Wednesday, May 25, 2011

Postnatal period


The period occuring after birth.

Infancy: refers to the earliest peroid of extrauterine life, roughly the first year after birth.

An infant aged 1 month or younger is called a Newborn or Neonate

Characteristics: Transition from intrauterine to extrauterine existence requires many critical changes, especially in the cardiovascular and respiratory system.If newborn infants survive the first crucial hours after birth,their chances of living are usually good.The body as whole grows particularly rapidly during infancy; total length increases by approximately one half and weight is usually tripled. By 1 year of age,most children have six to eight teeth.

Childhood : is the peroid from aprproximately 13 months until puberty (13months - 11 year)

Characteristics :The primary ( deciduous ) teeth continue to appear and are later replaced by the secondary ( permanent ) teeth. During early Childhood, there is active ossification (formation of bone ), but as the child becomes older, the rate of body growth slows down. Just before puberty, however, growth accelerates- the prepubertal growth spurt.

Puberty : Occurs usually between the ages of :-

Girls: 12-15 years
Boys: 13-16 years

Characteristics : During which secondary sexual characteristics develop and the capability of sexual reproduction is attained. The stages of pubertal development follow a consistent pattern and are defined by the appearance of secondary sexual characteristics (e.g., pubic hair development, Breasts in females, and growth of external genitalia in males). Puberty ends in females with the first menstrual period or menarche, the beginning of the menstrual cycles or periods. Puberty ends in males when sperms are produced.


Adolescence : is the period from approximately 11 - 19 years of age

Characteristics : Rapid Physical and Sexual maturation. It extends from the earliest signs of sexual maturity-puberty-until the attainment of adult physical, mental and emotional maturity. The ability to reproduce is achieved during adolescence. The general growth rate decelerates as this period terminates, but growth of some structures accelerates (e.g., female breasts and male genitalia).


Adulthood : attainment of full growth and maturity, is generally reached between the ages of 18 - 21 years.

Characteristics : Ossification and Growth are virtually completed during early adulthood (21-25 years). Thereafter, developmental changes occur very slowly.

Tuesday, May 24, 2011

Lymph Vessels and Nodes of Lung





Lymphatic System (in brief ):



Major structures

lymph vessels
lymph nodes
lymph fluid
tonsils

Also:

spleen
thymus

Functions of the Lymph System
  • lymph/o
  • drain fluid from tissue spaces and return to it to the blood
  • transport materials (nutrients, hormones and oxygen) to body cells
  • carry away waste products to the blood
  • transport lipids away from digestive system
  • control of infection
  • Lymph originates in blood plasma
  • Interstitial fluid
  • cleans and nourishes body tissues
  • collects cellular debris, bacteria
  • return to blood or lymph capillaries


Lymph Nodes

  • located in lymph vessels
  • small round or oval structures (filters)
  • depositories for cellular debris
  • bacteria and debris phagocytized
  • inside are masses of tissue which contain WBCs (lymphocytes)
  • almost always grouped 2 or 3 to 100
  • invading cells destroyed in nodes and often swell as an indicator of the disease process


Spleen

sac-like mass of lymphatic tissue
filter for lymph
phagocytic cells
hemolytic


Thymus

lymphatic tissue
mediastinum
primary role: changes lymphocytes to T cells for cellular immunity

Sunday, May 22, 2011

Normal Values and Concentrations (Respiratory System)





















The Normal Pleural pressure at the begining of inspiration is about - 5 cm of water.

During Normal inspiration ,Expansion of the chest cage pulls outward on the lungs with greater force and creates more negative pressure, to an average of about - 7.5 cm of water.

Alveolar pressure is the pressure of the air inside the lung alveoli.

During Normal inspiration, Alveolar pressure decreases to about -1 cm of water.

Compliance of the Lungs:

The total compliance of both lungs together in the normal adult human being averages about 200ml of air per cm of water transpulmonary pressure.

That is, everytime the transpulmonary pressure increases 1 cm of water, the Lung volume after 10 to 20 seconds, will expand 200mls.

During normal quiet respiration, only 3 to 5 percent of the total energy expended by the body is required for pulmonary ventilation.But 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 pulmonary compliance.

