Chambers and Valves

• Ventricular Septum has two portions:
  1. Muscular and
  2. Membranous.
  
  
• Ventricular septal defect, the most common congenital abnormality of heart, usually involves the membranous portion.
  
  
• Fossa ovalis, which is an embryological remnant of foramen ovale, if remain patent would result in atrial septal defect.
  
  
• Sinus venarum is the smooth posterior wall of the right atrium.
  
  
• Pectinate muscle is the trabeculated muscle on internal surface of right atrium.
  
  
• Four valves in total:
  1. Tricuspid (right AV) valve
  2. Mitral (left AV) valve
  3. Pulmonic valve (right ventricle)
  4. Aortic valve (left ventricle)
  
  
• Valves are made up of thin sheets of fibrous tissues called cusps.
  1. Mitral valve has two cusps (anterior and posterior)
  2. Tricuspid valve has three cusps (anterior, posterior, and septal)
  3. Pulmonic valve has three cusps (right, left, and anterior)
  4. Aortic valve has three cusps (right, left, and posterior)
  
  
• Each cusp is attached to two papillary muscles. The papillary muscles are themselves connected to the cusps via chordae tendineae.
  
  
• The right atrium receives blood from Superior Vena Cava, Inferior Vena Cava and coronary sinus → blood flows through the tricuspid valve into the right ventricle → blood flows into pulmonary artery via pulmonic valve → capillary beds of lungs → pulmonary veins into the left atrium → passes through mitral valve into left ventricle → passes through aortic valve into the aorta.
  

Source:
BSc School C Level 2a Module 6
Cardiovascular Mechanics
Notes for Cardiovascular Fluid Mechanics
K.H. Parker

Know your “Little Brain” well - Cerebellum

The cerebellum is Latin for little brain. It is responsible for:

• Postural control
• Muscle tone
• Repeated motor functionality
• Coordination of voluntary movements
  

Therefore, if a disease affects the cerebellum, it would result in deterioration of:

• Gait
• Balance
• Coordinated movement

However, no paralysis or inability to start or stop the movement would occur.


Layers from outer to inner:

Three in numbers

1. Molecular
2. Purkinje
3. Granule Cell

Major Pathway:

Purkinje cells → deep cerebellar nucleus; dentate nucleus → contralateral ventral lateral nucleus → Primary motor cortex → pontine nuclei → contralateral cerebellar cortex


Input:

• Inferior olivary nucleus of medulla via Climbing fibers
• Vestibular nucleus, spinal cord, pons via Mossy fibers
• Most inputs via Inferior cerebellar peduncle and Middle cerebellar peduncle

Output:

• From deep cerebellar nucleus (fastigial, interpositus, dentate)
• Most outputs via Superior cerebellar peduncle

Disorders:

• Hemisphere lesions would produce ipsilateral findings such as intentional tremors, dysmetria (lack of coordination of movement), dysdiadochokinesia, scanning dysarthria, nystagmus, hypotonia
• Vermal lesions would produce truncal ataxia

Source: The University of Western Ontario

Ouch! that hurts - Acute Inflammation - Q&As - Series 1

Question 1: The cardinal sign(s) of acute inflammation is/are the following:
a. Rubor (Redness)
b. Calor (heat)
c. Tumor (Swelling)
d. Dolor (Pain)
e. All of the above

Answer: It is option (e) All of the above. All of them are the cardinal signs of acute inflammation.

One should be familiar with the Triple response to injury or Triple response of Lewis. Any transient injury would lead to an initial transient vasoconstriction forming a thin red line. This would be followed by vasodilation causing flare and finally, a localized exudation of fluid would form, otherwise known as wheal.


Question 2: In the following type of inflammation, dead neutrophils, bacteria, and necrotic tissues in the form of a turbid consistency can be seen as a focal cluster:
a. Cellulitis
b. Abscess
c. Catarrhal
d. Granulomatous
e. Hemorrhagic

Answer: It is option (b) Abscess. Cellulitis and catarrhal inflammation may produce similar features but an abscess is distinctive in that it is found in a localized cluster and is encapsulated. Granulomatous is a dry cellular proliferation of fibroblasts, and epithelioid cells. Hemorrhagic is a severe inflammatory exudate associated with capillaries damage and hemorrhage of red blood cells.


