A + P

Question 1

What is the Munroe Kelly doctrine?

Answer 1

The sum of volumes of brain, cerebrospinal fluid (CSF) and intracerebral blood is constant. An increase in one should cause a reciprocal decrease in either one or both of the remaining two.

Question 2

What are the partial pressures of oxygen and carbon dioxide at the following sites of the body: Alveoli / pulmonary capillaries, Pulmonary veins, arteries, systemic capillaries, veins, pulmonary artery?

Answer 2

Alveoli / Pulmonary capillaries: PO2 105 CO2 40
Pulmonary veins: PO2 100 CO2 40
Arteries: PO2 100 CO2 40
Systemic capillaries: PO2 40 CO2 50
Veins: PO2 40 CO2 45
Pulmonary artery: PO” 40 CO2 45

Question 3

Cholinergic effects

Answer 3

Pinpoint pupils, salivation, diaphoresis, GI distress, emesis

Question 4

Anti cholinergic effects

Answer 4

Dilated pupils, increased HR, absent bowel sounds, dry mucous membranes

Question 5

Blood vessels affected inferior STEMI

Answer 5

90% RCA. 10% LCx

Question 6

Blood vessels affected anterior STEMI

Answer 6

LAD

Question 7

Blood vessels affected lateral STEMI

Answer 7

Left circumflex

Question 8

Blood vessels affected posterior STEMI

Answer 8

RCA (right dominated heart) LCx or LAD (left dominated heart – less common)

Question 9

Blood vessels affected septal STEMI

Answer 9

Proximal LAD

Question 10

What is Frank-Starling Mechanism?

Answer 10

Represents the relationship between stroke volume and end diastolic volume. The law states that the stroke volume of the heart increases in response to an increase in the volume of blood in the ventricles, before contraction (the end diastolic volume), when all other factors remain constant.[

Question 11

How does heart failure affect the Frank Starling Graph

Answer 11

Right shifted (ie, a higher filling pressure is required to achieve the same cardiac output)

Question 12

Describe Primary TBI vs Secondary TBI

Answer 12

In traumatic brain injury (TBI), primary brain injury occurs during the initial insult, and results from displacement of the physical structures of the brain. Secondary brain injury occurs gradually and may involve an array of cellular processes.

Question 13

Whats the most common culprit vessel in TBI

Answer 13

The middle meningeal artery. The middle meningeal artery is a branch of the maxillary artery, which is itself a branch of the external carotid artery. It supplies the dura mater, the outermost layer of the meninges, which covers and protects the brain.

Question 14

Common causes Secondary TBI

Answer 14

Ischemia, hypoxia, hypo/hypertension, cerebral edema, raised intracranial pressure, hypercapnia, meningitis and brain abscess, biochemical changes ,
epilepsy.

Question 15

Vessels involved, location, symptom profile and etiology of Epidural Hematoma

Answer 15

Vessels Involved: Middle meningeal artery (commonly).
Location: Bleeding occurs between the inner surface of the skull and the dura mater.
Symptom Profile: Initial loss of consciousness followed by a lucid interval, then a rapid decline in mental status. Other symptoms may include headache, nausea, vomiting, focal neurological deficits.
Etiology: Typically caused by a skull fracture or a direct blow to the head, resulting in damage to the middle meningeal artery.

Question 16

Vessels involved, location, symptom profile and etiology of Subdural Hematoma

Answer 16

Vessels Involved: Bridging veins (most common) or cortical arteries.
Location: Bleeding occurs between the dura mater and the arachnoid mater.
Symptom Profile: Symptoms may develop immediately or have a delayed onset. Common symptoms include headache, confusion, drowsiness, focal neurological deficits, seizures.
Etiology: Often caused by head trauma, particularly when there is acceleration-deceleration or rotational forces leading to stretching or tearing of the bridging veins.

Question 17

Vessels involved, location, symptom profile and etiology of Intracerebral Hemorrhage:

Answer 17

Vessels Involved: Small arteries or arterioles within the brain.
Location: Bleeding occurs within the brain tissue itself.
Symptom Profile: Symptoms vary depending on the location and size of the hemorrhage but may include sudden-onset severe headache, loss of consciousness, nausea, vomiting, focal neurological deficits, changes in vision, speech, or motor function.
Etiology: Common causes include hypertension (high blood pressure), cerebral amyloid angiopathy, arteriovenous malformations, trauma, and certain medical conditions or medications that affect blood clotting.

