স্পেশাল বিসিএস (স্বাস্থ্য) - লং কোর্স

Secretin is released from small intestine when stomach acid contents come to duodenum.
Functions:
• It inhibits gastric emptying to delay the acid contents of stomach to enter in the duodenum.
• It inhibits gastric secretion.
• It acts on pancreatic duct to produce large volume of watery, NaHCO₃ secretion.
• It stimulates the secretion of NaHCO₃ rich bile in the liver by acting on the bile ducts.

Following are the clinical indications for performing the Ghrelin Blood Test:
1. Gastric bypass surgery.
2. Monitoring obesity.
3. Rapid weight loss or weight gain.
4. Suspected anorexia nervosa

Factors That Cause a Hypoeffective Heart
► (1) Increased arterial pressure against which the heart must pump, such as in hypertension.
► (2) Inhibition of nervous excitation of the heart.
► (3) Pathological factors that cause abnormal heart rhythm or rate of heartbeat.
► (4) Coronary artery blockage, causing a "heart attack”.
► (5) Valvular heart disease.
► (6) Congenital heart disease.
► (7) Myocarditis, an inflammation of the heart muscle.

The sequential steps are as follows:

1.The bipolar cells of the spiral ganglion, which are located in the cochlea’s modiolus, are the first-order neurons of the auditory pathway.
2. The second-order auditory pathway neurons are made up of neurons from the dorsal and ventral cochlear nuclei in the medulla oblongata.
3. Both the superior olivary nuclei and the lateral lemniscus nucleus comprise the third-order neurons.
4.The subcortical auditory centre is formed by the medial geniculate body, where the fibres of third-order neurons terminate.
5.The nerve fibres from the medial geniculate body travel as auditory radiation via the internal capsule to the temporal cortex.
6.In the midbrain, the inferior colliculus of the tectum receives some fibres from the medial geniculate body.
7.The reflex movements in response to auditory stimuli are mediated by the auditory radiation fibres.
8.The temporal lobe of the cerebral cortex houses the cortical auditory centres. The perception of auditory impulses, analysis of sound pitch and intensity, and identification of sound source are all concerns of the cortical auditory centres.

Examples of Mechanoreceptors
Tactile receptors
1.Merkel cells- Specialised cells present in the epidermis, sense light touch and softness.
2. Meissner corpuscles- An encapsulated nerve ending, present at the upper part of the dermis. They can sense light touch and vibrations.
3. Ruffini endings- These are also encapsulated, present in the dermis. They sense heavy and continuous pressure.
4.Pacinian corpuscles- They are encapsulated by connective tissue, located deep in the dermis of the skin. They respond to deep pressure.

Propioreceptors
These receptors sense body movement and position and help in maintaining the posture. It is required for locomotion and motor skills.
1.Muscle spindles- sense muscular movement.
2.Golgi tendons- sense tension in the tendons during muscle contractions.
3.Joint receptors- sense movement in the ligaments.

Composition
FFP contains labile as well as stable components of the coagulation, fibrinolytic and complement systems, the protiens that maintain oncotic pressure and modulate immunity.
In addition fats, carbohydrates and minerals are present in concentrations similar to circulation.
The analysis of 35 samples of FFP show mean concentrations of of 535mg/dl Glucose, 172mEq/L. Na+, 73mEq/L Cl-, Cl-, 3.5mEq/Lk 3.5mEq/L. K+, 15mEq/L HCO3-and  protien with 60% albumin. 5-5g/dl
Thus FFP is a hyperosmolal, hyperglycemic, hypernatremic and hypochloremic solution.
It is a less effective volume expander than other albumin containing solutions, due to its lower albumin content.

Indications
Multiple coagulation factor deficiencies e.g.
DIC
Massive blood transfusion
Liver disease
Active or ongoing bleeding with abnormal coagulation tests
"Thrombotic thrombocytopaenic purpura
Vitamin K deficiency associated with active bleeding

• Heparin is a highly sulfated glycosaminoglycan with the highest negative charge density of any known biological molecule. It is a naturally occurring anticoagulant produced by mast cells and basophils that plays an important role in vivo in the fine balance of anticoagulant and procoagulant processes. Although it does not break down preformed clots like tissue plasminogen activator, it instead potentiates the progression of the body’s natural clot lysis mechanisms to prevent the formation of clots.

