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Physiological changes includes changes in
- Metabolic rate
- Blood pressure
- Respiratory rate
- Activation of oil producing glands in skin
Another important change is functioning of endocrine glands. The endocrine system, which circulates and regulates hormones within the body, develops before birth but stays relatively inactive until the age of 7. At that time the system gradually begins to secrete hormones into blood stream during sleep.
These hormones called gonadotrophins. They travel to the brain carrying messages about changes to the body. Boys and girls approximately have the same amounts of these sex hormones in their bodies throughout most of the childhood, but during early adolescence this balance changes. In girls the key hormone is Estrogen, in boys Androgen and Testosterone. The relative amounts of these hormones in the body account for the physical changes associated with puberty. Ex: hair growth is related to androgen.
The hypothalamus in the brain signals the secretion in pituitary gland, which in turn stimulates thyroid, adrenal glands (testis and ovaries). Though both sexes secrete male and female hormones, male hormones (testosterone) greatly increase in boys and female hormones (estrogen) in girls which causes differentiation in physique.
The anterior pituitary produces growth hormone to increase in height and weight, enlarges bones of the skeleton, increases muscle mass, enlarges individual organs like heart and helps to build up protein in the human tissue cells. About 2 years after menarche, height gain completes and attains adult height. The main hormones produced by pituitary glands are FSH (Follicle Stimulating Hormone) and LH (Luteinising hormones) in the girls and ICSH (Interstitial Cell Stimulating Hormone) in boys. They stimulate the production of sex hormones like Estrogen and Progesterone in females and Testosterone in males.
Another hormone from the anterior pituitary called ACTH (Adrenal Corticotrophic Hormone) causes the adrenal glands (above the kidneys) to increase the production of androgens in the both sexes.
follicle stimulating hormone
Androgens from the adrenals in maturing boys and girls are responsible for the appearance and growth of hair under arms, axillary hair, pubic hair, hair around the genital area. It will begins about 11 years of age and not fully complete by seventeenth year.
The effects of testosterone and androgen in the pubertic boy:
The effects of testosterone and androgen in the pubertic boy are
- Voice deepens as the larynx grows, changes from high pitch to a lower pitch
- The pennies enlarges, the scrotal skin thickens (change in texture and colour), inside the testis the pair of oval shaped gonads or sex glands starts manufacturing the sperm by the formation of seminal fluid.
- The skin becomes more oily and greasy. This stems from sebum production by the enlarged sebaceous glands . the too much sebum associated with a skin complaint is known as acne. This is more common in adolescent boys than girls.
The Osterogen is responsible for the youthful skin of adolescence and subsequent adulthood. The thymus gland starts to wither away and thyroid gland in the neck may enlarge.
Effects of Osterogen on the pubertic girl :
Effects of osterogen on the pubertic girl are
- In the genital area, the pubic mound enlarges beneath the growing pubic hair and the lips of vulva or labia majora become much larger.
- The vagina becomes larger and the uterus also grows in size and structure.
- The body portion of the uterus starts functioning, the menstrual cycle called menarche. This generally appears in the 13 years (11-16 years). An adolescent not yet menstruated after 16 years should be referred for medical advice. Menstruation is often irregular in the beginning of monthly cycles and no ova is actually be discharged in the early periods. Once the ovaries start producing ovum on a regular basis then the adolescent is physically mature for human reproduction.
Change in Blood pressure: A spurt in the blood pressure takes place at puberty to accommodate the changes in size and function of other organs. The blood pressure as measured in the upper arm is an indication of the force of the output of the human heart and of the resistance in the elastic arteries which carry the blood away from the heart. By the age of 15 years the adolescent blood pressure has reached normal adult level.
Other subtle changes – includes the following
- Heart grows rapidly
- Length and thickness of walls of blood vessels increase
- Lung capacity reaches to its mature level
- Intestines grow in length
- Muscles of stomach and intestinal wall become thicker and stronger
- Body tissues other than bones continue to develop, after the bones have reached their mature size.
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