Pulmonary Volumes and Capacities:

(Vt)Tidal volume= 500 ml
(IRV)Inspiratory reserve volume = 3000 ml
(ERV)Expiratory reserve volume = 1100ml
(RV)Residual volume = 1200ml

Inspiratory capacity (IC) = IRV(Inspiratory reserve volume) + Vt (Tidal Volume)=3000ml + 500ml = 3500ml

VC= IRV + Vt + ERV
VC= IC + ERV
TLC= VC + RV
TLC IC + FRC
FRC= ERV + RV

RV= FRC - ERV

TLC= FRC + IC

The Normal respiratory rate is about 12 breaths per minute.
Therefore, the minute respiratory volume averages about 6L/min.
A person can live for a short period with a minute respiratory volume as low as 1.5L/min and a respiratory rate of only 2 -4 breathes per minute.

The Normal Dead space air in a young adult man is about 150 mls.This increases slightly with age.

Interrelations Between Interstitial Fluid pressure and Other Pressure in the Lung:

Forces tending to cause movement of fluid outward from the capillaries and into the pulmonary interstitium:

Capillary pressure 7mmHg
Interstital fluid colloid osmotic pressure 14mmHg
Negative interstital fluid pressure 8mmHg

TOTAL OUTWARD FORCE = 29mmHg

Forces tending to cause absorption of fluid into the capillaries:

Plasma colloid osmotic pressure 28mmHg

TOTAL INWARD FORCE = 28mmHg

MEAN FILTRATION PRESSURE:


TOTAL OUTWARD FORCE = 29mmHg - TOTAL INWARD FORCE = 28mmHg = +1

Alveoli consists of :

1) type I alveolar cells (95%), thin
2) type II alveolar cells (5%), secrete surfactant.
3) macrophages (dust cells), defense

Pleura :

The parietal and visceral pleura, are separated by 10–24 ยตm between the two surfaces.
This space is usually filled with a very small amount of fluid 7 – 10 ml. However, large amounts upto 4–5 litres in an adult of fluid can accumulate in the pleural space under pathological conditions.

Sunday, May 15, 2011

Normal Values and Concentrations (Blood)


The mean diameter of RBCs is 7.8um and a thickness of 2.5um

Plasma Proteins

Include:
Albumin (60%)
Globulins (36%) (Antibodies & transport proteins)
Clotting Proteins (4%)
Enzymes & Hormones

Hematocrit (the percentage of Blood that is cells--normally, 40-45%) and Quantity of hemoglobin in each respective cell are normal,the Whole Blood of Men contains an average of 15 grams of hemoglobin per 100 ml of cells; for Women it contains an average of 14 grams per 100ml

In Normal men Average number of RBCs per cubic millimeter is 5,200,000
In Normal women ,it is 4,700,000

The Adult Human being has about 7000 white blood cells per microliter of Blood (in comparison with 5 Million RBCs): Of the total WBCs, the normal percentages of the different types approximately the following:

Polymorphonuclear neutrophils 62.0%
Polymorphonuclear eosinophils 2.3%
Polymorphonuclear basophils 0.4%
Monocytes 5.3%
Lymphocytes 30.0%

Platelets (thrombocytes) : Normal concentration in the blood is between 150,000-300,000 per microliter.

The Clot begins to develop in 15-20 seconds if the trauma to the vascular wall has been severe, and in 1-2 minutes if the trauma has been minor.

Serum cannot clot because it lacks these factors.

Decreased Prothrombin , Factor VII , Factor IX and Factor X Caused by Vitamin K deficiency ( also for Protein C)

Bleeding ordinary lasts for 1-6 minutes.

The action of Heparin lasts about 1.5-4 hours.

Normal clotting time is 6-10 minutes.

The Normal prothrombin time is about 12 seconds.

Comparison between Neutrophils and Macrophages:

Neutrophils :A single neutrophil can usually phagocytize 3-20 bacteria before itself becomes inactivated or dies.

Macrophages:They are much more powerful phagocytes than neutrophils often capable of phagocytizing as many as 100 bacteria.

Stimulation of Growth and Proliferation of Cytotoxic and Suppressor T cells:

The Lymphokines interleukin-2 has an especially strong stimulatory effect in causing growth and proliferation of both Cytotoxic and Suppressor T cells.

Stimulation of Growth and Differentiation to Form Plasma cells and Antibodies:

Especially interleukin 4,5 and 6 have such potent effects on the B cells that they have been called B-cell stimulating or B cell growth factors.