• Heparin is administered parenterally because it is not absorbed in the gut due to its high negative charge and size; intramuscular injections are avoided because of the risk of developing hematomas. Subcutaneous administration is predominantly given for deep vein thrombosis prophylaxis. In order to maintain its antithrombotic effect throughout the duration of percutaneous coronary intervention (PCI), heparin must be rebolused or continually infused because of its short half-life.

• Heparin is the most commonly used anticoagulant in the world administered to minimize thrombotic complications during PCI; its onset of action is immediate after intravenous administration. In addition to avoiding thrombotic complications, anticoagulation strategies must be designed to avoid major bleeding complications, as they are associated with increased morbidity, mortality, and cost.

• The combination of heparin and glycoprotein (GP) IIb/IIIa inhibitors has a potent anti-ischemic effect, but also has an increased risk of serious bleeding complications that must be balanced carefully. Although randomized trials have demonstrated the reduction of ischemic events with GP IIb/IIIa inhibitors in patients who undergo PCI for non-ST elevation acute coronary syndromes and ST-elevation myocardial infarction, bleeding complications are also increased.

The “no-reflow” phenomenon refers to the inability to reperfuse myocardial tissue despite the reopening of the infarct-related artery. No-reflow often happens in acute myocardial infarction patients during primary percutaneous coronary intervention (PCI), which has a strong negative impact on clinical outcome, negating the potential benefit of primary PCI. No-reflow is associated with a higher rate of mortality and early postinfarction complications.

QRS complexes with variable peaks that appear to twist around the isoelectric line characterize torsades de pointes (TDP).

• Predisposing risk factors for TDP include congenital channelopathies, severe bradycardia, drugs, and hypokalemia.

• Drug-induced TDP is of major concern because it can be life threatening; class IA/III antiarrhythmic agents, antipsychotics, antibiotics, and antihistamines are among the list of drugs that are noted to destabilize repolarization.

1. Cortical activation of the direct pathway leads to increased thalamic output
2. Cortical activation of the indirect pathway leads to decreased thalamic output
3.Substantia nigra activation (via D1) of the direct pathway leads to increased thalamic output
4. Substantia nigra inhibition (via D2) of the indirect pathway leads to increased thalamic output
It is the combination of these pathways that allows for precise control of motor movement, balancing the excitatory direct pathway with the inhibitory indirect pathway.

There are two types of bipolar cells:
a) OFF-center bipolar cells and
b) ON-center bipolar cells.
These cells respond in opposite ways to the glutamate released by the photoreceptors because they express different types of glutamate receptors. Like photoreceptors, the bipolar cells do not fire action potential and only respond with graded postsynaptic potentials

The H+/monocarboxylate cotransporter (MCT) recognizes monocarboxylates such as lactate, pyruvate, acetoacetate, and β-hydroxybutyrate. It is a proton-driven transporter with a coupling stoichiometry of 1 H+ : 1 monocarboxylate and, thus, MCT is an electroneutral transporter (Fig. 4). The direction of transport is governed by the prevailing proton gradient.

According to the NIH, the following desired values are used to measure an overall lipid profile:

LDL: Less than 160 mg/dL (if you have heart disease or diabetes, less than 100 mg/dL)
HDL: Greater than 40–60 mg/dL
Triglycerides: 10–150 mg/dL

Va/Q is infinity : No perfusion but ventilation remains normal.
Causes:
1. Embolism
2. Emphysema
3.Bronchiectasis

Volitional tests of respiratory include
a- Mouth Pressures (Maximal Static Inspiratory and Expirato Pressure).
b- Sniff Test
c- SNIP Test (Sniff pressure at nose measured )
d- Cough Tests

• It is produced during atrial systole and considered as physiologic heart sound.
Characteristics:
• It is short and low pitched sound.
• Duration of the sound is 0.02 -0.04 seconds.
Causes:
• It occurs due to vibrations which set up in atrial musculature during atrial systole.
Fourth heart sound and ECG:
• It coincides with interval between end of 'P' wave and onset of 'Q' wave in ECG.

