Physiology High Yield Terms
1. Obesity is a medical condition in which excess body fats has accumulated to the extent that it may have an adverse
effect on health, leading to reduced life expectancy and/or increased health problems. Body mass index (BMI), a
measurement which compares weight and height, defines people as over weight (pre-obese) if their BMI is
between 25 and 30 kg/m2, and obese when it is greater than 30 kg/m An abnormal increase in the proportion of fat
cells, mainly in the viscera and subcutaneous tissues of the body.
2. Hypoxia is the deficiency of oxygen at the tissue level. It occurs in the entire body. Hypoxia usually results from low
oxygen content in the inspired air, insufficient pulmonary ventilation, defective gas exchange. Deficient uptake and
utilization of oxygen by cells, very low atmospheric pressure etc.
3.
Nephritis is the inflammation of the nephrones in the kidneys. The word "nephritis" was imported from Latin. The
word comes from the Greek - nephro- meaning "of the kidney" and -itis meaning "inflammation". Nephritis is the
most common producer of glomerular injury. It is a disturbance of the glomerular structure with inflammatory cell
proliferation. This can lead to reduced glomerular blood flow, leading to reduced urine output and retention of
waste products. As a result, red blood cells may leak out of damaged glomeruli, causing blood to appear in the
urine haematuria. Nephritis is a serious medical condition which is the eighth highest cause of human death. As the
kidneys inflame, they begin to excrete needed protein from the body into the urine stream. This condition is called
proteinuria. Loss of necessary protein due to nephritis can result in several life-threatening symptoms.
4.
Thrombosis is the formation of a blood clot or thrombus within the blood vessels. It blocks blood vessels and
obstructs the flow of blood. This may cause serious cardiovascular problems. Thrombosis depends upon the same
factors that are involved in the coagulation of blood on the surface of the body. The following are the serious three
thrombosis like coronary, cerebral and pulmonary thrombosis.
5. ECG. The monitoring and record of the potential fluctuations during cardiac cycle is the eletrocardioram (ECG).
Usually the electrocardiograph machine records these fluctuations on a moving strip of paper. It gives correct
information regarding the rhythm and rate of heart beat and thus helps to detect disorders of heart.
6. Cori cycle. The cycle of reactions by which muscle lactic acid is transformed to muscle glycogen is known as Cori
cycle or lactate glucose cycle.
7. Action potential. Changes in the permeability of the nerve membrane to potassium and sodium ions lead to
changes in the potential differences across the membrane. This ,in turn results in the formation and propagation of
nerve impulse. When a resting neuron gets stimulated a cyclic series of electro-chemical changes takes place in it.
This is known as action potential.
8. Dialysis. It is the process of separating colloids and crystalline substances in solution by the different in their rate of
diffusion through a semipermeable membrane. It is a medical procedure for te removal of certain elements from
the blood or lymph by the virtue of the difference in their rates diffusion through an external semipermeable
membrane. Dialysis may be used to remove poisons and excessive amounts of wastes etc in patient with chronic
renal diseases. There are two types of dialysis, namely haemo dialysis and peritoneal dialysis.
9. Nitrogen excretion. Excretion is the separation and elimination of metabolic wastes and the excess of essential
materials from the body to maintain homeostasis. The nitrogenous wastes are highly varied. The commonest one
among them are ammonia, urea and uric acid. Based on the chemical nature of the excretory products,four major
kinds of excretion can be recognized. They are ammonotelism, uricotelism, ureotelism and guanotelism.
Ammonotelic animals are entirely aquatic, uricotelic and guanotelic animals are exclusively terrestrial and ureotelic
animals include both aquatic and terrestrial forms.
10. Myogenic and Neurogenic hearts. Based on the stimulation for heart, two kinds of hears can be recognized,
myogenic and neurogenic. In myogenic hearts, the cardiac muscle fibres have the autonomous ability to
spontaneously initiate and maintain heart beats without nervous stimulation. So the rhythmicity of the heart beat is
determined by the cardiac muscles themselves. In neurogenic hearts, heart-beats are initiated and maintained by
nervous stimulation and neural control. The hearts of mollusks and vertebrates are myogenic and those
crustaceans, spiders, insects etc. are neurogenic
11. Carbon monoxide poisoning. Carbonmonoxide poisoning is the excessive concentration of CO in blood. It is a major
occupational hazard among the workers in mines. CO is a product of the incomplete combustion of fuels. The
affinity of Hb for CO is nearly 300 times greater than that for oxygen. So, Hb combines more readily and rapidly
with CO than with O2 and forms a stable product called carboxyhaemoglobin. The CO poisoning considerably
reduces the delivery of oxygen to tissues and eventually leads to severe anoxia.
12. Types of hearts. Structural and anatomical basis the hearts are classified into four types like 1. Pulsating hearts 2.
Tubular hearts 3. Ampullar or Accessory hears and 4. Chambered hearts. On the basis of the nature of blood in the
heart, three types of hearts are recognized. 1. Single circuit hearts 2. Transitional hearts and 3. Double hearts.
Physiologist have recognized two types of hearts depending upon the control of cardiac rhythm namely 1. The
myogenic and 2. Neurogenic hearts.
13. Biochemical changes during muscle contraction. Muscular contraction is the shortening of myofibrils, in response
to a nervous stimulations. Muscular contraction involves two sets of events, namely physical and biochemical
events. The physical changes during muscular contraction include the regular and cyclic attachment and
detachment between the myosin cross bridges and the actin filaments.
