Spleen Disambiguation

The spleen, an organ found in virtually all vertebrate animals, satiates important roles in regards to red blood cells and the immune system^[1] Located in the left upper quadrant of the abdomen, It removes old red blood cells, holds a reserve in case of hemorrhagic shock in some animals such as horses, but not humans), and recycles iron while simultaneously removing from the blood circulation antibody-coated bacteria and antibody-coated blood cells.<.^[2] It synthesizes antibodies in its white pulp ref name="Mebius"/>^[3] Recently, it has been found to contain, in its reserve, half the body's monocytes , which is located in its red pulp, that, upon moving to injured tissue such as the heart, turns into dendritic cells and macrophages while aiding wound healing.^[4][5][6] It is one of the centers aiding to the activity of the reticuloendothelial system, and can be considered analogous to a large lymph node; the spleens absence leads to a predisposition to certain infections.

The celiac artery and its branches.	The celiac artery and its branches.	Horizontal disposition of the peritoneum in the upper part of the abdomen.	Transverse section through the middle of the first lumbar vertebra.
The duodenum and pancreas.	The visceral surface of the spleen.	Transverse section of the spleen, showing the trabecular tissue and the splenic vein and its tributaries.	Transverse section of the human spleen, showing the distribution of the splenic artery and its branches.
Section of the spleen, showing the termination of the small blood vessels.	Back of lumbar region, showing surface markings for kidneys, ureters, and spleen.	Side of thorax, showing surface markings for bones, lungs (purple), pleura (blue), and spleen (green).	Lymphatic system

Reproductive system

This article is about sexual reproductive systems. For the reproductive systems of asexual organisms, see Asexual reproduction.

The reproductive system or genital system is a system of organs within an organism which work together for the purpose of reproduction Which is when a woman and a man get freaky then the woman gets knocked up in the end. Many non-living substances such as fluids, hormones, and pheromones are also important accessories to the reproductive system.^[1] Unlike most organ systems, the sexes of differentiated species often have significant differences. These differences allow for a combination of genetic material between two individuals, which allows for the possibility of greater genetic fitness of the offspring.^[2]

The major organs of the human reproductive system include the external genitalia (penis and vulva) as well as a number of internal organs including the gamete producing gonads (testicles and ovaries). Diseases of the human reproductive system are very common and widespread, particularly communicable sexually transmitted diseases.^[3]

Most other vertebrate animals have generally similar reproductive systems consisting of gonads, ducts, and openings. However, there is a great diversity of physical adaptations as well as reproductive strategies in every group of vertebrates.

pictorial illustration of the human male reproductive system.

• 1 Human reproductive system
  • 1.1 Male reproductive system (penis)
  • 1.2 Female reproductive system
  • 1.3 Production of gametes
  • 1.4 Development of the reproductive system
  • 1.5 Diseases of the human reproductive system
    • 1.5.1 Examples of congenital abnormalities
    • 1.5.2 Examples of cancers
    • 1.5.3 Examples of infections
    • 1.5.4 Examples of functional problems
• 2 Other vertebrates
  • 2.1 Mammals
  • 2.2 Birds
  • 2.3 Reptiles
  • 2.4 Amphibians
  • 2.5 Fish
• 3 Invertebrates
  • 3.1 Cephalopods
• 4 See also
• 5 References

Human reproduction takes place as internal fertilization by sexual intercourse. During this process, the erect penis of the male is inserted into the female's vagina until the male ejaculates semen, which contains sperm, into the female's vagina. The sperm then travels through the vagina and cervix into the uterus or fallopian tubes for fertilization of the ovum. Upon successful fertilization and implantation, gestation of the foetus then occurs within the female's uterus for approximately nine months, this process is known as pregnancy in humans. Gestation ends with birth, the process of birth is known as labor. Labor consists of the muscles of the uterus contracting, the cervix dilating, and the baby passing out the vagina. Human's babies and children are nearly helpless and require high levels of parental care for many years. One important type of parental care is the use of the mammary glands in the female breasts to nurse the baby.

Male reproductive system (penis)

Main article: Male reproductive system (human)

Partially shaved erect male genitalia. 1. Testicles, 2. Epididymis, 3. Corpus cavernosa, 4. Foreskin, 5. Frenulum, 6. Urethral opening , 7. Glans penis, 8. Corpus spongiosum, 9. Penis, 10. Scrotum.