Three Sources of Energy for Muscle Contraction

1)      The first source of energy that is used to reconstitute the ATP is the substance phosphocreatine, which carries a high-energy phosphate bond similar to the bonds of ATP.

2)      The second important source of energy, which is used to reconstitute both ATP and phosphocreatine, is a process called glycolysis-the breakdown of glycogen previously stored in the muscle cells.

3)      The third and final source of energy is oxidative metabolism, which means combining oxygen with the end products of glycolysis and with various other cellular foodstuffs to liberate ATP.

More than 95% of all energy used by the muscles for sustained long-term contraction is derived from oxidative metabolism.

Fast Fibers (Type II, White Muscle)
 The following are characteristics of fast fibers:
1. Fast fibers are large for great strength of contraction.
2. Fast fibers have an extensive sarcoplasmic reticulum for rapid release of calcium ions to initiate con- traction.
3. Large amounts of glycolytic enzymes are present in fast fibers for rapid release of energy by the glycolytic process.
4. Fast fibers have a less extensive blood supply than slow fibers because oxidative metabolism is of sec- ondary importance.
5. Fast fibers have fewer mitochondria than slow fibers, also because oxidative metabolism is secondary.
A deficit of red myoglobin in fast muscle gives it the name white muscle.

an analysis of the lever systems of the body depends on knowledge of the following:
(1) the point of muscle insertion;
(2) its distance from the fulcrum of the lever;
(3) the length of the lever arm;
and (4) the position of the lever.

The acetylcholine-gated channel has a diameter of about 0.65 nanometer, which is large enough to allow the important positive ions-sodium (Na+), potassium (K+), and calcium (Ca2+)-to move easily through the opening. Patch clamp studies have shown that one of these channels, when opened by acetylcholine, can transmit 15,000 to 30,000 sodium ions in 1 millisecond. Conversely, negative ions, such as chloride ions, do not pass through because of strong negative charges in the mouth of the channel that repel these negative ions.

1. The resting membrane potential is about -80 to -90 millivolts in skeletal fibers, about 10 to 20 millivolts more negative than in neurons.
2. The duration of the action potential is 1 to 5 milliseconds in skeletal muscle, about five times as long as in large myelinated nerves.
3. The velocity of conduction is 3 to 5 m/sec, about 1/13 the velocity of conduction in the large myelinated nerve fibers that excite skeletal muscle.

Treatment of malignant hyperthermia
a.rapid cooling
b. the administration of dantrolene, a drug that antagonizes ryanodine receptors, which inhibits calcium ion release for the sarcoplasmic reticulum and thereby attenuating muscle contraction.

Effect of Digitalis on the T Wave
 digitalis is a drug that can be used during heart failure to increase the strength of cardiac muscle contraction. However, when an overdose of digitalis is given, depolarization duration in one part of the ventricles may be increased out of proportion to that of other parts. As a result, nonspecific changes, such as T-wave inversion or biphasic T waves, may occur in one or more of the electrocardiographic leads.

Therefore, changes in the T wave during digitalis administration are often the earliest signs of digitalis toxicity.

• Intrapleural space: -8 mm Hg
• Joint synovial spaces: -4 to -6 mm Hg
• Epidural space: -4 to -6 mm Hg

Sweet-tasting compounds are detected by a combination of two closely related G-protein-coupled taste receptors, T1R2 and T1R3.
The receptors responsible for umami taste is believed to be a complex of T1R1 and T1R3 proteins. Thus, T1R3 appears to function as a co- receptor for sweet and umami tastes.
Bitter taste is sensed by another family (T2R) of approximately 30 different G-protein coupled receptors. Individual bitter-sensing taste receptor cells express multiple T2Rs, each of which recognizes a unique set of bitter compounds.
Sour taste, associated with acidic food or drink, is believed to be sensed by ion channels that are opened by hydrogen ions although the precise mechanisms are not fully understood. Recent studies suggest that an acid- sensitive potassium channel (KIR2.1) and a hydrogen ion-selective ion channel (otopetrin 1) may mediate acid responses in taste receptor cells

Brain Areas for Control of the Gamma Motor System
The gamma efferent system is excited specifically by signals from the bulboreticular facilitatory region of the brain stem
and, secondarily, by impulses transmitted into the bulboreticular area from the following: (1) the cerebellum; (2) the basal ganglia; and (3) the cerebral cortex.
Because the bulboreticular facilitatory area is particularly concerned with antigravity contractions, and because the antigravity muscles have an especially high density of muscle spindles, the gamma efferent mechanism is believed to be important for damping the movements of the different body parts during walking and running.