Question 3: A fluid obtained from the peritoneal cavity is turbid in nature, yellow in color, contains fibrinogen, clots rapidly, and has high specific gravity. You most likely suspect this fluid to be:
a. Transudate due to high portal vein pressure
b. Transudate due to right heart failure
c. Liver disease resulting in protein loss
d. Exudates due to peritoneal inflammation

Answer 3: It is option (d) Exudates as a result of inflammation. Transudate is an effusion, which has low protein content, low specific gravity, very low cellular count and no coagulation. Transudate results due to changes in hydrostatic and oncotic pressures across the vessels whereas exudate is a result of changes in vascular permeability. Protein loss due to any liver disease would result in low intravascular oncotic pressure that would lead to the formation of a transudate, not an exudate.

Tumor Markers

1. CEA: Any tumor which is derived from gut such as colonic, pancreatic etc...
   
   
2. AFP:
   Hepatocellular carcinoma
   Embryonal cell tumor of testes
   Malignant teratoma
   
   
3. CA-125: Ovarian carcinoma
   
   
4. B-HCG:
   Choriocarcinoma
   Hydatiform mole
   Germinoma
   
   
5. PSA: Prostatic carcinoma
   
   
6. Bombesin:
   Neuroblastoma
   Small cell carcinoma
   Gastric Carcinoma
   Pancreatic carcinoma
   
   
7. S-100:
   Melanoma
   Neural tumors
   Astrocytomas
   
   
8. CA 15-3:
   Benign breast disease
   Breast carcinoma
   
   
9. CA 19-9:
   Pancreatic carcinoma
   Colorectal carcinoma
   
   
10. Placental alkaline phosphate:
    Seminoma
    Ovarian carcinoma
    Pregnancy
    
    
11. Neuron specific enolase: Small cell carcinoma of lung
    
    

Immunopharmacology - Questions and Answers - Series 1

Question 1: The following drug binds to FKBP-12 resulting in a complex that inhibits calcineurin.

1. Mycophenolate mofetil
2. Basiliximab
3. Azathioprine
4. Tacrolimus
5. Daclizumab

Answer: It is option (4) Tacrolimus. When Tacrolimus binds to FKBP-12, it forms a complex that inhibits calcineurin, a cytoplasmic phosphatase. Calcineurin is responsible for regulation of Nuclear Factor of Activated T cells (NFAT). NFAT translocates to the nucleus and increases the production of cytokines.

Question 2: The following is a chimeric anti-tumor necrosis factor-alpha monoclonal antibody:

1. Etanercept
2. Daclizumab
3. Infliximab
4. Tacrolimus
5. Basiliximab

Answer: It is option (3) Infliximab. It is a humanized MAb that is targeted towards TNF-alpha. Indicated in selected cases of rheumatoid arthritis and Crohn's disease. Etanercept is also targeted against TNF-alpha but it is not a monoclonal antibody. Instead, Etanercept is a chimeric protein which is a recombinant form of the human TNF receptor.

Question 3: The most effective pharmacological agent for immunosuppression of rejection of allografted kidney is the following:

1. Cyclosporine
2. Azathioprine
3. 5-FU
4. Cyclophosphamide
5. Vincristine

Answer: It is option (1) Cyclosporine. Cyclosporine is preferred due to its specific T-Cell inhibiting action. It also has very successful rate in protection against solid organ rejection.

Lung Volumes and Capacities

TLC	Total Lung Capacity	Lung volume during maximal inspiration
IC	Inspiratory Capacity	Volume inspired with a maximal inspiratory effort after passive expiration
FRC	Functional Residual Capacity	Volume left in the lung after passive expiration
VC	Vital Capacity	Volume expired from maximal inspiration to maximal expiration
RV	Residual Volume	Volume left in the lung after maximal forced expiration
IRV	Inspiratory Reserve Volume	Volume inspired with a maximal inspiratory effort in excess of tidal volume
VT	Tidal Volume	Normal breathing: air inspired and expired
ERV	Expiratory Reserve Volume	Volume expired beyond the passive expiration with active expiratory effort

TCA Cycle made simple

Citric Acid Cycle

• Also known as Tricarboxylic Acid Cycle (TCA Cycle) and Krebs Cycle
  
• Takes place in mitochondria
• Utilizes acetyl-CoA, which itself is generated from pyruvate by pyruvate dehydrogenase enzyme
• Each acetyl-CoA generates = 3 NADH, 1 FADH₂, and 1 GTP
• NADH and FADH₂ are responsible for delivering electrons to Electron Transport Chain to generate energy via oxidative phosphorylation.