Question 18

Vessels involved, location, symptom profile and etiology of Subarachnoid Hemorrhage

Answer 18

Vessels Involved: Typically caused by rupture of an intracranial aneurysm (abnormal bulging of a blood vessel) within the subarachnoid space.
Location: Bleeding occurs within the subarachnoid space, which is between the arachnoid mater and the pia mater.
Symptom Profile: Sudden and severe headache (often described as “thunderclap” headache), neck stiffness, photophobia, nausea, vomiting, altered mental status, focal neurological deficits.
Etiology: Most commonly caused by the rupture of a cerebral aneurysm, but can also result from trauma, arteriovenous malformations, or other vascular abnormalities.

Question 19

Layers from skull to brain

Answer 19

Scalp and Skull: The outermost layers of the head consist of the scalp and skull.
Dura Mater: The dura mater is the outermost layer of the meninges, which are the protective membranes surrounding the brain and spinal cord. The dura mater is a tough, fibrous membrane that adheres to the inner surface of the skull and helps provide support and protection to the brain.
Arachnoid Mater: The arachnoid mater is the middle layer of the meninges. It is a thin, delicate membrane located between the dura mater and the innermost layer, the pia mater. The arachnoid mater helps cushion and protect the brain and contains cerebrospinal fluid (CSF), which circulates around the brain and spinal cord.
Subarachnoid Space: The subarachnoid space is a fluid-filled space between the arachnoid mater and the pia mater. It contains the CSF that surrounds and bathes the brain and spinal cord, providing further protection and cushioning.
Pia Mater: The pia mater is the innermost layer of the meninges and is in direct contact with the surface of the brain. It is a thin, delicate membrane that adheres closely to the contours of the brain, covering its gyri (folds) and sulci (grooves).
Brain Parenchyma: The brain parenchyma refers to the actual brain tissue composed of gray matter and white matter. Gray matter consists of neuron cell bodies, while white matter consists of bundles of nerve fibers (axons) surrounded by myelin sheaths.

Question 20

How to calculate ICP, MAP and CCP

Answer 20

ICP: The measurement of ICP is typically obtained through invasive methods using specialized monitoring devices, such as intraventricular catheters or intraparenchymal monitors.
MAP: MAP = (Systolic Blood Pressure + 2 * Diastolic Blood Pressure) / 3
CCP: MAP - ICP

Question 21

What is the oxygen disassociation curve

Answer 21

The oxygen dissociation curve is a graphical representation of the relationship between the partial pressure of oxygen (PO2) and the saturation of hemoglobin (SaO2) with oxygen in the blood. It demonstrates how hemoglobin affinity for oxygen changes with varying oxygen tensions. The shape of the oxygen dissociation curve is sigmoidal (S-shaped) .

Question 22

What causes rightward shift oxygen disassociation curve

Answer 22

A rightward shift of the oxygen dissociation curve indicates a decreased affinity of hemoglobin for oxygen, meaning that oxygen is more readily released to the tissues. Several factors can cause a rightward shift:
Increased Temperature:
Increased Carbon Dioxide (CO2) Level
Increased Hydrogen Ion Concentration (Decreased pH)
Increased 2,3-Diphosphoglycerate (2,3-DPG):

Question 23

What causes leftward shift oxygen disassociation curve

Answer 23

A leftward shift of the oxygen dissociation curve indicates an increased affinity of hemoglobin for oxygen, resulting in enhanced oxygen binding. Few factors can cause a leftward shift:
Decreased Temperature
Decreased Carbon Dioxide (CO2) Levels
Increased pH
Reduce H+
Decreased 2,3 DPG

Question 24

What occurs in the cardiac action potential cycle

Answer 24

Phase 0 - Depolarization:
Ion Movement: Rapid influx of sodium ions (Na+).

Phase 1 - Early Repolarization:
Ion Movement: Transient outward current, Efflux of potassium ions (K+).

Phase 2 - Plateau Phase:
Ion Movement: Influx of calcium ions (Ca2+), Partial efflux of potassium ions (K+).

Phase 3 - Repolarization:
Ion Movement: Efflux of potassium ions (K+).

