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BIO Unit 4 Review
Explain how hormones work in your body, including the roles of endocrine cells, circulatory system, target cells, and receptors
Hormones role is to relay messages to the organs and glands
endocrine cells are responsible for chemical signaling to the organs and glands
the circulatory system transports hormones to target tissues throughout the body
target cells have specific receptors that bind to the hormone
receptors are where the target cells land
Describe how the structure of different hormones affectstheir function and receptor location (i.e. the differencebetween protein-based vs lipid-based hormones).
Protein-based hormone bind to receptros are on the surface.
water-soluble, cannot cross cell membranes
steriod base hormones deals with gene expression and protein production
steriod base hormones receptors are inside
Give examples of target cell responses that are initiated by hormones binding to their receptor.
Protein-based hormone example:
Insulin binds to surface receptors → increases glucose uptake in muscle cells via GLUT4 transporters.
Lipid-based hormone example:
Cortisol binds to intracellular receptors → activates genes for gluconeogenesis in liver cells.
Understand how hormones are regulated (i.e. positive andnegative feedback) and that this is how your bodymaintains homeostasis (“set point”).
Negative feedback: Maintains balance by reducing hormone activity when the desired effect is achieved.
Example: High blood glucose → insulin secretion → glucose uptake → blood glucose drops → insulin secretion decreases.
Positive feedback: Amplifies a response until a specific outcome is achieved.
Example: Oxytocin during childbirth → uterine contractions → more oxytocin release → stronger contractions.
Given information on stimuli and responses, be able todetermine whether a system is regulated by either positive ornegative feedback.
Negative feedback: If the system returns to a "set point" after the response.
Example: Thyroid hormones regulate metabolism by inhibiting TSH and TRH secretion when levels are sufficient.
Positive feedback: If the response amplifies until an external event ends it.
Example: Blood clotting cascade amplifies clot formation until the wound is sealed.
Practice using the language of biology to describe malereproduction (testes, epididymis, vas deferens, penis,spermatogenesis, etc.)
Testes: Paired organs located in the scrotum, responsible for producing sperm (spermatogenesis) and testosterone.
Epididymis: Coiled tube on the back of each testis where sperm mature and are stored.
Vas deferens: Muscular tube that transports sperm from the epididymis to the urethra during ejaculation.
Penis: Organ used for the delivery of sperm to the female reproductive tract and for urination.
Accessory glands (e.g., seminal vesicles, prostate gland, bulbourethral glands): Produce fluids that nourish sperm and form semen.
Explain the key ideas about spermatogenesis (howit happens, where it happens, how long it takes, etc.)
Definition: The process of sperm production.
Location: Occurs in the seminiferous tubules of the testes.
Steps:
Spermatogonia (stem cells): Divide by mitosis to maintain the germ cell population.
Primary spermatocytes: Form through mitotic division and enter meiosis I.
Secondary spermatocytes: Result from meiosis I and undergo meiosis II to form spermatids.
Spermatids: Differentiate into mature spermatozoa (sperm) through a process called spermiogenesis.
Support cells:
Sertoli cells: Provide nutrients, remove waste, and create the blood-testis barrier.
Leydig cells: Produce testosterone, which is critical for spermatogenesis.
Timeline: Takes approximately 64-72 days for a complete cycle.
Describe how hormones control the process ofspermatogenesis (GnRH, LH, FSH, testosterone, inhibin)13Dr. Morgan Meyers | BIOL1104 | Thurs.
GnRH (Gonadotropin-releasing hormone):
Secreted by the hypothalamus.
Stimulates the anterior pituitary to release LH and FSH.
LH (Luteinizing hormone):
Targets Leydig cells in the testes.
Promotes testosterone production, which is essential for spermatogenesis.
FSH (Follicle-stimulating hormone):
Acts on Sertoli cells to stimulate spermatogenesis and the production of androgen-binding protein (ABP), which helps maintain high local testosterone levels.
Testosterone:
Produced by Leydig cells.
Promotes spermatogenesis, secondary sexual characteristics, and libido.
Exerts negative feedback on GnRH and LH secretion.
Inhibin:
Secreted by Sertoli cells in response to FSH stimulation.
Provides negative feedback to the anterior pituitary to regulate FSH levels.
Practice using the language of biology (ovaries, follicle, corpus luteum,ovulation, oogenesis, uterus, menstruation, menstrual cycle, endometrium)
Ovaries: They produce eggs (ova) and hormones such as estrogen and progesterone.