The human male reproductive system is a series of organs located outside of the body and around the pelvic region of a male that contribute towards the reproductive process. The primary direct function of the male reproductive system is to provide the male gamete or spermatozoa for fertilization of the ovum.

The major reproductive organs of the male can be grouped into three categories. The first category is sperm production and storage. Production takes place in the testes which are housed in the temperature regulating scrotum, immature sperm then travel to the epididymis for development and storage. The second category are the ejaculatory fluid producing glands which include the seminal vesicles, prostate, and the vas deferens. The final category are those used for copulation, and deposition of the spermatozoa (sperm) within the female, these include the penis, urethra, vas deferens, and Cowper's gland.

Major secondary sexual characteristics include: larger, more muscular stature, deepened voice, facial and body hair, broad shoulders, and development of an adam's apple. An important sexual hormone of males is androgen, and particularly testosterone.

Female reproductive system

Main article: Female reproductive system (human)

Photograph of the vulva. 1. Pubic hair (shaved), 2.Clitoral hood, 3. Clitoris, 4. Labia majora, 5. Labia minora (enclosing the Vaginal Opening), 6. Perineum.

The human female reproductive system is a series of organs primarily located inside of the body and around the pelvic region of a female that contribute towards the reproductive process. The human female reproductive system contains three main parts: the vagina, which acts as the receptacle for the male's sperm, the uterus, which holds the developing fetus, and the ovaries, which produce the female's ova. The breasts are also an important reproductive organ during the parenting stage of reproduction.

The vagina meets the outside at the vulva, which also includes the labia, clitoris and urethra; during intercourse this area is lubricated by mucus secreted by the Bartholin's glands. The vagina is attached to the uterus through the cervix, while the uterus is attached to the ovaries via the fallopian tubes. At certain intervals, typically approximately every 28 days, the ovaries release an ovum, which passes through the fallopian tube into the uterus. The lining of the uterus, called the endometrium, and unfertilized ova are shed each cycle through a process known as menstruation.

Major secondary sexual characteristics include: a smaller stature, a high percentage of body fat, wider hips, development of mammary glands, and enlargement of breasts. Important sexual hormones of females include estrogen and progesterone.

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Introduction to ears and hearing

The ear is the organ that detects sound. The vertebrate ear shows a common biology from fish to humans, with variations in structure according to order and species. It not only acts as a receiver for sound, but plays a major role in the sense of balance and body position. The ear is part of the auditory system.

The word "ear" may be used correctly to describe the entire organ or just the visible portion. In most animals, the visible ear is a flap of tissue that is also called the pinna. The pinna may be all that shows of the ear, but it serves only the first of many steps in hearing and plays no role in the sense of balance. In people, the pinna is often called the auricle. Vertebrates have a pair of ears, placed symmetrically on opposite sides of the head. This arrangement aids in the ability to localize sound sources.

The outer part of the ear collects sound. That sound pressure is amplified through the middle portion of the ear and, in land animals, passed from the medium of air into a liquid medium. The change from air to liquid occurs because air surrounds the head and is contained in the ear canal and middle ear, but not in the inner ear. The inner ear is hollow, embedded in the temporal bone, the densest bone of the body. The hollow channels of the inner ear are filled with liquid, and contain a sensory epithelium that is studded with hair cells. The microscopic "hairs" of these cells are structural protein filaments that project out into the fluid. The hair cells are mechanoreceptors that release a chemical neurotransmitter when stimulated. Sound waves moving through fluid push the filaments; if the filaments bend over enough it causes the hair cells to fire. In this way sound waves are transformed into nerve impulses. In vision, the rods and cones of the retina play a similar role with light as the hair cells do with sound. The nerve impulses travel from the left and right ears through the eighth cranial nerve to both sides of the brain stem and up to the portion of the cerebral cortex dedicated to sound. This auditory part of the cerebral cortex is in the temporal lobe.

The part of the ear that is dedicated to sensing balance and position also sends impulses through the eighth cranial nerve, the VIIIth nerve's Vestibular Portion. Those impulses are sent to the vestibular portion of the central nervous system. The human ear can generally hear sounds with frequencies between 20 Hz and 20 kHz (the audio range). Although the sensation of hearing requires an intact and functioning auditory portion of the central nervous system as well as a working ear, human deafness (extreme insensitivity to sound) most commonly occurs because of abnormalities of the inner ear, rather than the nerves or tracts of the central auditory system.