Phase 4 - Resting Potential:
Ion Movement: Steady-state ion movement.
Key Points: In phase 4, the cell membrane is at the resting membrane potential, typically around -90 mV. During this phase, the balance between ion movements, primarily involving potassium ions (K+), is maintained to keep the cell at its resting state, ready for the next action potential.

Question 25

Phrenic nerve location and function

Answer 25

It originates from the cervical spinal nerves C3, C4, and C5, and provides motor innervation to the diaphragm,

Question 26

12 cranial nerves

Answer 26

Olfactory Nerve (I):
Function: Sense of smell.

Optic Nerve (II):
Function: Vision.

Oculomotor Nerve (III):
Function: Eye movement (raising eyelids,

Trochlear Nerve (IV):
Function: Eye movement (superior oblique muscle).

Trigeminal Nerve (V):
Function: Sensation of the face, chewing.

Abducens Nerve (VI):
Function: Eye movement (lateral rectus muscle).

Facial Nerve (VII):
Function: Facial expression, taste, salivation, tears.

Vestibulocochlear Nerve (VIII):
Function: Hearing and balance.

Glossopharyngeal Nerve (IX):
Function: Taste, swallowing, salivation, monitoring carotid body and sinus.

Vagus Nerve (X):
Function: Sensation and movement of organs in the thoracic and abdominal cavities. Controls many autonomic functions, such as heart rate, digestion, and respiratory reflexes.

Accessory Nerve (XI):
Function: Neck and shoulder movements.

Hypoglossal Nerve (XII):
Function: Tongue movement.

Question 27

Function and trigger for activation Renin-angiotensin system

Answer 27

The renin-angiotensin system (RAS) is a hormonal system that plays a critical role in regulating blood pressure, fluid balance, and electrolyte homeostasis in the body.
The RAS is primarily activated in response to low blood pressure, decreased blood volume, or low sodium levels in the body.

Question 28

How is carbon dioxide transported in blood?

Answer 28

Carbon dioxide (CO2) is transported in the blood through three main mechanisms:
Dissolved CO2: A small portion of CO2 dissolves directly in the blood plasma. This dissolved CO2 accounts for about 5-10% of the total CO2 transported.
Carbaminohemoglobin: CO2 binds reversibly to hemoglobin, forming carbaminohemoglobin. This occurs mainly in the deoxygenated blood, where hemoglobin has a higher affinity for CO2. Carbaminohemoglobin accounts for approximately 20-30% of CO2 transport.
Bicarbonate (HCO3-) Formation: The majority of CO2 (around 60-70%) is converted to bicarbonate ions (HCO3-) within red blood cells.

Question 29

Bicarbonate buffer system equation

Answer 29

CO2 + H2O ⇌ H2CO3 ⇌ H+ + HCO3-
Carbon dioxide + water ⇌ Carbonic acid ⇌ Hydrogen and Bicarbonate

Question 30

Daltons gas law

Answer 30

Dalton’s law states that the total pressure exerted by a mixture of gases is equal to the sum of the partial pressures of each gas in the mixture.
This law is important in understanding gas exchange in the respiratory system. For example, the partial pressure of oxygen (PO2) in the alveoli contributes to the overall pressure of oxygen in the lungs.

Question 31

Henry’s Law

Answer 31

Henry’s law states that the amount of gas dissolved in a liquid is directly proportional to the partial pressure of the gas above the liquid.
This law is relevant to gas exchange in the bloodstream. It explains how gases, such as oxygen and carbon dioxide, dissolve in the blood plasma and can be transported to and from the tissues.

Question 32

The Haldane Effect

Answer 32

The Haldane effect describes the phenomenon where the oxygenation of hemoglobin in the blood affects its ability to carry carbon dioxide.
When hemoglobin binds to oxygen (oxyhemoglobin), it has a reduced capacity to bind carbon dioxide. Conversely, when hemoglobin is deoxygenated, it has an increased capacity to bind carbon dioxide.
This effect contributes to the efficient transport of carbon dioxide from the tissues to the lungs for elimination.

Question 33

The Bohr Effect

Answer 33

The Bohr effect explains the relationship between pH and the oxygen affinity of hemoglobin.
When there is an increase in acidity (decrease in pH), such as in metabolically active tissues, the affinity of hemoglobin for oxygen decreases. This promotes the release of oxygen from hemoglobin, allowing it to be delivered to the tissues.
The Bohr effect helps ensure that oxygen is released from hemoglobin in areas of high metabolic demand.