Function of brainstem
1. Control of respiration
2. Control of the cardiovascular system
3. Partial control of gastrointestinal function
4. Control of many stereotyped movements of the body
5. Control of equilibrium
6. Control of eye movements

When RBCs are delivered from the bone marrow into the circulatory system, they normally circulate an average of 120 days before being destroyed. Even though mature RBCs do not have a nucleus, mitochondria, or endoplasmic reticulum, they do have cytoplasmic enzymes that are capa- ble of metabolizing glucose and forming small amounts of adenosine triphosphate.
These enzymes also do the following:
(1) maintain pliability of the cell membrane;
(2) maintain membrane transport of ions;
(3) keep the iron of the cells' hemoglobin in the ferrous form rather than the ferric form;
(4) prevent oxidation of the proteins in the RBCs.
Even so, the metabolic systems of old RBCs become progressively less active, and the cells become more and more fragile, presumably because their life processes wear out.

Secondary Polycythemia
Whenever the tissues become hypoxic because of too little oxygen in the breathed air, such as at high altitudes, or because of failure of oxy- gen delivery to the tissues, such as in cardiac failure, the blood-forming organs automatically produce large quantities of extra RBCs. This condition is called secondary polycythemia, and the RBC count commonly rises to 6 to 7 million/mm³, about 30% above normal.

A common type of secondary polycythemia, called phys iological polycythemia, occurs in those who live at altitudes of 14,000 to 17,000 feet, where the atmospheric oxygen is very low. The blood count is generally 6 to 7 million/mm³, which allows these people to perform reasonably high lev- els of continuous work, even in a rarefied atmosphere.

Effects of Leukemia on the Body
The first effect of leukemia is metastatic growth of leukemic cells in abnormal areas of the body. Leukemic cells from the bone marrow may reproduce so much that they invade the surrounding bone, causing pain and, eventually, a tendency for bones to fracture easily.
Almost all leukemias eventually spread to the spleen, lymph nodes, liver, and other vascular regions, regardless of whether the leukemia originated in the bone marrow or lymph nodes.
Common effects in leukemia are the development of infection, severe anemia, and a bleeding tendency caused by thrombocytopenia (lack of platelets). These effects result mainly from displacement of the normal bone marrow and lymphoid cells by the nonfunctional leukemic cells.

Finally, an important effect of leukemia on the body is excessive use of metabolic substrates by the growing cancerous cells. The leukemic tissues reproduce new cells so rapidly that tremendous demands are made on the body reserves for foodstuffs, specific amino acids, and vitamins. Consequently, the energy of the patient is greatly depleted, and excessive utilization of amino acids by leukemic cells causes especially rapid deterioration of the normal protein tissues of the body. Thus, while the leukemic tissues grow, other tissues become debilitated. After metabolic starvation has continued long enough, this factor alone is sufficient to cause death.
Bibliography
David BA, Kubes P: Exploring the complex role of chemokines and chemoattractants in vivo on leukocyte dynamics Immunol Re

When the antibody is highly specific, there are so many bonding sites that the antibody-antigen coupling is exceedingly strong,
held together by (1) hydrophobic bonding; (2) hydrogen bonding; (3) ionic attractions; and (4) Van der Waals forces.
It also obeys the thermodynamic mass action law

Acute Kidney Failure After Transfusion Reactions

One of the most lethal effects of transfusion reactions is kidney failure, which can begin within a few minutes to a few hours and continue until the person dies of acute renal failure.

