Reproduction Flashcards
Fever / pyrexia
Fever is condition in which body temperature arises above normal range.
1) Bacterial infections like typhoid
2) Tumors of brain - hypothalamus
3); Exposure to high environmental temperature - heat stroke.
Mechanism -
Toxins released by bacteria contain lipopolysaccharides called exogenous pyrogenes.
These act on macrophages, monocytes and kupffers cells and cause release of interleukin 1 or endogenous pyrogenes.
Interleukin 1 causes formation of prostaglandin which act on neurons of preoptic area and reset hypothalamic thermostats at higher level like 40⁰.
Hypothalamus interprets that existing body temperature is less than reset value and causes cutaneous vasoconstriction and shivering.
Advantage is rise in body temperature helps to kill bacteria. It accelerates process of antibody formation.
Applied aspect- antipyretics like aspirin suppress prostaglandin synthesis & prevent pyrogenic effect of interleukin.
Functions of placenta
1) Respiratory function -
O2 diffuse from maternal blood to fetal blood through placenta and vice versa for CO2. Fetal Hb has more affinity for O2 than adult human and has more Hb.
2) Nutritive function - Nutrients for fetal growth are transported through placenta by simple diffusion, facilitated diffusion or active transport like glucose, amino acids and fatty acids and minerals and electrolytes.
3) Excretory function - Fetus excretes waste products from fetal to maternal blood through placenta like urea, uric acid and creatinine by diffusion.
4) Endocrine function -
A) HCG - Maintain corpus luteum during pregnancy.
B) Oestrogens and progesterone - maintain decidual changes in endometrium and prepares breast for lactation.
C) HC somatotropin which promotes growth of Fetus in mother.
D) Thryotropin - stimulate thyroid gland during pregnancy.
E) Relaxin - relaxes pelvic ligaments of uterus.
5) Storage function - placenta stores fats and glycogen.
6) Protective function - Transports immunoglobins to Fetus and gives passive immunity.
Test to detect pregnancy
Galravindex test is used to detect pregnancy.
Principle is based on detection of HCG in urine of suspected women by immunological methods.
Menopause
Physiological condition characterized by ceasation of ovarian and menstrual cycles in woman.
Cause is non responsiveness of ovary towards pituitary gonadotropins , LH and FSH. So no formation of graffian follicle and no ovulation.Secretion of estrogen and progesterone by granulosa cells also falls down.
Changes taking place at menopause-
1) Atrophy of ovary, uterus and fallopian tube
2) Vagina becomes atrophic and thin walled.
3) Atrophy of breasts.
4) Increase in blood levels of FSH and LH due to loss of negative feedback inhibition by sex hormones.
5) psychological conditions like disturbance and anxiety are seen.
6) osteoporetic changes and fractures may occur due to lack of estrogens which are involved in bone matrix formation.
7) Pain in joints and arthritis.
Process of spermatogenesis
The process of formation of spermatozoa from primitive germs cells is called spermatogenesis.
Stages of development are spermatogenia undergo mitosis to form primary spermatocyte which undergoes first meiotic division to form secondary spermatocyte which undergoes second meiotic division to form sermatid which undergoes maturation to form spermatozoa.
Function of sertoli cells:
1) Maturation of spermatid to spermatozoa
2) Provide nutrition to sperms
3) Secrete mullerin inhibition factor
4) Form blood testis barrier
Factors affecting spermatogenesis:
1) Hormones
• LH secreted by Pituitary acts on leydigs cells to secrete testosterone which stimulates spermatogenesis.
• FSH secreted by anterior pituitary acts on sertoli cells and promotes Maturation of spermatid. It secreted inhibin which has negative feedback effect on FSH.
• Oestrogens acts on sertoli cells and promotes spermatogenesis.
• Growth hormones also essential for spermatogenesis.
2) Temperature
• 2⁰-5⁰ less temperature than body temperature.
• maintained by sweat glands of scrotum, dartos muscle and vascular layer.
Actions and regulation of testosterone
Testosterone is secreted by Leydigs cells when they get stimulated by LH which is released from anterior pituitary.
In fetal life
1) Sex differentiation
2) Descent of Testis
At time of puberty
1) Growth of external gentilia and accessory sex organs
2) Development of secondary sexual characteristics like:
• Growth of beard and moustaches
• Developement of low pitch hoarse shaped voice
• male emotional pattern like aggressiveness
• Skeletal growth and fusion of epiphysis with shaft of bone.
In Adult Life
• Stimulates spermatogenesis
• Protein anabolic action
• Increases BMR
• Thick skin and acne formation
• Production of erythropoietin
Regulation
• LH stimulates secretion
• LHrH stimulates secretion
• High BP have negative feedback on secretion.
• Prolactin stimulates action
Menstrual cycle
Menstrual cycle is 28 days cycle.
3 phases which are Proliferative, Secretory and Menstrual phase.
Proliferative phase
5-14th day
In this phase there is increased secretion of FSH and LH levels. Increased FSH levels causes growth and Maturation of ovarian follicle. This follicle starts secreting Oestrogens and it’s level increases which causes
• Proliferation of endometrial glands.
• stromal cells, blood vessels and growth of epithelial tissue.
• Increase in endometrial thickness.
On 12th day, high estrogen level causes LH and FSH surge causing ovulation. LH surge is also responsible for formation of corpus luteum.
Secretory Phase
15-28th phase
In this phase , initially LH level is high but corpus luteum starts secreting large levels of oestrogen and progesterone which further causes growth of endometrial tissue and increase its thickness and also causes negative feedback inhibition of LH and FSH.
LH is necessary for maintaining of corpus luteum. Low LH levels degenerates corpus luteum which in turn results in decrease in levels of Oestrogens and progesterone.
Menstrual Phase
1-4th day
It occurs due to sudden withdrawal of oestrogen and progesterone. Lack of hormonal support as well as constriction of spiral arteries causes necrosis of endometrial tissue. There is release of few ml of blood with unfertilized ovum along with superficial 2/3rd of endometrium.
Describe the action of female sex hormones.
There are Oestrogens and progesterone.
Oestrogen
Secreted by granulosa cells in ovary, placenta and sertoli cells in males.
• At time of puberty and during pregnancy it causes enlargement of uterus and proliferation of endometrial glands, stromal cells and blood vessels.
• Causes increase in size of vagina and stratification of vaginal epithelium.
• It causes ext. gen. enlargement like labia majora and minora and deposition of fat in mons pubis.
• Causes increase in size of fallopian tube and growth of ciliated epithelium.
• Acts on breast and cause growth of stromal tissue and development of duct system.
• Increased BMR
• Fat deposition in subcutaneous tissue.
• Acts on skeletal system and causes fusion of epiphysis with shaft.
• Skin becomes smooth, soft and vascular.
Progesterone
Secreted by placenta and corpus luteum.
• Acts on uterus during pregnancy causing it’s enlargement
• Acts on mucosa of fallopian tubes and causes secretory changes.
• Acts on breast to enlarge breast and cause secretory nature.
• Increases BMR and body temperature
• High progesterone levels suppresses LH secretion.
Enumerate hormones secreted by placenta
1) Human chorionic gonadotropin
2) Progesterone
3) Oestrogen
4) Human chorionic somatotropin
5) Human chorionic thyrotropin
6) Relaxin