Follicle: Follicles mature during the menstrual cycle, releasing an egg during ovulation.
Corpus Luteum: secretes progesterone and some estrogen to maintain the uterine lining for potential implantation.
Ovulation: The process by which a mature follicle ruptures to release an egg (secondary oocyte) from the ovary into the fallopian tube.
Oogenesis: The process of egg (ovum) formation in the ovaries, which begins before birth and continues through puberty and the reproductive years. It involves the maturation of primary oocytes into fertilizable eggs.
Uterus: A hollow, muscular organ in the female pelvis. It houses and nourishes a fertilized egg during pregnancy. If no pregnancy occurs, its lining is shed during menstruation.
Menstruation: The monthly shedding of the uterine lining (endometrium) in the absence of pregnancy. It results in bleeding through the vagina and typically lasts 3-7 days.
Menstrual Cycle: A recurring series of physiological changes in the female reproductive system, typically lasting 28 days, which prepares the body for pregnancy. It includes the ovarian cycle (follicular phase, ovulation, luteal phase) and the uterine cycle.
Endometrium: The inner lining of the uterus, which thickens during the menstrual cycle in preparation for a fertilized egg. If implantation does not occur, it is shed during menstruation.
Describe the process of oogenesis and how it relates todisorders like polycystic ovarian syndrome.
Oogenesis is the process by which female gametes (ova or eggs) are formed within the ovaries. It begins before birth, when germ cells in the ovaries undergo mitosis to form primary oocytes, which then enter meiosis I but remain arrested in prophase I until puberty.
During each menstrual cycle, a few primary oocytes resume meiosis I under hormonal stimulation, resulting in a secondary oocyte and a polar body. The secondary oocyte progresses to metaphase II but completes meiosis II only if fertilization occurs. The process of oogenesis ensures that a mature egg is available for fertilization each cycle.
In conditions like polycystic ovarian syndrome (PCOS), oogenesis is disrupted. PCOS is characterized by the development of multiple ovarian follicles that fail to mature and ovulate, leading to anovulation (lack of ovulation). This is often due to hormonal imbalances, including excessive levels of androgens and insulin resistance, which interfere with normal ovarian function.
Describe the purpose and events of the ovarian cycle, andhow it is regulated by hormones.
The ovarian cycle encompasses the changes in the ovary during a menstrual cycle and consists of three main phases:
Follicular Phase (Days 1-14):
A follicle, containing a primary oocyte, matures under the influence of follicle-stimulating hormone (FSH).
The growing follicle secretes estrogen, which helps prepare the endometrium for potential implantation.
Ovulation (Day 14):
Triggered by a surge in luteinizing hormone (LH), the mature follicle releases the secondary oocyte into the fallopian tube.
Luteal Phase (Days 15-28):
The ruptured follicle transforms into the corpus luteum, which secretes progesterone and some estrogen.
If fertilization does not occur, the corpus luteum degenerates, leading to a drop in progesterone and estrogen, which initiates menstruation.
Hormonal feedback between the hypothalamus, pituitary gland, and ovaries regulates the ovarian cycle.
Describe the purpose and events of the uterine cycle, andhow it is regulated by hormones.
The uterine cycle describes changes in the endometrium of the uterus during a menstrual cycle to prepare for potential embryo implantation. It consists of three phases:
Menstrual Phase (Days 1-5):
Shedding of the functional layer of the endometrium occurs due to a decline in progesterone and estrogen levels.
Proliferative Phase (Days 6-14):
Under the influence of estrogen from the growing follicle, the endometrium regenerates and thickens.
Secretory Phase (Days 15-28):
Progesterone from the corpus luteum stimulates the endometrium to secrete nutrients, making it receptive for embryo implantation.
If fertilization does not occur, hormonal levels drop, leading to the onset of menstruation.
The uterine cycle is tightly regulated by estrogen and progesterone from the ovaries.
Describe the term "period poverty" and why it is an issue ofconcern.
Period poverty refers to the lack of access to menstrual hygiene products, education, or proper sanitation facilities due to financial constraints or societal stigma. It affects millions of menstruating individuals worldwide, particularly in low-income communities.
Why It’s a Concern:
Health Impacts: Lack of hygiene products can lead to infections and other health complications.
Education & Employment: Many individuals miss school or work due to inadequate menstrual care.
Stigma: Cultural taboos and misinformation perpetuate shame and prevent open conversations about menstruation.