14. Transport of carbon dioxide. Blood transport CO2 from tissues to lungs in three ways as 1. As carbonic acid 2. As
carbaminohaemoglobin and 3. As bicarbonates. In the first case CO2 reacts with plasma water and forms the weak
carbonic acid. On reaching the lungs, carbonic acid dissociates and relases CO2. In man abour 5% of CO2 is
transported in this manner. In the second type of transport, the CO2 first diffuses from plasma to RBC and then
reversibly combines with the amino group of the globin part and forms carbaminohaemoglobin. On reaching the
pulmonary capillaries, the carbaminohaemoglobin dissociates and releasing CO2. In man, about 85% of CO2 is
transported in chemical combination as bicarbonates.
15. Nerve impulse transmission. A message carried along a neuron is called a nerve impulse. The neurons function by
propagating nerve impulse. In a resting neuron the cell membrane bears an electrical charge. Normally the external
surface of the membrane is positively charged and the inner surface is negatively charged. Mention the resting
membrane potential, depolarization, repolarization, action potential and the details of nerve impulse transmission
in myelinated and nonmyelinated nerves.
16. Asphyxia.Asphyxia is a state of breathing arrest in which the normal intake, distribution and utilization of oxygen
get seriously impaired. Asphyxia can be general or local. Prolonged asphyxia may ultimately result in brain damage,
unconsciousness, or death. The effects of asphyxia are gradual.
17. Respiratory pigments. Respiratory pigments are complex, colored and metal containing conjugated proteins
involved in the uptake, storage and transport of respiratory gases. They have very great affinity for oxygen. They
consists of protein coupled with a non-protein component (prosthetic group). The prosthetic group is a metal,
usually iron or copper. The commonest respiratory pigments include haemoglobin, myoglobin, haemocyanin,
haemerythrin and chlorocruorin
18. EEG. EEG is the imaging technique by which brain waves are recorded and measured for the diagnosis of brain
disorders. The instrument used for recording the electrical tracings of the cerebral cortex is called
electroencephalograph. EEG may contain four kinds of waves, namely alpha, beta, theta and delta.
19. All or none law. In order to elicit an impulse in a neuron the stimulus applied should be of a certain minimum
intensity or threshold. For eliciting an impulse a minimum intensity of stimulus is required, but once elicited the
impulse travels at a maximum speed irrespective of the intensity of the stimulus, this relationship is known as All or
None law.
20. Depolarization and Repolarization. When a neuron is stimulated the permeability properties of the membrane
change. In the region of stimulation there is a temporary suspension of the sodium pump and consequently there is
a rapid influx of sodium in that region. Thus there is momentary reversal of membrane charge, the internal surface
becoming electropositive and the external surface becoming electronegative. This momentary reversal of polarity
across the membrane is called depolarization. During depolarization the electric potential across the membrane
drops to zero. At this point the permeability characteristics of the membrane return to normal and the sodium
pump increases its activity. This recovery is called Repolarization.
21. Kidney transplantation. Artificial kidney is effective in helping victims of acute kidney malfunction to survive the
crisis. But this requires enormous time, money and psychological well being and an alternative to long term dialysis
for chronic kidney failure is the transplantation of a new kidney. In certain cases after operation there may develop
some problems of immune rejection. But by using immuno-suppressive drugs, many implanted kidneys remain
functional for several years.
22. Synapse and Synaptic transmission. Synapse is a functional junction between two neurons or between a neuron
and muscle cell. The former is called neuronal synapse and the latter, neuro-muscular synapse. The neuron, which
transmits impulse to a neuronal synapse, is called pre-synaptic neuron and the neuron which transmits impulses
away from the synapse is called post synaptic neuron. Transmission of impulses across synapses is called synaptic
transmission. Two mechanisms are believed to operate during synaptic transmission. They are electrical and
chemical transmission.
23. Diabetic mellitus and Diabetic insipidus. Diabetic mellitus is commonly called the sugar diabetes, is metabolic
disorder characterized by hyperglycemia and glycosuria, Its major symptoms are excessive urine production,
increased thrust, excessive hunger and weight loss. Diabetes insipidus is a disorder of water metabolism,
characterized by excessive excretion of dilute urine, increased thirst and heavy fluid intake and frequent urination. It
results from the inadequate renal reabsorption of water mainly due to the insensitivity of renal tubules to ADH.
24. Active transport. Active transport is the movement of a substance against its concentration gradient (from low to
high concentration). In all cells, this is usually concerned with accumulating high concentrations of molecules that
the cell needs, such as ions, glucose and amino acids.. Active transport uses energy, unlike passive transport which
does not use any type of energy. Active transport is a good example of a process for which cells require energy.
25. Reflex. Responses which are of an involuntary nature are known as the reflexes. The nervous elements that bring
about a reflex constitute the reflex arc. The reflex arc is considered to be the structural and functional basis of the
reflex. Reflexes are generally classified into two broad subdivisions, the simple and conditioned. A simple reflex is an
inborn, inherited or unlearned response to a stimulus. On the other hand, a conditioned reflex is a response
dependent on past experience. Knee jerk reflex is an example for simple reflex and Pavlov’s experiment on dog,
food with bell is an example for conditioned reflex.