The kidney shutdown seems to have three causes:

1. The antigen-antibody reaction of the transfusion reaction releases toxic substances from the hemolyzing blood that cause powerful renal vasoconstriction

2. Loss of circulating RBCs in the recipient, along with production of toxic substances from the hemolyzed cells and the immune reaction, often. cause circulatory shock. The arterial blood pressure falls very low, and renal blood flow and urine output decrease.

3. If the total amount of free hemoglobin released into the circulating blood is greater than the quantity that can bind with haptoglobin (a plasma protein that binds small amounts of hemoglobin), much of the excess leaks through the glomerular membranes into the kidney tubules.

Energy Required for Respiration.
During normal quiet respiration, only 3% to 5% of the total energy expended by the body is required for pulmonary ventilation. However, during heavy exercise, the amount of energy required can increase as much as 50-fold, especially if the person has any degree of increased airway resistance or decreased pulmo- nary compliance. Therefore, one of the major limitations on the intensity of exercise that can be performed is the person's ability to provide enough muscle energy for the respiratory process alone.

During strenuous exercise, O2 consumption and CO2 formation can increase as much as 20-fold.
Yet, in the healthy athlete, alveolar ventilation ordinarily increases almost exactly in step with the increased level of oxygen metabolism.
The arterial PO2, PCO2, and pH remain almost exactly normal. In trying to analyze what causes the increased ven-

The three major organs of articulation are the lips,tongue,  and soft palate. 

The resonators include the mouth, the nose and associated nasal sinuses, the pharynx, and even the chest cavity. 

Zones 1, 2, and 3 of Pulmonary Blood Flow
The capillaries in the alveolar walls are distended by the blood pressure inside them but simultaneously are compressed by the alveolar air pressure on their outsides. Therefore, whenever the lung alveolar air pressure becomes greater than the capillary blood pressure, the capillaries close, and there is no blood flow.
Under different normal and pathological lung conditions, one may find any one of three possible zones (patterns) of pulmonary blood flow, as follows:

Zone 1: No blood flow during all portions of the cardiac cycle because the local alveolar capillary pressure in that area of the lung never rises higher than the alveolar air pressure during any part of the cardiac cycle
Zone 2: Intermittent blood flow only during the peaks of pulmonary arterial pressure because the systolic pressure is then greater than the alveolar air pressure, but the diastolic pressure is less than the alveolar air pressure
Zone 3: Continuous blood flow because the alveolar capillary pressure are remains greater than alveolar air pressure during the entire cardiac cycle

Normally, the lungs have only zones 2 and 3 blood flow-zone 2 (intermittent flow) in the apices and zone 3 (continuous flow) in all the lower areas.

Vasopressin:
Cys-Tyr-Phe-Gln-Asn-Cys-Pro-Arg- GlyNH2
Oxytocin:
Cys-Tyr-Ile-Gln-Asn-Cys-Pro-Leu-GlyNH2 

TSH, also known as thyrotropin, is an anterior pituitary hormone; it is a glycoprotein with a molecular weight of about 28,000. This hormone increases secretion of thyroxine and triiodothyronine by the thyroid gland. It has the following specific effects on the thyroid gland:
1. Increased proteolysis of thyroglobulin that has already been stored in the follicles, releasing the thyroid hormones into the circulating blood and diminishing the follicular substance
2. Increased activity of the iodide pump, which increases the rate of "iodide trapping" in the glandular cells, sometimes increasing the ratio of intracellular to extracellular iodide concentration in the glandu- lar substance to as much as eight times normal
3. Increased iodination of tyrosine to form the thyroid hormones
4. Increased size and increased secretory activity of the thyroid cells
5. Increased number of thyroid cells plus a change from cuboidal to columnar cells and much infolding of the thyroid epithelium into the follicles
In summary, TSH increases all the known secretory activities of the thyroid glandular cells.

The most important early effect after administration of TSH is to initiate proteolysis of thyroglobulin, which causes release of thyroxine and triiodothyronine into the blood within 30 minutes. The other effects require hours or even days and weeks to develop fully.