Question 34

Anaphylaxis Patho

Answer 34

Immune system has generated IgE antibodies to allergen.
During later exposure to the same allergen, the allergen binds to the IgE antibodies present on the surface of mast cells and basophils.
The binding of the allergen to the IgE antibodies triggers the activation of mast cells and basophils, leading to degranulation. Degranulation involves the release of various inflammatory mediators , including histamine, leukotrienes, prostaglandins, and cytokines.
The released inflammatory mediators cause a rapid and widespread systemic inflammatory response. Some of the key effects include:
Vasodilation, Increased Vascular Permeability,
Smooth Muscle Contraction / bronchoconstriction:, The systemic inflammatory response can affect multiple organ systems, leading to a wide range of symptomsincluding:: difficulty breathing, wheezing, swelling of the face or throat, hives or skin rash, gastrointestinal disturbances (vomiting, diarrhea), dizziness, and a rapid or weak pulse.

Question 35

Asthma Pathophys

Answer 35

Chronic Airway Inflammation driven by immune cells
Hyperresponsiveness of Airways leading to excessive bronchoconstriction and airway narrowing.
Bronchoconstriction
Airway Remodeling including thickening of the airway walls, increased mucus production, and hypertrophy of the airway smooth muscles.
Increased Mucus Production: The chronic inflammation in asthma triggers an increased production of mucus by goblet cells in the airway epithelium.
IgE-Mediated Immune Response: In individuals with allergic asthma, the immune system produces specific antibodies called immunoglobulin E (IgE) in response to allergens.
Inflammatory Mediators: Inflammatory mediators released during asthma attacks include histamine, leukotrienes, prostaglandins, and cytokines. These mediators cause increased vascular permeability, smooth muscle contraction, mucus production, and recruitment of additional inflammatory cells.
Triggers and Exacerbating Factors: Asthma symptoms can be triggered or exacerbated by various factors, such as allergens (pollen, dust mites), irritants (smoke, strong odors), respiratory infections, exercise, cold air, and stress.

Question 36

Common causes metabolic acidosis

Answer 36

Diabetic Ketoacidosis (DKA), Renal Failure,
Lactic Acidosis, Salicylate Poisoning, Severe Diarrhea

Question 37

Common causes metabolic alkalosis

Answer 37

Vomiting or Nasogastric Suctioning, Excessive Use of Antacids, Excessive Diuretic Use, Hypokalemia

Question 38

Common causes respiratory acidosis

Answer 38

Chronic Obstructive Pulmonary Disease (COPD), Respiratory Depression,
Chest Wall Abnormalities (eg obestity or chest trauma)

Question 39

Common causes respiratory alkalosis

Answer 39

Hyperventilation, Hypoxemia, Mechanical Ventilation

Question 40

Physiological changes in pregnancy

Answer 40

Hormonal Changes:
Increased estrogen and progesterone
Human chorionic gonadotropin (hCG) is produced
Cardiovascular Changes:
Increased blood volume by up to 50%
Increased cardiac output, heart rate, and stroke volume.
Expansion of blood vessels
Physiological anemia
Respiratory Changes:
Increased oxygen demand
Elevated respiratory rate
Slight increase in tidal volume.
Renal Changes:
Increased kidney blood flow and glomerular filtration rate (GFR).
Increased urine production
Decreased bladder capacity
Gastrointestinal Changes:
Increased appetite and food intake
Relaxation of gastrointestinal smooth muscles, leading to decreased gastric motility and potential for acid reflux and heartburn.

Question 41

Pregnancy Trimesters

Answer 41

1st trimester: Week 1-12
2nd trimester: Week 13 - 27
3rd Trimester: Week 28-40+

Question 42

Stages of labour

Answer 42

Stage 1: Early Labor, Active Labor, and Transition:
Early Labor: This stage marks the beginning of contractions and the gradual dilation and effacement of the cervix. Contractions may be irregular and mild at first, gradually becoming stronger and more regular.
Active Labor: During this phase, the contractions become stronger, longer, and closer together, usually about 3-5 minutes apart. The cervix continues to dilate more rapidly, reaching around 6-7 centimeters.
Transition: The transition phase is the most intense and challenging part of labor. Contractions are strong, frequent, and last longer. The cervix fully dilates to 10 centimeters during this stage.
Stage 2: Pushing and Delivery:
Once the cervix is fully dilated, the second stage begins. The delivery of the baby marks the end of stage 2.
Stage 3: Delivery of the Placenta:

