viernes, 2 de diciembre de 2011

domingo, 5 de junio de 2011

Female Reproductive System

The female reproductive system is a collection of organs and other structures located primarily in the pelvic region. Most of the structures are inside the body. The female reproductive system has several functions:
• producing eggs, which are female gametes
• secreting female sex hormones
• receiving sperm during sexual intercourse
• supporting the development of a fetus
• delivering a baby during birth
• breastfeeding a baby after birth
During puberty, a girl develops into a sexually mature woman, capable of producing eggs and reproducing.
Sexual Development in Females
Like baby boys, baby girls are born with all their reproductive organs present but immature and unable to function. Female reproductive organs grow very little during childhood. They begin to grow rapidly and to mature during puberty.
Changes of Puberty
Puberty in girls differs from puberty in boys in several ways, including when it begins, how long it lasts, and the hormones involved. Girls begin puberty a year or two earlier than boys, and they complete puberty in about four years instead of six. In females, the major sex hormone is estrogen rather than testosterone.
During puberty, estrogen promotes growth and other physical changes in females. For example, estrogen stimulates growth of the breasts and uterus. It also stimulates development of bones and contributes to the adolescent growth spurt in height.
Physical Changes in Females During Puberty
Changes in Reproductive Organs
Ovaries and follicles grow
Uterus grows and endometrium thickens
Other reproductive structures grow
Menstrual cycle begins
Other Physical Changes
Breasts develop
Long bones grow and mature
Pubic hair grows
Underarm hair grows
Body fat increases
Apocrine sweat glands develop
Pelvis widens
Mature reproductive organs are primary sex characteristics. Other changes, such as growth of pubic hair, lead to traits that are secondary sex characteristics.
Female Reproductive Organs
Only a few of the female reproductive structures are external to the body. All the main reproductive organs are internal.
External Organs
The external female reproductive structures are referred to collectively as the vulva. They include the mons pubis, the labia (majora and minora) and the clitoris. The labia are the “lips” of the vulva. They protect the vagina and urethra, both of which have openings in the vulva. The mons pubis consists of fatty tissue covering the pubic bone. It protects the pubic bone and vulva from injury. The clitoris, located between the labia minora at their upper end, is a small protrusion that corresponds to the penis in the male. The clitoris, like the penis, is very sensitive to sexual stimulation and can become erect.
Internal Organs
The internal female reproductive organs include the vagina, uterus, fallopian tubes, and ovaries.
The vagina is a cylinder-shaped organ. One end of the vagina opens at the surface of the body. The other end joins with the uterus. During sexual intercourse, sperm may deposited in the vagina. The sperm move through the vagina and into the uterus. During birth, a baby passes from the uterus through the vagina to leave the body.
The uterus is a hollow organ with muscular walls. The narrow part of the uterus where it connects with the vagina is called the cervix. The uterus is where a baby develops until birth. The walls of the uterus expand as the baby grows. The muscular walls of the uterus push the baby out during birth.
The two ovaries are small, oval organs on opposite sides of the uterus. Each ovary contains thousands of eggs. The eggs do not fully develop until a female has gone through puberty. About once a month, an egg completes its development and is released by the ovary. The ovaries also secrete estrogen.
The two Fallopian tubes are narrow passages that open off the uterus. Each tube reaches one of the ovaries. However, the tubes are not attached to the ovaries.

