Basic mnemonics in physiology - part one

Basic mnemonics in physiology - part one

Physiology is the study of normal functions of the body system. As it is said, if you don’t know the normal you can’t identify or know the abnormal. Therefore, there is a need to properly study this course before a medical student moves on to study pathology.


These mnemonics are written in order to facilitate easy remembrance of some terms which maybe forgotten so easily or confused. 


We will be discussing most of the mnemonics using three main subheadings which are:

  • Term/Item
  • Introduction
  • Mnemonic and its meaning

Happy reading


1. Heart: tropic: definitions

The heart is a muscular organ that pumps blood to whole body through a network of vessels i.e arteries and vein. Arteries carry blood away from heart and veins return the blood to the heart. This system is known as cardiovascular system.


Tropic or tropism of the heart is the innate ability possessed by the heart to turn or move in response to a stimulus.


The following are heart tropics and meaning:

  • Lusitropic: loose is relaxed. Definition: relaxation of the heart.
  • Inotropic: when heart wall contracts, moves inward. Definition: contraction of the heart.
  • Chronotropic: 'chrono-' means 'time'. Definition: heart rate (of SA node impulses).
  • Dromotropic: only one left, it must be conduction speed by default.


2. Heart valves: closure sequence

Human heart possesses four valves with which it regulates blood distribution in the body. The valves are mitral, tricuspid, aortic and pulmonary valves. It should be noted that the opening and closing of these valves are well coordinated and regulated. Disorder related to its coordinated movement, size of the valves can result in heart diseases like prolapse and so on.


So, the sequence of closure of the valves are:

  • "Many Things Are Possible":
  • Mitral, Tricuspid, Aortic, Pulmonic


3. Heart valves: sequence of flow

Check number 2 for brief explanation of heart valves.


Sequence of flow includes:


  • TRIcuspid
  • Pulmonary
  • Semilunar
  • BIcuspid
  • Aortic
  • Semilunar

  Alternatively: "TRIPS, MI ASs!" (uses MItral instead of BIcuspid)


4. Einthoven's Triangle: organization

Einthoven’s triangle is an imaginary equilateral triangle having the heart at its center and formed by lines that represent the three standard limb leads of the electrocardiogram.


Organization are:

  • Corners are at RA (right arm), LA (left arm), LL (left leg).
  • Number of L's at a corner tell how many + signs are at that corner [eg LL is ++].
  • Sum of number of L's of any 2 corners tells the name of the lead [eg LL-LA is lead III].
  • For reference axes, the negative angle hemisphere is on the half of the triangle drawing that has all the negative signs; positive angle hemisphere contains only positive signs.


5. Electrical conductivity of tissues

Electrical conductivity is a measure of how easily a material allows electric current to flow through it.


Electrical conductivity of tissue in order of least conductive to most conductive includes:

"Be Careful To Shock My Best Nerve":

  • Bones
  • Cartilage
  • Tendon
  • Skin
  • Muscle
  • Blood
  • Nerve


6. Heart electrical conduction pathway

This is a sequential order through which electric current flows in the heart. It begins at the sino-atrial node which is also known as pacemaker through arterio-venous node, to the bundle of His and finally to the punkinje fibers.


The pathway is:

"If patient's family are all having Heart attacks, you must SAVe HIS KIN!"

  • SA node --->
  • AV node --->
  • His (bundle of) -->
  • PurKINje fibers


7. Adrenal gland: functions

Adrenal glands are glands situated above the renal(kidney). It is divided into two compartment, the adrenal cortex which secretes the sex hormones (androgens, estrogens), hormones that regulate sodium balance in the blood (aldosterone), and sugar balance (cortisol) and the adrenal medulla which secretes catecholamines (fight or flight hormones).


Functions include:


  • Adrenergic functions
  • Catabolism of proteins/ Carbohydrate metabolism
  • T cell immunomodulation
  • Hyper/ Hypotension (blood pressure control)


8. Adrenal cortex: layers and products: 

Check the above for adrenal glands.


Adrenal cortex is basically divided into three layer and these layers are responsible for production of a typical hormones.


"Get your Facts Right, Men are Glued to their Gonads":

  • Glomerulosa
  • Fasciculata
  • Reticularis
  • Mineralocorticoids
  • Glucocorticoids
  • Gonadocorticoids [androgens]


So this means the product of glomerulosa is mineralocorticoid, that of fasciculata is glucocorticoid and finally that of reticularis is gonadocorticoid.




"Get All Fat Chicks Right Away":


  • Glomerulosa
  • Fasciculata
  • Reticularis



  • Aldosterone
  • Cortisol
  • Androgens


9. Diabetes Insipidus: diagnosing subtypes

Diabetes insipidus is a rare disorder characterized by passage of large volumes (>3 L/24 h) of dilute urine (< 300m Osm/kg). It is marked by intense thirst and urination.


Subtypes and how to diagnose are:


After a desmopression injection:

  • Concentrated urine = Cranial.
  • No effect = Nephrogenic.


10. Hyperthyroidism: signs and symptoms

Thyrotoxicosis is a condition in which there is an excessive amount of thyroid hormones in the blood resulting in hyper metabolic state. Thyroid function tests for hyperthyroidism and thyrotoxicosis are Thyroid-stimulating hormone (TSH), Free thyroxine (FT4), Total triiodothyronine (T3). The result of the test would show increase FT4 and T3 and suppression of TSH


Signs and symptoms include:


  • Tremor
  • Heart rate up
  • Yawning [fatigability]
  • Restlessness
  • Oligomenorrhea & amenorrhea
  • Intolerance to heat
  • Diarrhea
  • Irritability
  • Sweating
  • Muscle wasting & weight loss


11. LH vs FSH: function in male

Leutenizing hormone and follicle stimulating hormones are produced from anterior pituitary gland through the action of releasing hormone(GRH) produced in the hypothalamus. They are found in male and female, however their functions are different in the opposite sex.


