Adult Nutrition Notes

Topics: Obesity, Puberty, Nutrition Pages: 16 (3078 words) Published: August 25, 2013
Adolescence

Introduction
* Many levels of change occurring
* Individual = undergoes change biologically cognitively and psychologically * Social =
* Three phases
* Early = ages 11-14; defined by changes of puberty and response to those changes * Middle = ages 15-17; defined by stereotypical time of peer-dominated changes * Late = ages 18-20; defined by more adult like behavior and adaptation to adult lifestyle

Anatomy/Physiological Maturation
* Physical changes occur during early adolescence
* The first major change is puberty = a predictable sequence of hormonal and physical changes that occur over a defined period of time encompassing both physical growth and sexual maturation

* Initiation of puberty
* Leptin- we used to think it was all controlled by this * As body fatness increases, so does blood concentration of leptin * Neurons in the hypothalamus of the brain mature becoming more sensitive to leptin * Mature neurons produce Gonadotropin

* Now we think Leptin is a “Permissive factor”

* Acts on the anterior pituitary to make and release Follicle-stimulating hormone and Luteinizing hormone LH into the blood * These two hormones, among other things, stimulates sexual maturation * Occurs in both genders

* Girls:
* FSH stimulates growth of ovarian follicles and production of estrogen * LH initiates ovulation with the formation of the corpus luteum and progesterone production

* Boys:
* FSH acts directly on the leydig cells in the testicles to promote testicular maturation * Both FSH and LH are required fro testosterone production and spermatogenesis

* Actions of reproductive hormones
* Girls
* FSH: stimulates estrogen production
* Estrogen concentration gradually increases allowing for thickening of the endometrial lining * NOTE: estrogen decreases FSH
* One adequate estrogen levels have been achieved, the endometrial lining will shed * Menarche= first menses
* NOTE: usually no associated ovulation

* Progesterone: levels must also increase with estrogen to promote development and release of one ovarian follicle= true ovulation

* True ovulation may take up to one year after menarche * Following ovulation: progesterone and estrogen levels fall * This causes FSH to increase= negative feedback loop * The cycle repeats itself

* The fluctuations of these hormones cause ___________________________ * Boys
* FSH and LH: lead to increase production and secretion of testosterone * Equivalent to female menarche? - No
* Viable sperm produced about one year after initial hormone surge and the beginning of testicular maturation

* Increases in testosterone causes growth of skeletal muscle and accretion of bone mass

* Testosterone work s to decrease FSH and LH stimulation = negative feedback loop * Unlike the feedback loop in girls = no fluctuation in hormones (no cycling) * Both genders

* Estrogen:
* Development of secondary sexual characteristics (breast development, hip widening and pubic and axillary hair) * Stimulates bone growth when at low levels
* High levels of estrogen inhibits bone growth especially in the long bones (femur tibia, humerus, ect)

* Testosterone and other androgens:
* Development of acne and body odor

* These actions occur in a predictable pattern = tanner staging or sexual maturation rating (SMR) * Describes: stages of pubertal growth with respect to physical...
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