Sections Endocrine System The function of the endocrine system is to produce chemical messengers (hormones) from glands to regulate certain body activities.
Roles of endocrine glands: Pituitary: controls other glands Pineal: regulates sleep and wake cycles, along with other basic functions Hypothalamus: controls secretions of the pituitary gland Thyroid: regulates metabolism Parathyroid: maintains homeostasis in blood calcium levels Adrenals: helps body prepare for and deal with stress Pancreas: releases insulin and glucagon to regulate level of glucose in blood Ovaries (female): produces eggs and estrogen to create female characteristics Testes (male): produces sperm and testosterone to create male characteristics
Sections 34.3 & 34.4 Reproductive System Structures of the male reproductive system: Testes: primary male reproductive organ; produces sperm and releases hormone testosterone Scrotum: sac that houses the testes; it can raise or lowers to adjust the temperature so that it is optimal for sperm development Epididymis: comma shaped structure found on outside of testes; sperm travel here from testes to mature
Vas deferens: tube leading to the epididymus to urethra; stores sperm until they are released from the body Seminal vesicles: first gland that sperm pass on their way out of the body; secretes a liquid containing fructose to nourish sperm and give them energy needed to swim Prostate gland: next gland; secretes an alkaline substance that makes up most of the seminal fluid; this fluid protects sperm from acid in male urethra and increases motility
Bulbourethral gland: last gland; small and closest to urethra; secretes an alkaline substance often secreted before ejaculation to prepare urethra for sperm Urethra: passageway leading from bladder to exterior of body; common outlet for semen and urine Penis: organ through which urine or semen must pass to exit the body; organ by which semen is introduced to female vagina
Glans penis: enlarged end of penis; the head Ejaculation: when male is sexually aroused, autonomic nervous system prepares male organs to deliver sperm; smooth muscles lining glands of reproductive tract contract and eject sperm from male body; If sperm are released into reproductive tract of female, chances of one sperm finding an egg are quite good
Structures of the female reproductive system: Ovaries: primary female reproductive organs; produce eggs and release estrogen Fimbrae: fingerlike projections that accept the egg from the ovary to to the Fallopian tube Fallopian tubes: tube that carries mature egg from ovary to uterus; place where fertilization ocurs
Uterus: hollow muscular cavity that receives the fertilized egg and where the fetus develops; where the egg disintegrates if not fertilized Cervix: lower portion of uterus; opening that leads to the vagina Vagina: passageway that leads from uterus to outside body; where babies pass through to be born and male’s penis is introduced
Vulva: collective term for the external reproductive organs of the female Clitoris: small organ made of erect tissue; homologous to the head of the penis Endometrium: the lining of uterus; each month it becomes thick to prepare for fertilization; sloughed off if no fertilizations Ovulation: process of releasing an egg from the ovary
4 Phases of Menstrual Cycle Follicular Ovulation Luteal Menstruation
Zygote’s Early Development Initially the zygote is a single cell just the size of a dot At four days, embryo is about 64 cells 6-7 days after fertilization, embryo implants into uterine wall Placenta forms by 3 rd week. It is the organ through which mother and child exchange gases and nutrients; the blood of the mother and infant do not actually mix, but flow past each other and gases and nutrients diffuse across thin membranes
The amniotic sac also develops, which is a fluid filled sac that protects the baby within the uterus. After 4 weeks, the heart starts beating After 6 weeks, limb buds appear
Later Stages of Development By 3 months, most of the baby’s major organs have formed. During 2 nd trimester, the mother starts to visibly look pregnant, the fetal heartbeat can be heard from a stethoscope, and mother can feel fetus move In the 3 rd Trimester, the organ systems mature and the fetus doubles in size.
Childbirth After 9 months, the child is fully developed and ready to be born. Oxytocin is released, which causes contractions of the uterine walls. Cervix opens Amniotic sac breaks The after-birth follows: the placenta, amniotic sac, and umbilical cord still attached