The fluid in the lumen of the seminiferous tubules is quite different from plasma; it contains very little protein and glucose but is rich in androgens, estrogens, K+, inositol, and glutamic and aspartic acids.
Maintenance of its composition depends on the blood-testis barrier. The barrier also protects the germ cells from bloodborne noxious agents, prevents antigenic products of germ cell division and maturation from entering the circulation and generating an autoimmune response, and may help establish an osmotic gradient that facilitates movement of fluid into the tubular lumen.

Semen
The fluid that is ejaculated at the time of orgasm, the semen, contains sperm and the secretions of the seminal vesicles, prostate, Cowper glands, and, probably, the urethral glands. An average volume per ejaculate is 2.5-3.5 mL after several days of abstinence from sexual activity. The volume of semen and the sperm count decrease rapidly with repeated ejaculation.
Even though it takes only one sperm to fertilize the ovum, each milliliter of semen normally contains about 100 million sperm. Reduction in sperm production is associated with infertility: 50% of men with counts of 20-40 million/mL and essentially all of those with counts under 20 million/mL are sterile. The presence of many morphologically abnormal or immotile spermatozoa also correlates with infertility.
The prostaglandins in semen, which come from the seminal vesicles, are at high concentrations, but their function in semen is unknown. The causes of male infertility, as well as the underlying mechanisms of sperm in fertilization, are used as clues in developing male contraception .

Testosterone, the principal hormone of the testes, is a C19 steroid with a hydroxyl group in the 17 position . It is synthesized from cholesterol in the Leydig cells and is also formed from androstenedione secreted by the adrenal cortex. 

Based on differences in the resting tone in muscles and the limbs involved, CP is classified into different groups.
The most prevalent type is spastic CP that is characterized by spasticity, hyperreflexia, clonus, and a positive Babinski sign.
These are all signs of damage to the corticospinal tract .
Dyskinetic CP is characterized by abnormal involuntary movements (chorea and athetosis) and may reflect damage to extrapyramidal motor areas. It is not uncommon to have signs of both types of CP.
The rarest type is hypotonic CP that presents with truncal and extremity hypotonia, hyperreflexia, and persistent primitive reflexes.

PREMOTOR CORTEX
The premotor cortex is located anterior to the precentral gyrus, on the lateral and medial cortical surface; it contains a somatotopic map.
This region receives input from sensory regions of the parietal cortex and projects to M1, the spinal cord, and the brainstem reticular formation.
This region is concerned with setting posture at the start of a planned movement and with getting the individual prepared to move.
It is most involved in control of proximal limb muscles needed to orient the body for movement.

Uncal Herniation
Space-occupying lesions from large tumors, hemorrhages, strokes, or abscesses in the cerebral hemisphere can drive the uncus of the temporal lobe over the edge of the cerebellar tentorium, compressing the ipsilateral cranial nerve III (uncal herniation).
Before the herniation these patients experience a decreased level of consciousness, lethargy, poorly reactive pupils, deviation of the eye to a "down and out" position, hyperactive reflexes, and a bilateral Babinski sign (due to compression of the ipsilateral corticospinal tract).
After the brain herniates, the patients are decerebrate and comatose, have fixed and dilated pupils, and eye movements are absent. Once damage extends to the midbrain, a Cheyne-Stokes respiratory pattern develops.

The other cortical cell types are local circuit interneurons and are classified based on their shape, pattern of projection, and neurotransmitter. Inhibitory interneurons (basket cells and chandelier cells) release GABA as their neurotransmitter. Basket cells have long axonal endings that surround the soma of pyramidal neurons; they account for most inhibitory synapses on the pyramidal soma and dendrites. Chandelier cells are a powerful source of inhibition of pyramidal neurons because their axonal endings terminate

exclusively on the initial segment of the pyramidal cell axon. Their terminal boutons form short vertical rows that resemble candlesticks, thus accounting for their name. Spiny stellate cells are excitatory neurons that release glutamate; these multipolar interneurons are located primarily in layer IV and are a major recipient of sensory information arising from the thalamus.

In addition to being organized into layers, the cerebral cortex is also organized into columns. Neurons within a column have similar response properties, suggesting they comprise a local processing network (eg, orientation and ocular dominance columns in the visual cortex).