Question 43

Differences in Paediatric airway

Answer 43

Size and Proportions: The pediatric airway is smaller and more narrow than an adult airway. The airway structures, including the larynx, trachea, and bronchi, are relatively smaller in diameter and length in children.
Position of the Larynx: In infants and young children, the larynx is positioned higher in the neck compared to adults.
Epiglottis: The epiglottis in pediatric patients tends to be larger, softer, and more omega-shaped compared to the narrower, more erect epiglottis in adults.
Narrowest Points: The narrowest points of the pediatric airway are located at the cricoid cartilage and subglottic area, rather than at the vocal cords as in adults. This makes children more susceptible to airway obstruction in these areas, especially during inflammation or swelling.
Relatively Larger Tongue: Children have relatively larger tongues compared to their oral cavity size, which can potentially contribute to airway obstruction, especially in the unconscious or sedated child.
Increased Collapsibility: The pediatric airway is more collapsible and prone to obstruction due to its smaller size, less developed cartilage, and surrounding soft tissues. This increased collapsibility can make children more vulnerable to airway obstruction during respiratory distress or upper respiratory infections.
Faster Respiratory Rate: Children typically have a faster respiratory rate than adults. Their higher respiratory rate, combined with the smaller airway diameter, increases the resistance to airflow, making them more susceptible to respiratory distress.

Question 44

What are the three blood vessels that come off the aorta?

Answer 44

Brachiocephalic Trunk (Innominate Artery)
Left Common Carotid Artery
Left Subclavian Artery

Question 45

Most commonly distrupted blood vessels pelvic fracture?

Answer 45

Internal Iliac Artery: The internal iliac arteries are major blood vessels located within the pelvis. They supply blood to various structures in the pelvic region, including the pelvic organs, gluteal muscles, and pelvic walls.
External Iliac Artery: The external iliac artery is another important blood vessel that runs along the front of the pelvis. It becomes the common femoral artery as it passes under the inguinal ligament and supplies blood to the lower limbs.
Obturator Artery: The obturator artery is a smaller blood vessel that arises from the internal iliac artery. It courses through the obturator canal, supplying blood to the inner thigh muscles and nearby structures.
Sacral Arteries: The sacral arteries provide blood supply to the sacrum, the triangular bone at the base of the spine.

Question 46

Compare absolute and relative refractory period

Answer 46

The absolute refractory period is the period during which a cell is completely unresponsive to any new stimulus, regardless of its strength.
It occurs immediately after the cell depolarizes and generates an action potential.
The relative refractory period follows the absolute refractory period.
During this period, the cell has repolarized to some extent but is still in a hyperpolarized state.
While the cell is in a hyperpolarized state, it requires a stronger-than-normal stimulus to generate an action potential.
The relative refractory period occurs because some of the ion channels responsible for generating action potentials have recovered and can be activated, albeit with a higher threshold.
If a strong enough stimulus is applied during the relative refractory period, it can trigger a new action potential.

Question 47

Croup Pathophysiology

Answer 47

Croup is characterized by inflammation and swelling of the upper airways, particularly the larynx and trachea.

Question 48

How does adrenaline relieve airway obstruction in the croup patient

Answer 48

When administered as a nebulized mist, adrenaline acts locally on the airways, providing rapid relief of the inflammation and swelling associated with croup. : Adrenaline causes vasoconstriction, which means it constricts the blood vessels in the affected area. In the context of croup, adrenaline reduces the swelling and inflammation of the upper airways, including the larynx and trachea. This vasoconstrictive effect helps to decrease the engorgement of blood vessels in the swollen airway tissues, allowing the airways to open up more effectively.
Bronchodilation: Adrenaline has bronchodilatory properties, meaning it relaxes the smooth muscles in the airway walls. This bronchodilatory effect helps to counteract the narrowing of the upper airways that occurs in croup, particularly during inspiration.
Reduction of Mucus Secretion: Adrenaline can also reduce mucus production in the airways.

Question 49

Why give adrenaline cardiac arrest

Answer 49

Vasoconstriction to increase BP and improve coronary and cerebral perfusion pressure

Question 50

Why give adrenaline cardiac arrest

Answer 50

Vasoconstriction to increase BP and improve coronary and cerebral perfusion pressure