The Male Reproductive System

The male reproductive system is a collection of organs and other structures in the pelvic region. Most of the structures are located outside the body. The male reproductive system has two major functions: producing sperm and secreting testosterone. Sperm are male gametes. Testosterone is the main sex hormone in males. You read about Testosterona in the posts about endocrine system.
Sexual Development in Males
All the reproductive organs are present by birth. However, they are immature and unable to function. The reproductive organs grow very little during childhood and do not mature until puberty.
Puberty is the period during which humans become sexually mature. In the United States, boys generally begin puberty at about age 12 years. The testes produce testosterone that promotes most of the physical changes of puberty
Changes in Males During Puberty
Changes in Reproductive Organs
Testes grow larger Penis grows longer
Other reproductive structures grow Sperm production begins
Other Physical Changes
Pubic hair grows
Facial and body hair grow
Bone density increases
Long bones grow
Muscle mass and strength increase
Bones in face grow
Adam’s apple grows
Apocrine sweat glands develop
Shoulders widen
Voice deepens
Changes in the reproductive organs are called primary sex characteristics. Other changes, that are not directly related to reproduction are called secondary sex characteristics.
Male Reproductive Organs
The male reproductive organs include the penis, testes, and epididymis. Several ducts and glands are also parts of the male reproductive system. These organs are shown in Figure.
The penis is a cylinder-shaped organ. It is the copulatory organ. It contains the urethra. The urethra is a tube that carries urine – excretory system- out of the body and also the sperm – reproductive system-.
The two testes or testicles are the male gonads. They are egg-shaped organs. Their functions are to produce sperm and to secrete testosterone. The testes are contained in the scrotum. As you can see from Figure, the scrotum is a sac that hangs down outside the body. By hanging away from the body, the testes keep sperm at a temperature lower than normal body temperature. The lower temperature is needed for sperm production.
The epididymis is a tube that is about 6 meters long in adults. It is tightly coiled, so it fits inside the scrotum. It rests on top of the testes. The epididymis is where sperm mature. The epididymis also stores sperm until they leave the body.
Other parts of the male reproductive system include the vas deferens that carries sperm from the epididymis to the urethra. The main glands are the prostate and the seminal vesicles. They secrete substances that become part of semen.
Semen is a milky liquid that is ejaculated from the urethra. Semen contains secretions from the glands as well as sperm. The secretions control pH and provide the sperm with nutrients for energy.


We are going to begin with the most important concepts of this subject.
1. Fertilization: Union of a sperm and egg; occurs in a fallopian tube.
2. Fetus: Stage of a developing baby between the end of the 8th week after fertilization and birth.
3. Eggs: Female gametes or sex cells.
4. Embryo: Stage of a developing baby between implantation and the end of the 8th week after fertilization.
5. Epididymis: Male reproductive organ where sperm mature and are stored until they leave the body.
6. Estrogen: Main sex hormone in females.
7. Fallopian tubes: Female reproductive organs through which eggs pass to reach the uterus and where an egg may unite with a sperm.
8. Follicle: Nest of cells in an ovary that enclose an egg; protects egg during maturation prior to ovulation.
9. Implantation: Process in which the ball of cells that will become an embryo embeds in the lining of the uterus.
10. Menstruation: Monthly shedding of the lining of the uterus through the vagina; also called a menstrual period.
11. Penis: Male reproductive organ that carries urine and sperm out of the body.
12. Placenta: Spongy mass of blood vessels from the mother and fetus that allows substances to pass back and forth between the mother’s blood and the fetus’s blood.
13. Ovaries: Female reproductive organs that produce eggs and secrete estrogen.
14. Ovulation:Release of an egg by an ovary.
15. Semen: Milky liquid that contains sperm and secretions of glands; passes through the urethra and out of body.
16. Sperm: Male gametes or sex cells.
17. Testosterone:Main sex hormone in males.
18. Testes: Male reproductive organs that produce sperm and secrete testosterone.
19. Uterus: Female reproductive organ where a baby develops until birth.
20. Vagina: Female reproductive organ where sperm are deposited and through which a baby passes to leave the mother’s body during birth.
21. Umbilical cord: Tube containing blood vessels that connects a fetus to the placenta.
22. Zygote: Cell that forms when a sperm and egg unite; the first cell of a new organism.

The reproductive system

You are supposed to remember the most important about reproduction becouse you studied last year. In case you had forgotten, in this post we will begin with a review of the last year.

