October, 2010 | Master Of Medicine

Monthly Archives: October 2010

EEG waves

EEG has four types of waves alpha,beta,theta and delta.

Consider a  family where mother has passed away leaving 3 children in the protection of father.The father will be the head of family(consider him as alpha), next comes the son who is a college student(Beta), the third child is younger 6 years(theta), the youngest child is an infant(delta).

Alpha wave

  1. Most prominent wave of EEG with frequency of 10-12Hz.
  2. Most marked in the parieto occipital area
  3. Seen in humans who are awake but at rest with mind wandering and eyes closed.
  4. Seen in stage 0 and 1 of NREM sleep.

Beta wave

  1. Asynchronous waves of higher frequency of 18-30 Hz but lower amplitude.
  2. Most marked in frontal area.
  3. Seen in human when awake persons attention is directed to some specific mental activity
  4. Not seen in any stage of sleep,replace alpha waves when an awake person at rest opens his eyes.

Theta waves

  1. Frequency of 4-7 Hz and large amplitude
  2. Most marked in parietal and temporal region in children
  3. They occur normally in children and in stage II and III of NREM sleep.

Delta wave

  1. Slow waves with a frequency <4Hz and a very large amplitude.
  2. Seen in infancy and serious organic brain damage.
  3. Seen in stage III and IV of NREM sleep(deep sleep).

Important Points

  1. Sleep spindles and K complexes occur in stage II of NREM sleep.
  2. Sleep spindles are short spindle shaped bursts of alpha waves that occur periodically in NREM sleep.
  3. Frequency decreases and amplitude increases as we proceed from alpha to delta, the only exception is beta(highest frequency).

Relation with sleep

Stage 0 -alpha- close eyes beta-open eyes
stage 1 -alpha +theta
stage 2- theta waves spindles k complexes
stage 3- delta theta and spindle
stage 4-delta
REM sleep-all frequency of waves

Alpha waves (8-11 Hz) are slower and larger. They are associated with a state of relaxation and basically represent thebrain shifting into idling gear, relaxed and disengaged, waiting to respond when needed. If one merely closes his or her eyes and begins picturing something peaceful, in less than half a minute there will be an increase in alpha brainwaves. Alpha is present typically when one feels at ease and calm or in a position to change one’s mind efficiently and effectively in order to accomplish a task.
Sensory Motor Rhythm (12-15 Hz) measured over the sensorimotor cortex are brain waves associated with mental alertness and readiness for action, combined with behavioural stillness.
Beta waves (16 Hz and above) are small, faster brainwaves associated with a state of mental or intellectual activity and outwardly focused concentration. Beta waves are present when one is thinking, problem solving, processing information, or anxious.

Delta brain waves (1-3 Hz) are the slowest, highest amplitude brainwaves, and are present primarily during sleep or when in an empathetic state. Excess delta activity in the awake state is usually indicative of dysfunction.
Theta waves (4-8 Hz) are present when daydreaming or fantasising. At the same time, creativity and intuition are also associated with theta waves. This contrast occurs because theta waves occur at two levels: The lower range of theta (4-5 Hz) basically represents the twilight zone between waking and sleep. It is a profoundly calm, serene, floaty, drifty state. In this range, conscious intellectual activity is not occurring. It is also the range of frequencies produced in excess by children and adults with ADHD.

Anterior and posterior cruciate ligaments

ACL and PCL are almost exactly opposite in their functions.

Anterior cruciate Ligament

  1. Major stabilizer of knee
  2. Limits anterior translation of tibia on femur
  3. Limits hyper extension of knee
  4. Attached on tibia just behind anterior horn of medial meniscus
  5. Runs upwards forwards,backwards and laterally.
  6. Attached on femur over medial surface of lateral femoral condyle
  7. Intracapsular and intrasynovial
  8. Taut during extension of knee
  9. Injury is by a twisting force on a semiflexed knee

Posterior cruciate Ligament

  1. Prevents posterior tanslation of tibia on femur
  2. Limits hyperextension of knee only if ACL is ruptured
  3. Attached to  tibia behind posterior horn of medial meniscus
  4. Runs upwards forwards and medially
  5. Attached on femur over lateral surface of medial femoral condyle
  6. Intracapsular but extrasynovial
  7. Taut during flexion of knee
  8. Dashboard impact injury is the most common type of injury

