HUMAN MEDICAL BIOLOGY, ANATOMY, PHYSIOLOGY, AND PATHOLOGY - Ya.I. Fedonyuk 2010

ANATOMY, PHYSIOLOGY, PATHOLOGY

SECTION 3. ANATOMICAL AND PHYSIOLOGICAL ASPECTS OF BODY FUNCTION SELF-REGULATION

ENDOCRINE GLANDS AND THEIR PATHOLOGY

GONADS

The Gonads (see the chapters "Testes" and "Ovary") consist of two components: exocrine and endocrine. The Endocrine Component of the Testis is represented by interstitial Cells (Leydig cells) located between the convoluted seminiferous tubules. The endocrine component of the ovary is found within the maturing follicle and the ovarian interstitial cells.

The gonads are classified as mixed glands possessing both secretory and incretory Functions. The secretory function involves the production and release of Male Germ Cells (spermatozoa) and Female Germ Cells (ova). The incretory function is associated with the synthesis and release of Sex Hormones into the bloodstream. Sex hormones are divided into male and female types. Both types are produced in both females and males, albeit in different concentrations: males produce predominantly Male Sex Hormones with low concentrations of female hormones, whereas females show the reverse pattern.

Male sex hormones include androgens (with testosterone as the primary representative). Female Sex Hormones comprise estrogens (estradiol, estrone) and progestins (progesterone).

The male gonads begin synthesizing androgens as early as the 3rd month of embryonic development, which directs The formation of the Male reproductive Organs. After a boy's birth, androgen synthesis ceases and resumes only during Puberty (ages 12-16).

In girls, the incretory function of the gonads begins exclusively during puberty. Under METABOLISM/18.html">The Influence of estrogens in girls and androgens in boys, the reproductive organs grow and mature, leading to The Development of primary sex characteristics. Furthermore, these hormones promote the appearance of secondary sex characteristics—the distinctive features of a mature Organism that differentiate men from women (body shape, Hair distribution, voice pitch, psychological traits, and behavior).

Androgens are essential for the normal development and motility of spermatozoa. They regulate specific emotional states and influence psychological well-being. The well-known anabolic effect of these hormones involves the activation of Protein Synthesis, which drives the intensive growth of Muscles and organs and increases body mass.

Under the influence of androgens, the erythrocyte count in the Blood increases, basal metabolism rises, and lipid content in organs decreases.

Estrogens also influence a woman's psychological and emotional state and shape her Sexual Behavior. In addition, their action periodically triggers menstruation. These hormones promote the contraction of the uterine muscles.

Progesterone is the hormone of Pregnancy; it is produced in the corpus luteum and regulates processes associated with the initiation and normal progression of pregnancy. It induces proliferation of the endometrium, facilitating the implantation of the fertilized egg in the Uterus. By acting on the smooth Muscle of the uterine wall, progesterone inhibits contractions and reduces sensitivity to oxytocin. Progesterone also promotes mammary gland growth during pregnancy and prevents the maturation and ovulation of follicles, thereby blocking the release of ova.

The regulation of sex hormone production is mediated by the hypothalamo-pituitary system via gonadotropic hormones: follicle-stimulating hormone and luteinizing hormone.