Science And Biology

Human heart  Heart is blood pumping organ placed slightly toward left side in the middle of the thoracic cavity.It applies great pumping pressure on blood using strong cardiac muscles, making it to circulate through blood vessels  to every nook and corner of  body. It  keeps on working with out any rest through out life time. Heart is conical in shape with apex facing down wards and broad base directed upwards. It is protected on all sides by rib cage and by vertebral column on the back side. Heart is enclosed in double layered transparent thin sac called Pericardium. The space between two layers called  Pericardial space  is filled with  pericaridal fluid .Pericardium and pericardial fluid protect the heart from physical shocks. The human heart has four chambers, upper two atria and lower two ventricles.Internally four chambers are separated by   Septae .Right and left atria are separated by  Inter-auricular septum ....

Human eye  Human eye is highly developed photo sensory organ. About only 1/6 of the eye ball is out side and remaining part is enclosed in socket of skull. Eye ball is not a perfect sphere but is slightly protruding in the front. Human eye has highly evolved  stereoscopic   binocular vision  which is absent in most other animals.The front portion of eye is protected by upper and lower eye lid. Upper eye lid constantly is engaged in clearing of dust particles like wipers of  car`s wind shield. There are two  Lacrimal glands  whose secretions called tears keep the eye surface constantly moist. One Lacrimal gland is arranged toward upper right and one towards  caruncula . The lacrimal secretions also contain an antibacterial enzyme called  Lysozyme  which eliminates bacteria keeping eye surface healthy. Opening and closing of eye lids is involuntary and partly voluntary action. We show involuntary reflexes of closing eye lids, whe...

Human ear Human ear is auditory and balancing organ. It not only captures the sounds, but also helps in maintaining body balance and posture.The outer visible part of ear is called external ear or  Ear pinna . It is composed of flexible tissue called Cartilage.Ear pinna or auricle is characteristic feature of mammals. It is useful in animals like cat, dear, cow to localize the source of sounds. It acts as dish antenna to converge sound waves in to internal ear. Ear pinna and ear muscles are considered as vestigial organs in human, since they are useless. Ear can be divided into three parts namely  Outer ear, Middle ear, Inner ear . Outer ear Outer ear has visible fleshy flexible ear pinna and deep  external auditory canal .The  external auditory canal  is a slightly curved tube  and ends blindly at the  tympanic membrane  other wise called as ear drum. Auditory canal has lined ceruminous gland which produces a waxy secretion called...

Human digestive system The human digestive system starts with mouth and ends with anus.The  function of digestive system  starts with   intake food -Ingestion, Chewing and mixing of food with Saliva - Mastication,Swalloing of food -Deglutition, Break down of food in to simpler form - Digestion, Imbibition of digested food in to blood- Absorption, expulsion of undigested food- defecation.The part of digestive system which starts with mouth and ends with anus is also termed as Alimentary canal. Mouth Mouth encloses a cavity called Oral cavity  other wise called Buccal cavity. There are 32 teeth in mouth.  The human dental formula is 2/2,1/1,2/2,3/3. First four teeth  Incisors, next two canines, next four  pre-molar and last three molars.The last pair of molars are called wisdom teeth which appear at age of 20 years. The floor of buccal cavity has muscular organ called tongue. It has sensory papillae with taste buds and hence works as ...

Human brain     Human brain is one of the most complex and magnificent organs in the human body. Our brain gives us self consciousness and consciousness of our environment, processing a constant stream of sensory data.  The brain’s neurons record the memory of every event in our lives. It is the organ which coordinates several muscular moments, analyzes the streams data from sensory organs, controls secretions of glands,memorizes the past experiences, controls the emotions and thoughts with touch of judgement and intelligence. Every creative thought, feeling, and plan is developed by our brain. Brain is dome shaped mass of soft nervous tissue protected by bony case called  Cranium .It is command center of human nervous system. It receives information in the form of electrical and impulses, analyzes them and generates appropriate out put signal to the muscles.Human brain is largest in size in proportion to body  when compared to other animals.It ...

Human skin Human skin is outer covering of body which performs body`s vital functions of protection, sensation, excretion of sweat through sweat, glands, body  heat regulation (Temperature Homeostasis), storage  of fats and synthesis of Vitamin D.It is the largest sense organ with total area of about 1.5 Sq meters. It weighs 16% of body weight.Skin consists of several tightly arranged dead cells which are impermeable to water and microorganisms.Outer layer of skin consists of several layers  dead cells made of keratin protein. Skin on palms and foot souls is thick and devoid of hair follicles. Finger tips have patterns called finger prints which are highly unique to individual.Skin can be divided into three layers namely Epidermis, Dermis and Hypodermis. Epidermis Epidermis is avascular region that is it does not contain any blood vessels.It is composed of about 40 to 50 rows of cells called squamous epithelial cells (keratinocytes). Specialized pigment ...

Male reproductive system The male reproductive system is located in lower abdomen of males. It consists of  scrotum, testes, spermatic ducts,  glands, and penis.The function of male reproductive system is to produce millions of sperms within viscous fluid called semen and depositing it in to vagina, with the use of erectile organ called Penis.Males are driven by natural instincts to carry out this biological act as it is very essential for perpetuation of race.Testes also produces male sex hormone Testosterone which is responsible for development of secondary sexual characters in boys. Scrotum The scrotum is a sac-like organ made of skin and muscles that accommodates the testes. It is located below to the penis in the pubic region. The scrotum is made up two pouches with a testis located in each pouch. . When the testes become too warm to support spermatogenesis, the scrotum relaxes to move the testes away from the body’s heat.This mechanism maintains -...

Female reproductive system Female reproductive system is located in lower abdomen of women. It`s main function is to incubate the developing fetus and deliver baby into world. It also produces ova (female gamete) every 27-30 days associate with Menstrual cycle and produce couple of female sex  hormones which are required for secondary sexual characters, secretion of milk and pregnancy.The female reproductive organs can be subdivided into the internal and external genitalia .The internal genitalia are those organs that are within the true pelvis. These include the vagina, uterus, cervix, uterine tubes (oviducts or fallopian tubes), and ovaries. The external genitalia lie outside the true pelvis. These include the perineum, mons pubis, clitoris, urethral (urinary) meatus, labia majora and minora, vestibule, greater vestibular (Bartholin) glands, Skene glands, and periurethral area. External genitalia The vulva, also known as the pudendum, is a term used to describe thos...