyperemia?
Increased metabolic activity means more metabolites which causes dilation of vessels and more flow
What does adenosine do?
Causes vasodilation
What is reactive hyperemia?
- Found in MI
- During Transient ischemia metabolites build up. Body responds with excess blood flow requiring to was the metabolites after the occlusion is removed
What are the mechanisms that incur reactive hyperemia?
- Inc. vasodilatory substances: Adenosine, CO2, adenosine phosphate compounds, histamine, potassium ions and H+ ions
- By lack of oxygen which could cause opening of more precapillary sphincters in the affected tissue and force blood through the capillary
What happens to re-perfusion after a block in coronary blood flow?
During coronary artery occlusion, the area of the heart supplied by the artery is deprived of its blood flow
Upon reperfusion there is a dramatic rise in coronary blood flow, far above the baseline flow prior to the occlusion
Define autoregulation of blood flow
Ability of a tissue to maintain blood flow relatively constantly over a wide range of arterial pressure
What are acute responses to heart failure?
Increase HR & contractility Increase mean systemic filling pressure and venous return
Maximally activated within 30-60 seconds
Describe how Left sided cardiac failure leads to Right sided heart failure
- L heart failure = decreased CO & increased afterload
- The blood starts to back up into the lungs and subsequently increase R atrial pressure
- Damming of blood into the R atrium will increase pressure in the R atrium and lead to decreased venous return
Which is a stronger indicator of heart failure, ANP or BNP?
BNP because it comes from the ventricles
- Both are diuretics
Describe how Berberi causes heart failure
- Thymine (B1) deficiency indicates unmet metabolic needs in peripheral tissues, will cause peripheral vasodilation and low TPR.
- Increased CO despite the weakened heart due to Vit B deficiency further contributing to heart failure
- Seen in alcoholism and malnutrition
What arterio-venous fistula?
Opening between a large artery and vein. Blood bypasses resistance beds and results in low TPR. Because TPR is low, CO must increase to maintain blood pressure and meet metabolic demands
How does hypoxia vary in blood perfusion of the body vs. the lungs? Why?
- In the body will result in vasodilation
- In the lungs will incur vasoconstriction
- This will increase pulmonary vascular resistance to enhance blood flow to areas of the body in need and decrease flow of blood to the lungs
What does increased renal blood flow in the afferent arteriole do?
Increased RBF will increase the hydrostatic pressure in the glomerular capillaries to increase the glomerular filtration rate and subsequently lowering retention of fluid
What does decreased renal blood flow in the afferent arteriole do?
Decreased RBF will decrease the hydrostatic pressure in the glomerular capillaries to decrease GFR
What does renal efferent arteriole constriction do?
- Increasing constriction will increase the hydrostatic pressure in the glomerular capillaries to increase glomerular filtration and decrease renal blood flow
What does renal efferent arteriole dilation do?
Decreased hydrostatic pressure in the glomerular capillaries will decrease GFR but increase renal blood flow
Where are macula densa cells?
In distal tubules of kidneys
How might the macula densa cells respond to increased NaCl in the tubules?
- Inc. NaCl means increased GFR
- Initiates the secretion of adenosine for vasoconstriction in the renal tubules only (everywhere else it causes vasodilatation)
What are the parameters of EKG indicating hyperkalemia?
- Prolonged PR internal
- Widened QRS
- Flattened P wave
Why does hyperkalemia cause slowed heart rate?
Increased resting membrane potential BUT this rise in RMP will inactive Na+ channels so that they cannot depolarize the SA node
- Then not able to let Na+ channel inactivation to reactivate and be ready for contraction again
What are the drawbacks to CT?
- Poor soft tissue contrast
- Ionizing radiation
- Acute contrast nephropathy b/c contrast is viscous
How are heart murmurs graded?
Scale of 1-6
1. Very faint, only heard after listener has “tuned in” & may not be heard in all positions
2. Quiet but heard immediately
3. Moderately loud
4. Loud with palpable thrill
5. Very loud, with thill & may be heard with stethoscope partly off the chest
6. Very low with thill and can be heard without stethoscope
What is pericardial knock?
- High pitched sound, best heard in diastole
- Caused by thick pericardium limiting expansion of the ventricle
What is ejection click?
High pitched sound after S1 associated with dilated pulmonary artery or septal defect
When listening to heart sounds, what are you assessing?
- Frequency/pitch
- Intensity
- Duration
- Pathology
What sound might a S3 make?
“Kentucky” as blood falls from atrium to ventricle
What sound might S4 make?
“Tennessee” due to forceful contraction to compensate for abnormally stiff ventricle
How do you document pulses?
Rate-BPM
Rhythm: regular/irregular
Symmetry: equal on L & R side
Amplitude: strength of each beat
Describe the system of amplitude for documenting pulses
0: Absent
1: Weak
2: Normal
3: Increased/Strong
4: Bounding
What are janeway lesions?
- Small, non-tender erythematous or hemorrhagic macular or nodular lesions on palms/soles of feet
- Due to neutrophilic infiltration of capillaries
What are Osler nodes?
- Painful red, raised lesions on hands and feet due to microthrombi that lead to localized immune mediated vasculitis
What is Xanthelasma?
- Yellow plaques occurring most commonly near the inner canthus of the eye lid
- Deposits of cholesterol under the skin
- Can be indicative of plagues in the vessels as well