Membranes and Ligaments of Larynx

Ligaments and membranes of Larynx are divided into extrinsic and intrinsic

Membranes of Larynx

Extrinsic-Thyrohyoid membrane

Intrinsic-Quadrangular membrane,Cricothyroid membrane,conus elasticus

Ligaments of larynx

Extrinsic

  1. Median thyrohyoid ligament
  2. Lateral thyrohyoid ligament
  3. Hyoepiglottic ligament
  4. Cricotracheal ligament

Intrinsic

  1. Anterior/median cricothyroid ligament
  2. Thyroepiglottic ligament.

Tip: Everything with Hyoid in it is extrinsic, also add cricotracheal ligament the extrinsic list is complete.

Glucose transporters

Glucose enters cells by facilitated diffusion or by secondary active transport with Sodium(in intestine and kidneys)

Glucose transporters(Glut 1-7) are responsible for facilitated diffusion of glucose across cell membranes.

They differ from sodium dependant glucose transporters(SGLT1 and 2)

Glucose Transporters and their functions

GLUT-1

Basal glucose uptake

Present in brain,kidney,colon,placenta and erythrocytes.

GLUT 2

Beta cell glucose sensor

Transport glucose out of intestinal and renal epithelial cells

Beta cells of pancreas,liver,Small Intestine,Kidneys.

GLUT 3

Basal glucose uptake

Brain,placenta,Kidney

GLUT4

Insulin stimulated glucose uptake

Present in skeletal and cardiac muscle,adipose tissue.

GLUT 5

Fructose transport

Jejunum and sperm

Glut 6

Pseudogene

GLUT 7

Glucose 6 phosphate transporter in endoplasmic reticulum.

Liver

Na+ Glucose co-transporters

SGLT 1

Absorption of glucose from Small Intestine and renal tubules

SGLT 2

Absorption of glucose from renal tubules.

Important points

  1. Basal glucose uptake by- GLUT1 and GLUT3
  2. GLUT 2 is present in beta cells of pancreas, so it controls postprandial hyperglycemia
  3. GLUT4 is insulin dependent so no of GLUT4 decreases after overnight fasting.

Anion Gap and acidosis

Anion Gap is of 2 types, plasma Anion gap and urinary anion gap

Plasma Anion Gap

Plasma Anion Gap refers to the amount of unmeasured anions present in the plasma.

Calculated by:[ Na+]     –     [Cl-]+[HCO3-]  or

[Na+] + [K+] – [Cl-]  + [HCO3-]

Normal Anion Gap- 10-12 meq

Delta Gap= Anion gap-12

Unmeasured anions-Proteins,phosphate,Sulfate,organic anions.

Points to be noted

  1. When the ion added is chloride, anion gap remains the same.
  2. Eg:Adding HCl leads to decrease in HCO3-(used for buffering H+) but the decrease in HCO3- is balanced by an increase in Cl-.So it leads to normal anion gap metabolic acidosis,also called hyperchloremic metabolic acidosis.
  3. When the ion added is not chloride, anion gap widens.

Urine Anion Gap

[Na+]+[K+]-[Cl-]

In normal subjects urine anion gap is usually zero or positive.

Urine anion gap is negative if there is no distal acidification of urine.

In Renal Tubular acidosis Urine anion gap is normal.

High anion gap metabolic acidosis

A high anion gap indicates acidosis. e.g. In uncontrolled diabetes, there is an increase in ketoacids (i.e. an increase in unmeasured anions) and a resulting increase in the anion gap. In these conditions, bicarbonate concentrations decrease, in response to the need to buffer the increased presence of acids (as a result of the underlying condition). The bicarbonate is replaced by the unmeasured anion resulting in a high anion gap.

  • Methanol
  • Uremia
  • DKA/Alcoholic KA
  • Paraldehyde/propylene glycol(used in diazepam injns)
  • Isoniazid
  • Lactic Acidosis
  • Ethylene Glycol
  • Rhabdo/Renal Failure
  • Salicylates

Mnemonic:MUDPILERS

Normal Anion gap Metabolic acidosis

In patients with a normal anion gap the drop in HCO3 is compensated for almost completely by an increase in Cl and hence is also known as hyperchloremic acidosis.