Stoichiometric equation:
Acetyl-CoA + 3 NAD⁺ + FAD + GDP + P_i → 2 CO₂ + 3 NADH + 1 FADH₂ + 1 GTP + CoA

Regulatory Steps:

1. Citrate Synthase

• Inhibited by: ATP

2. Isocitrate dehydrogenase

• Rate-limiting enzyme
• Activated by: ADP
• Inhibited by: ATP, NADH

3. α-Ketoglutarate dehydrogenase

• Inhibited by: Succinyl-CoA, ATP, and NADH
  

Mnemonic:

1. "Can I Keep Selling Sex For Money, Officer?"

Citrate
Isocitrate
α-Ketoglutarate
Succinyl-CoA
Succinate
Fumarate
Malate
Oxaloacetate

2. "Our City Is Kept Safe And Sound From Malice"

Oxaloacetate
Citrate
Isocitrate
α-Ketoglutarate
Succinyl-CoA
Succinate
Fumarate
Malate

TCA Cycle connection to other pathways:

• Citrate → Fatty acid synthesis
• α-Ketoglutarate and oxaloacetate → Amino acid synthesis
• Succinyl-CoA → Heme synthesis
• Malate → Gluconeogenesis

Anatomy Simplified – Q&A – Series 2

Question 1: Which of the following structures can be found in the posterior mediastinum and empties into the Superior Vena Cava?

1. Brachiocephalic artery
2. Thoracic duct
3. Left brachiocephalic vein
4. Right brachiocephalic vein
5. Azygous vein

Answer: 5. Azygous Vein


Question 2: Which is not a component of posterior mediastinum?

1. Azygous vein
2. Esophagus
3. Trachea
4. Thoracic duct
5. Sympathetic trunk

Answer: 3. Trachea


Explanation:

Inferior mediastinum extends from sternum to anterior pericardium, trachea and great vessels. The inferior mediastinum can be divided further into three compartments:

• Anterior compartment
• Middle compartment
• Posterior compartment

Contents of Anterior Compartment:

• Thymus gland
• Lymph nodes
• Fatty tissue

Contents of Middle Compartment:

• Brachiocephalic vessels
• Pericardium and heart
• Pulmonary arteries and veins
• Ascending aorta
• Inferior and Superior vena cava
• Nerves and lymph nodes

Mnemonic: Blow to Pericardium causes PAIN
(Original mnemonic only at MedPrepOnline.Com)


Contents of Posterior Compartment:

Remember, there are five birds in the posterior mediastinum. They are:

1. Va-goose (Vagus nerves)
   
2. Esopha-goose (Esophagus)
   
3. Azy-goose (Azygos vein)
   
4. Hemiazy-goose (Hemiazygos vein)
   
5. Thoracic duck (Thoracic duct)

With the esophagus accompanies anterior and posterior esophageal plexuses
Splanchnic nerves are also present.


Most common masses found in each compartment listed above:

Anterior: Thymoma
Middle: Pericardial cyst
Posterior: Neurogenic tumours

Baroreceptor Reflex

Anatomy Simplified – Q&A – Series 1

Question 1: On your first day during your rotation, a medical attending ask you about external carotid artery and its branches. You recall that all of these are the branches of external carotid, EXCEPT:

1. Occipital artery
2. Facial artery
3. Superior thyroid artery
4. Inferior thyroid artery
5. Maxillary artery
6. Ascending pharyngeal artery

Answer:

4. Inferior thyroid artery.

Branches of external carotid arteries are:

Superior thyroid artery
Ascending pharyngeal artery
Lingual artery
Facial artery
Occipital artery
Posterior auricular artery
Maxillary artery
Superficial temporal artery

Here is the mnemonic to remember these branches by: Some Angry Lady Figured Out PMS


Question 2: A case of road traffic accident is brought to the emergency department. History showed that it was a motorcyclist who sustained injury on his head and was unconscious when he arrived in emergency room. However, he regains consciousness within few hours and therefore is subsequently discharged. As soon as he leaves the premises, he becomes unconscious once again. Which artery do you think is involved in this injury?

1. Anterior cerebral artery
2. Middle cerebral artery
3. Posterior cerebral artery
4. Middle meningeal artery
5. Posterior communicating artery

Answer: It would be - 4. Middle meningeal artery. This is because it is most likely to rupture during traumatic head injuries, especially towards the temple. Once ruptured, extradural hemorrhage develops and starts to compress the brain substance; thus, proving life threatening. A CT scan would be diagnostic.

Hypertexts Versus Text books

An excellent resourceful website that makes a very good substitution for textbooks. This great find helps you master Endocrine and Digestive Systems' Pathophysiology. In addition, it also focuses on Biotechnology and Medical Genetics.

Link: Hypertext for Biomedical Sciences