Reproduction is the biological process by wich new individual organism are produced. It ensures the perpetuation of the species.

There are two main types of reproduction:

Asexual reproduction requires only one parent which produces new, genetically identical living beings.
Sexual reproduction requires two parents: a male and a female. The descendants have a combination of genetic material contributed from both parents.

Sexual reproduction in animal usually requires two members of the opposite sex, a male and a female. Each member has different reproductive organs called gonads. These organs make reproductive cells called gametes.

The male gonads are the testicles and the male gametes are the spermatozoa.

The female gonads are the ovaries and the female gametes are the ova.

Fertilisation is the union of an ovum and a spermatozoon. They form a zygote.

There are two types of fertilisation:

External fertilisation when the union of the gametes occur s outside the female body. It is typical of the acuatic animal.

Internal fertilisation is the fusion of gametes which occurs inside the female body. It involves copulation, which is the transmision of spermatozoa of the male into the female reproductive system trough a copulating organ. It is typical the most of terrestrial animal.

Human living beings have this type of fertilisation . In next post we will find informatión about human reproduction.

martes, 17 de mayo de 2011

Skeleton vocabulary

I'm sure some of you were missing the post about the vocabulary:

  • Bone marrow Soft connective tissue found inside many bones; site of blood cell formation.

  • Cartilage Smooth covering found at the end of bones; made of tough collagen protein fibers; creates smooth surfaces for the easy movement of bones against each other.

  • Compact bone The dense, hard outer layer of a bone.

  • Joint Point at which two or more bones meet.

  • Ligaments Fibrous tissue that connects bones to other bones; made of tough collagen fibers.

  • Movable joint Most mobile type of joint; the most common type of joint in the body.

  • Skeletal system Body system that is made up of bones, cartilage, and ligaments.

  • Skeleton Sturdy scaffolding of bones and cartilage that is found inside vertebrates.

  • Spongy bone Lighter and less dense than compact bone; found toward the center of the bone.

  • Sprain A ligament injury; usually caused by the sudden overstretching of a joint which causes tearing.

martes, 10 de mayo de 2011

Joints and How they move

A joint is a point at which two or more bones meet. There are three types of joints in the body:
Fixed joints is a joint between two bones that doesnt move . Many of the joints in your skull are fixed joints. The skull plates don't move together or against each other, but they are connected or fused
Partly movable joints allow only a little movement..Your backbone has partly movable joints between the vertebrae. They are connected to each other by pads of cartilageand ligaments. They can only move a small amount
Movable joints allow movement and provide mechanical support for the body. Movable joints are the most common type of joint in your body. Your fingers, toes, hips, elbows, and knees all have movable joints. The surfaces of bones at movable joints are covered with a smooth layer of cartilage. The space between the bones in a movable joint is filled with a liquid called synovial fluid. The fluid lubricates and cushions the bones when they move at the joint. Ligaments help provide their stability and muscles contract to produce movement.
The knee joint is the largest joint in the body, consisting of 4 bones- the femur (thigh bone), the tibia (shin bone), fibula (outer shin bone) and patella (kneecap)- and an extensive network of ligaments and muscles..
There is a joint capsule that is a thick ligamentous structure that surrounds the entire knee. Inside this capsule is a specialized membrane known as the synovial membrane which provides nourishment to all the surrounding structures. The capsule itself is strengthened by the surrounding ligaments.
The stability of the knee owes greatly to the presence of its ligaments. Each has a particular function in helping to maintain optimal knee stability in a variety of different positions. There are two Collateral Ligaments ( inner and outer side) and two Cruciate ligaments.
Each knee joint has two crescent-shaped cartilage menisci. These lie on the medial (inner) and lateral (outer) edges of the upper surface of the tibia bone. They are essential components, acting as shock absorbers for the knee as well as allowing for correct weight distribution between the tibia and the femur.