Relative Frequencies of Different Blood Types:

O-----------47%
A-----------41%
B-----------9%
AB----------3%

RBC's normally circulate an average of 120 days before being destroyed

Normal adult human hemoglobins

Form:HbA Chain Composition: a2b2 Fraction of total Hemoglobin:90%

Form:HbF Chain Composition:a2gamma-2 Fraction of total Hemoglobin:less than 2%

Form:HbA2 Chain Composition:a2sigma-2 Fraction of total Hemoglobin:2-5%

Form:HbA1c Chain Composition:a2b2-glucose Fraction of total Hemoglobin:3-9%

Saturday, May 14, 2011

Skin histology


The skin is the heaviest single organ of the body, accounting for about 16% of total body weight.
It is composed of the EPIDERMIS, DERMIS, HYPODERMIS .

The junction of dermis and epidermis is irregular, and projections of the dermis called PAPILLAE interdigitate with evaginations of the epidermis known as EPIDERMAL RIDGES.
Epidermal derivatives include HAIRS, NAILS, AND SEBACEOUS AND SWEAT GLANDS.
Beneath the dermis lies the hypodermis (Gr. hypo, under, + derma, skin), or subcutaneous tissue, a loose connective tissue that may contain a pad of adipose cells. The hypodermis, which is not considered part of the skin, binds skin loosely to the subjacent tissues and corresponds to the superficial fascia of gross anatomy.


The junction of dermis and epidermis is irregular, and projections of the dermis called papillae interdigitate with evaginations of the epidermis known as epidermal ridges. In three dimensions, these interdigitations may be of the peg-and-socket variety (thin skin) or formed of ridges and grooves (thick skin). Epidermal derivatives include HAIRS, NAILS, AND SEBACEOUS AND SWEAT GLANDS. Beneath the dermis lies the hypodermis (Gr. hypo, under, + derma, skin), or subcutaneous tissue, a loose connective tissue that may contain a pad of adipose cells, the panniculus adiposus. The hypodermis, which is not considered part of the skin, binds skin loosely to the subjacent tissues and corresponds to the superficial fascia of gross anatomy.





STRATUM BASALE (STRATUM GERMINATIVUM)

The stratum basale consists of a single layer of basophilic columnar or cuboidal cells resting on the basement membrane at the dermale-pidermal junction .Desmosomes bind the cells of this layer together in their lateral and upper surfaces.
The stratum basale, containing stem cells, is characterized by intense mitotic activity and is responsible, in conjunction with the initial portion of the next layer, for constant renewal of epidermal cells.
All cells in the stratum basale contain intermediate keratin filaments about 10 nm in diameter. As the cells progress upward, the number of filaments increases until they represent half the total protein in the stratum corneum.


STRATUM SPINOSUM

The stratum spinosum consists of cuboidal, or slightly flattened, cells with a central nucleus and a cytoplasm whose processes are filled with bundles of keratin filaments. These bundles converge spiny projections .The cells of this layer are firmly bound together by the filament-filled cytoplasmic spines and desmosomes that punctuate the cell surface, providing a spine-studded appearance. These keratin bundles, visible under the light microscope, are called tonofilaments; they end at and insert into the cytoplasmic densities of the desmosomes. The filaments play an important role in maintaining cohesion among cells and resisting the effects of abrasion. The epidermis of areas subjected to continuous friction and pressure (such as the soles of the feet) has a thicker stratum spinosum with more abundant tonofilaments and desmosomes.


Stratum spinosum of the skin from the sole of the foot (thick skin) showing the spiny projections that strongly bind the cells of this layer together to resist abrasion.


STRATUM GRANULOSUM

The stratum granulosum consists of three to five layers of flattened polygonal cells whose cytoplasm is filled with coarse basophilic granules ,called keratohyalin granules. The proteins of these granules contain a phosphorylated histidine-rich protein as well as proteins containing cystine. The numerous phosphate groups account for the intense basophilia of keratohyalin granules, which are not surrounded by a membrane.


Another characteristic structure in the cells of the granular layer of epidermis that can be seen with the electron microscope is the membrane-coated lamellar granule, a small ovoid or rodlike structure containing lamellar disks that are formed by lipid bilayers. These granules fuse with the cell membrane and discharge their contents into the intercellular spaces of the stratum granulosum, where they are deposited in the form of sheets containing lipid. The function of this extruded material is similar to that of intercellular cement in that it acts as a barrier to penetration by foreign materials and provides a very important sealing effect in the skin. Formation of this barrier, which appeared first in reptiles, was one of the important evolutionary events that permitted development of terrestrial life.

