07/25/2017

Physiology mci screening test and indian medical pg examz high yield important topics study tips

By Live Dr - Wed Feb 11, 3:22 am

Physiology

Normal blood volume
5-5.5 liters (3 litre plasma + 2 litre of cell volume)

Intracellular fluid -55%

Extracellular fluid -45%

Normal protein level
Total plasma protein in blood is 6.4-8.3 gm/dl

Normal albumin: globulin ratio is 1.8: 1 -2:1

Normal values for
Na+ 135-145 meq/l
K+ 3.5-5.5  meq/l
Ca++ 9-11 meq/l
Normal ABG values
Ph 7.35-7.45
PCO2 35-45 mm of Hg
Po2 85-100 mm of Hg
HCO3 25-28 meq/l
O2 saturation 92-96 %

*Normal anion gap-8-16 meq/l

Skeletal muscle fibres

type 1 type2
Slow Fast
Oxidative Glycolytic
Red White
Non-fatiguable Fatiguable

FUNCTION OF CELL ORGANELLES

Mitochondria Production of energy
Rough endoplasmic reticulum Packaging of proteins
Smooth endoplasmic reticulum Lipid synthesis
Ribosomes Protein synthesis
Golgi apparatus Concentration of proteins and polysaccharides
Centriole Initiate the process of cell division
Lysosome Break down bacteria and debris from dead tissue cells
Peroxisomes Destroy harmful substances

TRIVIAL TRUTH

The average human body contains enough iron to make a 3 inch nail, sulfur to kill all fleas on an average dog, carbon to make 900 pencils, potassium to fire a toy cannon, fat to make 7 bars of soap, phosphorous to make 2,200 match heads!

ELEVENTH HOUR  PHYSIOLOGY                                                                                                            20

TYPES OF CELL TRANSPORT

Passive diffusion

(simple passive + facilitated diffusions)

Transport of a substance along the gradient , energy is not required
Simple passive diffusion Diffusion along the gradient, without the requirement of carrier.

Not rate limiting

Doesn’t follow saturation kinetics

Facilitated diffusion Diffusion of a substance which is mediated by carrier, Without requirement of energy

Rate limiting

Follows saturation kinetics

Primary active transport Transport against gradient

Energy is obtained  by breakdown of atp

Requires transport protein

Rate limiting and saturable.

Secondary active transport Energy for transport is derived from sodium gradient Transport against gradient

Requires transport protein

Rate limiting and saturable.

Rheobase The least strength of current which excites the excitable tissue
Chronaxie Minimum time required to stimulate the excitable tissue when strength of the current used is double the rheobasic.1

RECEPTORS WITH THEIR FUNCTIONS

Free nerve endings Detect touch and pressure
Meissner’s corpuscles Detect movement of light touch
Merkel’s disc Localizing touch sensations and determining texture
Hair end organs Detect the movement of objects on the surface of body
Ruffini’s end organs Detect degree of joint movement
Paccinian corpuscles Detect tissue vibration extremely rapid changes in mechanical state of tissue.

*Muller’s doctrine of specific nerve energies.

When the nerve pathways from particular sense organs are stimulated, the sensation evoked is that for which the receptor is specialized no matter how or where along the pathway the activity os initiated.

QUOTE CORNER

A person is only as big as the dream they dare to live.- Anonymous

ELEVETN HOUR PHYSIOLOGY                                                                                                                21

*Brain detects intensity of stimulus by

Variation in the frequency of action potentials generated by the stimulus  and

By variation in the number of receptors activated by the stimulus

*Weber Fechner law

Interpreted signal strength = Log x stimulus intensity + constant

O2 dissociation curve

Shift to right Shift to left
Decreased Ph

Increased temperature

Increased 2,3 dpg

Increased Ph

Decreased temperature

Fetal hemoglobin

*Bohr effect- effect of CO2 in the affinity of Hb for O2

Shift of oxygen hemoglobin dissociation curve by change in the blood CO2, and hydrogen ions to enhance oxygenation of blood in lungs and to enhance release of oxygen from blood in the tissues.

*Haldane effect-

Binding of oxygen with hemoglobin tends to displace CO2 from blood.

Important in promoting carbon dioxide transport.

hb a α2β2
hb a2 α2δ2
hb f α2γ2
Bart’s hb γ4
Hb Gower ζ2ε2

*Landsteiner’s law-

States that if an agglutinogen is present in the red cells of the blood, the corresponding agglutinin must be absent from the plasma, if the agglutinogen is absent, corresponding agglutinin must be present in the plasma.