Rhinoplasty Surgical procedures and types

Rhinoplasty (Greek: Rhinos, "Nose" + Plassein, "to shape") is a surgical procedure which is usually performed by either an otolaryngologist-head and neck surgeon, maxillofacial surgeon, or plastic surgeon in order to improve the function (reconstructive surgery) or the appearance (cosmetic surgery) of a human nose. Rhinoplasty is also commonly called "nose reshaping" or "nose job". Rhinoplasty can be performed to meet aesthetic goals or for reconstructive purposes to correct trauma, birth defects or breathing problems. Rhinoplasty can be combined with other surgical procedures such as chin augmentation to enhance the aesthetic results.

Patient, three days post-op. Procedures included dorsal bone reduction and re-setting and refinement of nasal tip cartilage. The typical orbital discoloration is also present due to trauma and disruption of blood vessels around the eyes. Also present is a splint.

Skin incision for an open rhinoplasty. The incision may be “v-shaped” or a “stair-step” shaped incision. This aids the surgeon in attaining a precise closure and for camouflaging the resulting scar.

Exposing the cartilages inside the nose

Planning excision of a nasal hump

One technique to narrow the nasal tip

Designing the cuts in the nasal bones

At the end of the rhinoplasty

Reconstructive rhinoplasty refers to restoring the normal shape and function of the nose following damage from a traumatic accident, autoimmune disorder, intra-nasal drug abuse, previous injudicious cosmetic surgery, cancer involvement, or congenital abnormality. Rhinoplasty can restore skin coverage, recreate normal contours, and re-establish nasal airflow. To improve nasal breathing function, a septoplasty may also be performed. If there is turbinate hypertrophy, an inferior turbinectomy can be performed.

Rhinoplasty may be sought in the aftermath of traumatic deformity. Traumatic accidents are the most common cause of nasal deformity. Typically the nasal bones are broken and displaced. Occasionally, the nasal cartilages are disrupted or displaced, and in the worst cases the nasal dorsum is collapsed. Rhinoplasty allows shaving of the displaced bony humps, and re-alignment of the nasal bones after they are cut. When cartilage is disrupted, stitching of the cartilage for re-suspension, or use of cartilage grafts to camouflage depressions allows re-establishment of normal nasal contour. When the dorsum is collapsed, grafts of rib cartilage, ear cartilage, or cranial bone can be used to restore continuity to the dorsum. Although synthetic implants are also available for augmenting the nasal dorsum, cartilage or bone graft from the patient’s own body poses fewer risks of infection or rejection.

Human Gastrointestinal Tract

Upper and Lower human gastrointestinal tract

The human gastrointestinal tract (GI tract), digestive tract, guts or gut is the system of organs within humans that takes in food, digests it to extract energy and nutrients, and expels the remaining matter. The major functions of the gastrointestinal tract are ingestion, digestion, absorption, and defecation.

In an adult male human, the GI tract is approximately 6.5 metres (20 ft) long and consists of the upper and lower GI tracts. The tract may also be divided into foregut, midgut, and hindgut, reflecting the embryological origin of each segment of the tract.

The upper Gastrointestinal tract consists of the mouth, pharynx, esophagus, stomach, and duodenum proximal to the ligament of Treitz (or the Suspensory muscle of the duodenum).

• The mouth (or buccal cavity) contains the openings of the salivary glands; the tongue; and the teeth.
• Behind the mouth lies the pharynx which prevents food from entering the voice box and leads to a hollow muscular tube, the esophagus.
• Peristalsis takes place, which is the contraction of muscles to propel the food down the esophagus which extends through the chest and pierces the diaphragm to reach the stomach.
  

• Small intestine, two of the three parts:
  • Duodenum - Here the digestive juices from pancreas and liver mix together
  • Jejunum - It is the midsection of the intestine, connecting Duodenum to Ileum.
  • Ileum - It has villi in where all soluble molecules are absorbed into the blood.
• Large intestine, which has three parts:
  • Cecum (the vermiform appendix is attached to the cecum).
  • Colon (ascending colon, transverse colon, descending colon and sigmoid flexure)
  • Rectum
    

Gallbladder

The gallbladder (or cholecyst or gall bladder) is a small non-vital organ that aids in the digestive process and stores bile produced in the liver.
The gallbladder is a hollow organ that sits in a concavity of the liver known as the gallbladder fossa. In adults, the gallbladder measures approximately 8 cm in length and 4 cm in diameter when fully distended.^[2] It is divided into three sections: fundus, body, and neck. The neck tapers and connects to the biliary tree via the cystic duct, which then joins the common hepatic duct to become the common bile duct.