The HCO3 lost is replaced by a chloride anion, and thus there is a normal anion gap.

  • Gastrointestinal loss of HCO3 (i.e., diarrhea) (vomiting causes hypochloraemic alkalosis)
  • Renal loss of HCO3 (i.e. proximal renal tubular acidosis(RTA) also known as type 2 RTA)
  • Renal dysfunction (i.e. distal renal tubular acidosis also known as type 1 RTA)
  • Ingestions
    • Ammonium chloride and Acetazolamide.
    • Hyperalimentation fluids (i.e. total parenteral nutrition)
  • Some cases of ketoacidosis, particularly during rehydration with Na+ containing IV solutions.
  • Mineralocorticoid deficiency (Addison’s disease)

FUSEDCARS (fistula (pancreatic), uretogastric conduits, saline administration, endocrine (hyperparathyroidism), diarrhea, carbonic anhydrase inhibitors (acetazolamide), ammonium chloride, renal tubular acidosis, spironolactone)

Summed up as:

Anion Gap Metabolic Acidosis: MUDPILERS

  • Methanol
  • Uremia
  • DKA/Alcoholic KA
  • Paraldehyde
  • Isoniazid
  • Lactic Acidosis
  • Ethylene Glycol
  • Rhabdo/Renal Failure
  • Salicylates

Non-Anion Gap Acidosis: HARDUPS

  • Hyperalimentation
  • Acetazolamide
  • Renal Tubular Acidosis
  • Diarrhea
  • Uretero-Pelvic Shunt
  • Post-Hypocapnia
  • Spironolactone

Acute Respiratory Acidosis  any hypoventilation state

  • CNS Depression (drugs/CVA)
  • Airway Obstruction
  • Pneumonia
  • Pulmonary Edema
  • Hemo/Pneumothorax
  • Myopathy
Chronic Respiratory Acidosis = COPD/restrictive lung dz

Metabolic Alkalosis: CLEVER PD

  • Contraction
  • Licorice
  • Endocrine:Conns
  • Cushing’s/Bartter’s
  • Vomiting
  • Excess Alkali
  • Refeeding Alkalosis

Respiratory Alkalosis: CHAMPS (think speed up breathing)

  • CNS disease
  • Hypoxia
  • Anxiety
  • Mech Ventilators
  • Progesterone
  • Salicylates/Sepsis

Low anion gap

A low anion gap is frequently caused by hypoalbuminemia. Albumin is a negatively charged protein and its loss from the serum results in the retention of other negatively charged ions such as chloride and bicarbonate. As bicarbonate and chloride anions are used to calculate the anion gap, there is a subsequent decrease in the gap.

In hypoalbuminaemia the anion gap is reduced from between 2.5 to 3 mmol/L per g/dL decrease in serum albumin.Common conditions that reduce serum albumin in the clinical setting are hemorrhage, nephrotic syndrome, intestinal obstruction and liver cirrhosis.

The anion gap is sometimes reduced in multiple myeloma, where there is an increase in plasma IgG (paraproteinaemia).

Saturated and Unsaturated Oils

  1. Coconut Oil
  2. Butter
  3. Palmoil(MUFA-44)
  4. Cottonseed oil
  5. Margarine
  6. Groundnut Oil
  7. Soyabean Oil
  8. Sunflower seed Oil
  9. Safflower Oil
  10. Corn Oil

Saturated fats

Very bad for health.Content of saturated fats decreases from top to bottom in the list.

So Cocunut Oil(92%),butter and Palmoil have the maximum saturated fats and are least healthy.

whereas Soyabean Oil,Sunflower Oil,Safflower Oil and corn oil have least saturated fattyacids

MUFA and PUFA

Both are good for health.

Maximum MUFA in Groundnut Oil(50%)

PUFA

  1. Soyabean Oil(62)
  2. Sunflower Oil(65)
  3. Safflower(65)
  4. CornOil(60)

Drugs removed by forced alkaline diuresis

Forced alkaline diuresis is done with bicarbonate,urea,furesamide,mannitol

Weak acids are removed by Forced alkaline diuresis and weak alkali removed by forced acid diuresis

Alkaline diuresis

  1. Salicylates
  2. Long acting barbiturates
  3. Chlorpropamide
  4. Methotrexate

Acid Diuresis

  1. Amphetamines
  2. Quinine

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