Major cross matching Matching of donors cells with recipients plasma
Minor cross matching Matching of recipients cells with donors plasma
Normal glomerular filtration rate-125 ml.
Renal blood flow-1200ml/min
Renal threshold for glucose- 180 mg/dl

Renal threshold for glucose is 350mg/min

Tubular maximum for glucose is 320 mg/ min.

TRIVIAL TRUTH

The average human produces 25,000 quarts of spit in a lifetime, enough to fill two swimming pools.

ELEVENTH HOUR PHYSIOLOGY                                                                                                             22

Zona glomerulosa Aldosterone
Zona fasciculata Cortisol
Zona reticularis Androgens

Juxtaglomerular apparatus

Macula densa Epithelial cells of the initial part of distal tubule, lying in the angle between afferent and efferent arteriole of the glomerulus.
Juxtaglomerular cells/ granular cells Smooth muscle cells of afferent and efferent arterioles , containing dark granules, coming in contact with macula densa
Macroglia cns macrophages
Astrocytes Maintain blood brain barrier,

Repair and scar formation

Oligodendrocytes Formation of myelin
Ependymal cells Line the ventricular system

ROUTE OF CSF FLOW

Choroid plexus

Lateral ventricle

Foramen of Monro

Third ventricle

Aqueduct of Sylvius

Fourth ventricle

Foramina of Luschka

and Magendie

Subarachnoid space

Arachnoid villi

Venous outflow

Hypothalamus

Lateral nucleus Feeding centre
Ventromedial nucleus Satiety centre

QUOTE CORNER

Ability is what you’re capable of doing. Motivation determines what you do. Attitude determines how well you do it. – Lou Holtz

ELEVENTH HOUR PHYSIOLOGY                                                                                                             23

Kluver Bucy syndrome
Due to ablation of amygdala

Not afraid of anything

Has extreme curiosity about everything

Forgets rapidly

Has tendency to place everything I  its mouth, tries to eat solid objects

Strong sex drive

*Sham Rage behaviour

Physical and motor manifestation of anger seen in destruction of ventromedial hypothalamic nuclei and septal nuclei.

ROOT VALUE OF REFLEXES

Ankle jerk S1 S2
Knee jerk L3,4
Biceps reflex C5,6
Triceps jerk C7,8
Radial jerk C6
Jaw jerk Pons
Plantar reflex S12
Abdominal reflex T7-T11
Cremasteric reflex L1
Shy-Drager syndrome
Multiple system atrophy

Sympathetic and parasympathetic failure

Plasma norepinephrine/ dopamine ratio is more than 1

*Cushing’s reflex-

The reflex that tends to restore the blood flow to medulla by causing rise in systemic arterial pressure, slowing of respiration and reflex bradycardia in case of raised intracranial pressure

*Bainbridge reflex-

A true reflex rather than local response to stretch, causes receptor mediated increase in heart rate, is abolished by bilateral Vagotomy

Gaba is the most common inhibitory neurotransmitter used by the central nervous system

TRIVIAL TRUTH

Most people have lost fifty per cent of their taste buds by the time they reach the age of sixty.

ELEVENTH HOUR PHYSIOLOGY                                                                                                             24

*Starling’s law-

Within physiological limits, force of contraction is directly proportional to the initial length of the muscle fibres, provided conditions remain the same.

*Bezold Jarisch reflex-

Is a coronary chemoreflex mediated by left ventricular stretch  receptors that are  C fibres endings, it causes a fall in systemic arterial pressure and heart rate and apnoea followed by rapid breathing.

Postural hypotension
Fall in blood systolic pressures

Of more than 20 mm of hg

After standing for 3 min from lying posture

Or

10 mm reduction in diastolic pressure within 3 min of standing from lying posture

Stroke volume Volume of blood that is ejected by each ventricle with each beat

It is normally 70 ml.

Ventricular end diastolic volume Volume of blood in the ventricle just prior to the onset of ventricular contraction.

Normal-110-120 ml.

Ventricular end systolic volume Volume of blood remaining in the ventricle at the end of ejection

Normally-40-50 ml.

eeg characteristic normal duration event recorded
p wave 0.08 Atrial depolarization
pr interval 0.12 -0.20 sec Atrial depolarization and conduction through av node measured from beginning of QRS complex.
qrs duration 0.08-0.10 sec Ventricular depolarization and atrial repolarisation
st interval 0.32 sec Ventricular repolarisation
t wave Ventricular repolarisation
u wave Slow repolarisation of papillary muscles

*Most common cause of sudden death in young athletes is hypertrophic cardiomyopathy

QUOTE CORNER

Perfection is giving your all, so those who think those who try their hardest and fail aren’t reaching perfection, they’re wrong, because if you try your hardest, you have reached perfection”. – Adam Murphy

ELEVENTH HOUR PHYSIOLOGY                                                                                                             25

GASTROINTESTINAL HORMONES

hormone actions location stimulating factors inhibitory factors
Gastrin Increases acid and pepsin production, Promotes gastric emptying G cells of stomach and duodenum Stomach distention,

Vagal stimulation,

Protein digestion products,

Hypercalcemia

Low stomach Ph.
Secretin Stimulates the secretion of bicarbonate and water from liver, pancreas and Brunner’s glands

Inhibits G cells,

Enhances cholecystokinin.