STRATUM LUCIDUM

More apparent in thick skin, the stratum lucidum is a translucent, thin layer of extremely flattened eosinophilic epidermal cells .The organelles and nuclei are no longer evident, and the cytoplasm consists primarily of densely packed keratin filaments embedded in an electron-dense matrix. Desmosomes are still evident between adjacent cells.

STRATUM CORNEUM

The stratum corneum consists of 15-20 layers of flattened nonnucleated keratinized cells whose cytoplasm is filled with a birefringent filamentous scleroprotein, keratin.
After keratinization, the cells consist of only fibrillar and amorphous proteins and thickened plasma membranes; they are called HORNY CELLS. During keratinization, lysosomal hydrolytic enzymes play a role in the disappearance of the cytoplasmic organelles. These cells are continuously shed at the surface of the stratum corneum.
This description of the epidermis corresponds to its most complex structure in areas where it is very thick, as on the soles of the feet. In thin skin, the stratum granulosum and the stratum lucidum are often less well developed, and the stratum corneum may be quite thin .




CLINICAL:

In PSORIASIS, a common skin disease, there is an increase in the number of proliferating cells in the stratum basale and the stratum spinosum as well as a decrease in the cycle time of these cells. This results in greater epidermal thickness and more rapid renewal of epidermis.



In bullous pemphigoid and related disorders, the affected patient has an antibody which reacts against a specific antigen (BPAG) located in the hemidesmosomes and lamina lucida; an antigen-antibody reaction occurs triggering a sequence of changes damaging the basement membrane and leading to separation of the epidermis and blistering.



Section of the stratum spinosum showing the localized deposits of melanin covering the cell nuclei. Melanin protects the DNA from the UV radiation of the sun. This explains why people with light skin have a higher incidence of skin cancer than people with dark skin. The highest concentration of melanin occurs in the cells that are more deeply localized; these cells divide more actively. (The DNA of cell populations that multiply more actively is particularly sensitive to harmful agents.)










Saturday, May 7, 2011

Menstrual Cycle

The Physiological Phenomenon for which the Human Race Exists as it does Today


Menstrual cycle

The physiological phenomenon in which the unused endometrium is shed and voided from the body as the menses or period or menstrual flow.
This term was derived in the context of human females who happen to cycle in about the same length of time as a lunar month, it is also applied to other species whose cycles are not one month long.


Human females are somewhat unusual

Females of most species are only receptive around the time of ovulation (release of a fertile egg)
A human female is more receptive around the time of ovulation
But that is not the only time she is receptive
Human females generally are receptive to sexual activity throughout their cycles


The average menstrual cycle in humans ranges about 20 to 40 days in length, with a statistical average of about 28 to 29 days.

By convention, the first day of a woman’s period is considered to be day 1 of her cycle.

The first 3 to 7 days are generally the menstrual flow phase and during this time, all hormones involved are at low levels.


Five hormones involved in controlling the female cycle

Gonadotropin releasing hormone (GnRH) secreted by the hypothalamus
Follicle-stimulating hormone (FSH) &
Lutenizing hormone (LH) secreted by the pituitary gland
Estrogen &
Progesterone secreted by ovaries




The first half of a woman’s cycle is the proliferative phase (follicular phase), during which the endometrium starts to thicken.

The pituitary secretes FSH which causes (usually one) follicle to mature and the ovaries to secrete estrogen.
The ovarian estrogen secretion gradually increases until just prior to ovulation.
This gradually supresses secretion of FSH and stimulates the hypothalamus to secrete a larger amount of GnRH which, in turn, triggers the pituitary to secrete a burst of LH, causing ovulation.


During the proliferative phase, a woman’s body temperature is low.

Sometimes there is a slight rise near the end of the phase during the pre-ovulatory burst of LH before it dips again at ovulation.

Throughout this phase, the cervical mucus becomes progressively clearer and thinner

Ovulation

Day 14 of an average 28-day cycle
In response to the surge of LH the rupture of the follicle and release of the egg
LH stimulates the remaining follicle cells to form a corpus luteum after ovulation
Sharp drop in the woman’s body temperature
cervical mucus becomes very thin and clear and forms “threads”

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