Functions in male:

  • LH: Leydig cells stimulated to produce testosterone.
  • FSH: Spermatogenesis stimulated.


12. Oestrogen: functions

Oestrogen is a sex hormone produced by the ovary and responsible for the development and regulation of the female reproductive system and secondary sex characteristics. It should be noted that oestrogen can also be found in male.


Functions are:


  • Organ development (sex organs)
  • Endocrine: FSH and LH regulation
  • Secondary sex characteristics development
  • Tropic for pregnancy
  • Receptor synthesis (of progesterone, oestrogen, LH)
  • Osteoporosis decrease (inhibits bone reabsorption)
  • Granulosa cell development
  • Endocrine: increases prolactin secretion, but then blocks its effect
  • Nipple development
  • Sex drive increase
  • Uterine contractility increase
  • oXytocin sensitivity increase


13. Oxytocin-producing nucleus of hypothalamus

Oxytocin is one of the posterior pituitary gland hormones, the second being the anti- diuretic hormone. It should be however noted that these hormones are not produced in the pituitary glands, they are transported to it from the hypothalamus.


Producing nucleus of hypothalamus is:

  • Paraventricular nucleus--> Parturition (childbirth is oxytocin's most important role).


14. Prolactin and oxytocin: functions

Prolactin is produced in the anterior pituitary gland by the cells called lactotrophs. 


Check the above for oxytocin brief explanation.


Functions of oxytocin and prolactin are:

  • PROlactin stimulates the mammary glands to PROduce milk.
  • Oxytocin stimulates the mammary glands to Ooze (release) milk.


15. Pituitary hormones

Pituitary is an important organ in the body mainly because of its numerous functions especially in hormones production. It is divided into anterior and posterior pituitary hypophyses. Anterior pituitary hypophysis contains glands and different types of cells that help in production of hormones.


The posterior pituitary hormones does not produce hormones but stores and secretes: anti-diuretic hormone and oxytocin.


Hormones found in the pituitary glands are:


  • Follicle stimulating hormone
  • Lutinizing hormone
  • Adrenocorticotropin hormone
  • Growth hormone
  • Thyroid stimulating hormone
  • Oxytocin
  • Prolactin


Alternatively: GOAT FLAP with the second 'A' for Anti-diruetic homone/vasopressin


Note: there is also melanocyte secreting homone and Lipotropin, but they are not well understood.


16. Pituitary: anterior hypophysis hormones

Check number 15 for explanation.


Hormones found in the anterior pituitary hypophysis are:

FLAT P wave:

  • FSH
  • LH
  • ACTH
  • TSH
  • Prolactin


17. Progesterone: actions

Progesterone is an endogenous steroid hormone released by the corpus luteum in the ovary. It plays important roles in the menstrual cycle, pregnancy and embryogenesis. Exogenous Progesterone can be used as contraceptive alone or in combination with oestrogen.


Its actions are: 


  • Produce cervical mucous
  • Relax uterine smooth muscle
  • Oxytocin sensitivity down
  • Gonadotropin [FSH, LH] secretions down
  • Endometrial spiral arteries and secretions up
  • Sustain pregnancy
  • Temperature up / Tit development
  • Excitability of myometrium down


18. Alkalosis vs. acidosis: directions of pH and HCO3

Alkalosis is defined as the increase in pH of the body beyond the normal level which is 7.35-7.45. So anything above 7.45 is alkalosis, it can be caused by too much bicarbonate in the blood or a loss of acid(H+)  from the blood (metabolic alkalosis), or by a low level of carbon dioxide in the blood that results from hyperventilation (respiratory alkalosis). 


Acidosis is opposite of alkalosis, ie decreased in body pH below the normal level which is 7.35 – 7.45. It may be caused by reduction in bicarbonate (HCO3−), typically with compensatory reduction in carbon dioxide partial pressure (Pco2) in metabolic acidosis or  increase in carbon dioxide partial pressure (Pco2) with or without compensatory increase in bicarbonate (HCO3−) as seen in respiratory acidosis.


So, directions of pH are:


Respiratory= Opposite:

  • pH is high, PCO2 is down (Alkalosis).
  • pH is low, PCO2 is up (Acidosis).


Metabolic= Equal:

  • pH is high, HCO3 is high (Alkalosis).
  • pH is low, HCO3 is low (Acidosis).


19. Carotid sinus vs. carotid body: function

Carotid sinus is a dilated area at the base of the internal carotid artery just superior to the bifurcation of the internal and external carotid arteries at the level of the superior border of thyroid cartilage. It extends from the bifurcation to the "true" internal carotid artery. It senses pressure change.


Carotid body is a cluster of chemoreceptor cells, and supporting sustentacular cells. It is located in the adventitia of the common carotid artery, which runs along both sides of the neck.


Their functions are’

  • carotid SinuS: measures preSSure.
  • carotid bO2dy measures O2


20. Compliance of lungs: factors

Lungs compliance is defined as the measure of the extent to which lungs expand for each unit increase in the trans-pulmonary pressure. Lung Compliance (C) = Change in Lung Volume (V) / Change in Transpulmonary Pressure (Alveolar Pressure -  Pleural Pressure).


Some conditions can lead to increase or decrease in lungs compliance, these are:


  • Collagen deposition (fibrosis)
  • Ossification of costal cartilages
  • Major obesity
  • Pulmonary venous congestion
  • Lung size
  • Increased expanding pressure
  • Age
  • No surfactant
  • Chest wall scarring
  • Emphysema


NB: All but LEA decrease compliance.

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