Increases intestinal motility.

S cells of duodenum in the crypts of Lieberkuhn Low Ph of duodenum High Ph of duodenum
Cholecystokinin-

Pancreatozymin.

Increases pancreatic secretion,

contraction of gall bladder, Increases outflow of bile,

Inhibits gastric emptying, Enhances action of secretin, Increases intestinal motility.

Mucosa of small intestine Fat in chyme

Gastric inhibitory peptide Inhibits gastric secretion, motility.

Stimulates insulin secretion

K cells in the mucosa of duodenum

TRIVIAL TRUTH

Right handed people, on average, live nine years longer than left handed people!

ELEVENTH HOUR PHYSIOLOGY                                                                                                             26

GASTROINTESTINAL HORMONES CONTINUED…

hormone actions location stimulating factors inhibitory factors
Vasoactive intestinal peptide Stimulates intestinal secretion of electrolytes and water

Inhibits gastric secretion.

Relaxes intestinal smooth muscles and sphincters.

Nerves in GIT

INSULIN RECEPTORS

SGLT 1 Small intestine glucose absorption

(secondary active transport)

SGLT 2 Glucose absorption in renal tubules
GLUT 2 Beta cells of islet of Langerhans
GLUT 4 Insulin stimulates glucose uptake in muscles and adipose
GLUT 1 & 3 Basal glucose uptake by various tissues

Gastric acid secretion

Excitatory Inhibitory
Neural Acetylcholine Enterogastric reflex
Hormonal Gastrin Enterogastrone
Paracrine Histamine Somatostatin

*Choleretics-substances which increase the secretion of bile acid

Bile salts are the most potent choleretics

*Ito cells are fat containing lipocytes in the space of Disse of the liver

Metabolise and store vitamin A

Secrete collagen

Kupffer cells are phagocytic cells, part of monocyte and macrophage cells

RESPIRATORY CAPACITIES AND VOLUMES

Tidal volume Air that is taken in or given out during normal quiet respiration
Inspiratory reserve volume Air that can be taken in over and above the tidal volume
Expiratory reserve volume Maximum volume of air that can be expired over and above the tidal volume

QUOTE CORNER

It is a long hard road to overnight success. – Anonymous

ELEVENTH HOUR PHYSIOLOGY                                                                                                             27

RESPIRATORY CAPACITIES AND VOLUMES CONTINUED…

Residual volume Volume of air that remains in the lungs after forceful expiration

It can be determined by body Plethysmography or by Helium dilution methods

Inspiratory capacity

ic=irv + tv

Maximum volume of air that can be inspired after normal tidal expiration
Functional residual capacity Frc= erv + rv Volume of air remaining in the lungs after normal tidal expiration
vital capacity

Vc= irv +tv+ erv

Maximum volume of air that can be expired after deepest possible inspiration
Total lung capacity Sum of vital capacity and residual volume

*Herring Breurer reflex-

The stretch receptors in bronchi and bronchioles send inhibitory signals through vagi to inspiratory centre when the lung is overinflated.

*Cushing’s response

Onset of irregular respiration, bradycardia and final increased blood pressure with increasing intracranial tension due to brain stem compression

Hormone receptors

cell membrane receptors

cAMP pathway Adrenaline, Calcitonin, Glucagons, TSH, FSH, LH, ACTH, PTH.
IP3-DAG Vasopressin, Oxytocin
Tyrosine-kinase Insulin, Growth hormone.
Cytoplasmic receptors Steroids i.e. Glucocorticoids, Mineralocorticoids, Estrogen, Progesterone.
Nuclear receptors Thyroxin.
Proteins Half-life
Albumin 2-3 weeks
Transferrin 1 week
Pre-albumin, retinol binding protein. 2 days
Fibronectin 1 day.

TRIVIAL TRUTH

The psychedelic effects of LSD were serendipitously discovered by Albert Hofmann. A chemist, he accidentally ingested a small amount of it upon investigating its properties, and had the first acid trip in history, while cycling to his home in Switzerland.

ELEVENTH HOUR PHYSIOLOGY                                                                                                             28

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