• The gallbladder has a simple columnar epithelial lining characterized by recesses called Aschoff's recesses, which are pouches inside the lining.
• Over the epithelium there is a layer of connective tissue (lamina propria).
• Above the connective tissue is a wall of smooth muscle (muscularis externa) that contracts in response to cholecystokinin, a peptide hormone secreted by the duodenum.
• There is, in essence, no submucosa separating the connective tissue from serosa and adventitia, but there is a thin lining of muscular tissue to prevent infection.

1. ^ Ginsburg, Ph.D., J.N. (2005-08-22). "Control of Gastrointestinal Function". in Thomas M. Nosek, Ph.D.. Gastrointestinal Physiology. Essentials of Human Physiology. Augusta, Georgia, United State: Medical College of Georgia. pp. p. 30. http://www.lib.mcg.edu/edu/eshuphysio/program/section6/6ch2/6ch2line.htm. Retrieved 2007-06-29.
2. ^ Jon W. Meilstrup (1994). Imaging Atlas of the Normal Gallbladder and Its Variants. Boca Raton: CRC Press. pp. 4. ISBN 0-8493-4788-2.
3. ^ "Slide 5: Gall Bladder". JayDoc HistoWeb. University of Kansas. http://www.kumc.edu/instruction/medicine/anatomy/histoweb/epithel/epith05.htm. Retrieved 2007-06-29.
4. ^ Romer, Alfred Sherwood; Parsons, Thomas S. (1977). The Vertebrate Body. Philadelphia, PA: Holt-Saunders International. p. 355. ISBN 0-03-910284-X.

Anatomy of cells

Diagram of a typical prokaryotic cell

The prokaryote cell is simpler, and therefore smaller, than a eukaryote cell, lacking a nucleus and most of the other organelles of eukaryotes. There are two kinds of prokaryotes: bacteria and archaea; these share a similar overall structure.

A prokaryotic cell has three architectural regions:

• on the outside, flagella and pili project from the cell's surface. These are structures (not present in all prokaryotes) made of proteins that facilitate movement and communication between cells;
• enclosing the cell is the cell envelope – generally consisting of a cell wall covering a plasma membrane though some bacteria also have a further covering layer called a capsule. The envelope gives rigidity to the cell and separates the interior of the cell from its environment, serving as a protective filter. Though most prokaryotes have a cell wall, there are exceptions such as Mycoplasma (bacteria) and Thermoplasma (archaea). The cell wall consists of peptidoglycan in bacteria, and acts as an additional barrier against exterior forces. It also prevents the cell from expanding and finally bursting (cytolysis) from osmotic pressure against a hypotonic environment. Some eukaryote cells (plant cells and fungi cells) also have a cell wall;
• inside the cell is the cytoplasmic region that contains the cell genome (DNA) and ribosomes and various sorts of inclusions. A prokaryotic chromosome is usually a circular molecule (an exception is that of the bacterium Borrelia burgdorferi, which causes Lyme disease). Though not forming a nucleus, the DNA is condensed in a nucleoid. Prokaryotes can carry extrachromosomal DNA elements called plasmids, which are usually circular. Plasmids enable additional functions, such as antibiotic resistance.

Eukaryotic cells are about 15 times the size of a typical prokaryote and can be as much as 1000 times greater in volume. The major difference between prokaryotes and eukaryotes is that eukaryotic cells contain membrane-bound compartments in which specific metabolic activities take place. Most important among these is the presence of a cell nucleus, a membrane-delineated compartment that houses the eukaryotic cell's DNA. It is this nucleus that gives the eukaryote its name, which means "true nucleus." Other differences include:

• The plasma membrane resembles that of prokaryotes in function, with minor differences in the setup. Cell walls may or may not be present.
• The eukaryotic DNA is organized in one or more linear molecules, called chromosomes, which are associated with histone proteins. All chromosomal DNA is stored in the cell nucleus, separated from the cytoplasm by a membrane. Some eukaryotic organelles such as mitochondria also contain some DNA.
• Many eukaryotic cells are ciliated with primary cilia. Primary cilia play important roles in chemosensation, mechanosensation, and thermosensation. Cilia may thus be "viewed as sensory cellular antennae that coordinate a large number of cellular signaling pathways, sometimes coupling the signaling to ciliary motility or alternatively to cell division and differentiation."^[7]
• Eukaryotes can move using motile cilia or flagella. The flagella are more complex than those of prokaryotes.