ASCENDING AROUSAL SYSTEM
The ascending arousal system is a complex polysynaptic pathway comprised of monoaminergic, cholinergic, and histaminergic neurons that project to the intralaminar and reticular nuclei of the thalamus which, in turn, project diffusely to wide regions of the cortex including the frontal, parietal, temporal, and occipital cortices (Figure 14-3). Collaterals funnel into it not only from the long

Variations in the Alpha Rhythm
In humans, the frequency of the dominant EEG rhythm at rest varies with age. In infants, there is fast, beta-like activity, but the occipital rhythm is a slow 0.5-2-Hz pattern. During childhood this latter rhythm speeds up, and the adult alpha pattern gradually appears during adolescence. The frequency of the alpha rhythm is decreased by low blood glucose levels, low body temperature, low levels of adrenal glucocorticoid hormones, and high arterial partial pressure of CO2 (PaCO2). It is increased by the reverse conditions. Forced over-breathing to lower the PaCO2 is sometimes used clinically to bring out latent EEG abnormalities. The frequency and magnitude of the alpha rhythm is also decreased by metabolic and toxic encephalopathies including those due to hyponatremia and vitamin B12 deficiency.
The frequency of the alpha rhythm is reduced during acute intoxication with alcohol, amphetamines, barbiturates, phenytoin, and antipsychotics.

Propofol, a hypnotic/sedative drug, can induce a rhythm in the EEG that is analogous to the classic alpha rhythm.

Obstructive sleep apnea (OSA) is the most common cause of daytime sleepiness due to fragmented sleep at night; it affects about 24% of middle- aged men and 9% of women in the United States. Breathing ceases for more than 10 s during frequent episodes of obstruction of the upper airway (especially the pharynx) due to a reduction in muscle tone. The apnea causes brief arousals from sleep in order to reestablish upper airway tone. An individual with OSA typically begins to snore soon after falling asleep. The snoring gets progressively louder until it is interrupted by an episode of apnea, which is followed by a loud snort and gasp as the individual tries to breathe.
OSA is not associated with a reduction in total sleep time, but individuals with OSA experience a much greater time in stage 1 non-REM sleep (from an average of 10% of total sleep to 30-50%) and a marked reduction in slow-wave sleep (stages 3 and 4 non-REM sleep). The pathophysiology of OSA includes both a reduction in neuromuscular tone at the onset of sleep and a change in the central respiratory drive.

Sleepwalking (somnambulism), bed-wetting (nocturnal enuresis), and night terrors are referred to as parasomnias, which are sleep disorders associated with arousal from non-REM and REM sleep. Episodes of sleepwalking are more common in children than in adults and occur predominantly in males. They may last several minutes.
Somnambulists walk with their eyes open and avoid obstacles, but when awakened they cannot recall the episodes.

Positron emission tomography (PET) scans in REM sleep show increased activity in the pontine area, amygdala, and anterior cingulate gyrus, but decreased activity in the prefrontal and parietal cortex. Activity in visual association areas is increased, but activity is decreased in the primary visual cortex. This is consistent with increased emotion and operation of a closed neural system cut off from the areas that relate brain activity to the external world.

Erythropoietin is produced by interstitial cells in the peritubular capillary bed of the kidneys and by perivenous hepatocytes in the liver. It is also produced in the brain, where it exerts a protective effect against excitotoxic damage triggered by hypoxia; and in the uterus and oviducts, where it is induced by estrogen and appears to mediate estrogen-dependent angiogenesis.
The gene for the hormone has been cloned, and recombinant erythropoietin produced in animal cells is available for clinical use as epoetin alfa.
The recombinant erythropoietin is of value in the treatment of the anemia associated with kidney failure; 90% of the patients with end-stage renal disease who are undergoing dialysis are anemic as a result of erythropoietin deficiency. Erythropoietin is also used to stimulate red cell production in individuals who are banking a supply of their own blood in preparation for autologous transfusions during elective surgery (see Chapter 31).

Composition of normal human pancreatic juice.
Cations: Na+, K+, Ca2+, Mg2+ (pH approximately 8.0)
Anions: HCO3-, Cl-, SO42-, HPO42-
Digestive enzymes -95% of protein in juice)
Other proteins