Unit 15 ~ Learning Guide Name: INSTRUCTIONS Complete the following notes and questions as you work through the related lessons. You are required to have this package completed BEFORE you write your unit test. Do your best and ask questions about anything that you don't understand BEFORE you write the unit test. U15 NOTES: REPRODUCTIVE SYSTEMS (web notes) Male Reproductive System Testes (male gonads) Produce Produce Found in a sac called the Suspended outside of the body cavity for Testes wall made of fibrous connective tissue (divides the testes into lobules/chambers) inside chambers are long tubes (70cm) called the This is the actual site for. Interstitial cells secretes androgens " " Spermatogenesis: Sperm Development Sperms cells are derived from undifferentiated cells called SPERMATOGONIA (sing. Spermatogonium), which lie just on the outside wall of a tubule and divide mitotically, always producing new spermatogonia. Some newly formed spermatogonia move away Page 1 of 28
from the outer wall to increase in size and become primary spermatocytes, which undergo meiosis, a type of cell division. Primary spermatocytes, with 46 chromosomes, divide to give 2 secondary spermatocytes, each with 23 chromosomes. Secondary spermatocytes divide to produce 4 spermatids, also with 23 chromosomes, but each only having one chromatid. Spermatids then differentiate into sperm (spermatozoa). Also present in the tubules are the SERTOLI cells, which support, nourish and regulate the spermatogenic cells. Male Reproductive Structures Epididymis. Seminal Vesicle. Cowper's Gland Pea-sized organs that lie posterior to the prostate on either side of the urethra.. Prostate Gland A single dough-nut shaped gland that surrounds the upper portion of the urethra just below the bladder. Older men can have their prostate become enlarged and urination becomes quite painful (surgically fixed). Urethra. Ductus Vas Deferens. Page 2 of 28
Penis. Sperm Structure/Function 1. Formed in the seminiferous tubules of the testes 2. Mature and stored in the epididymis 3. Stored in the Vas Deferens 4. Enters the urethra just prior to ejaculation 5. Accessory glands (prostate, Cowper's gland, and seminal vesicle) add secretions to semen. 6. Semen and sperm exit through the penis SOURCES: 1. Seminal Vesicle 2. Prostate Gland 3. Cowper's Gland FUNCTION: 1. Produce basic fluid, ph 7.5 (slightly basic) is ideal for healthy sperm and thus, a basic fluid is needed to. 2. Provides for sperm. 3. Contains - chemicals which cause the uterus to contacts. 4. Aids in the to the egg (mucous) 5. Parts of the Sperm 1. Head: contains 23 chromosomes attached = type of. contains. digests the so sperm can penetrate. 2. Middle Piece: Contains mitochondria - 3. Tail: Page 3 of 28
Function of Testosterone 1. Essential for development of 2. Essential for the development of. spermatogenic cells take up which stimulate their activity. 3. Increase testosterone concentration at puberty causes 4. Secondary sex Characteristics facial hair pubic hair oil and sweat gland secrete(=stinky) larynx expands (voice changes) increase muscular strength sex drive NOTE: Side effect is baldness if genetically predisposed Page 4 of 28
Hormonal Control of Testosterone Hypothalamus releases GnRH ( ) GnRH causes anterior pituitary to release 2 gonadotropic hormones: 1. FSH ( ) promotes spermatogenesis in the seminiferous tubules 2. LH ( ) promotes production of testosterone in interstitial cells NEGATIVE FEEDBACK Increase testosterone concentration in the blood causes the to make and therefore, testosterone is produced. Decrease testosterone concentration in the blood causes the to make more LH and therefore, more testosterone is. Increase concentration of stored sperm causes an increase in production of and decreases production of FSH, therefore production of sperm. Decrease concentration of stored sperm causes a and more FSH, therefore is produced Page 5 of 28
Female Reproductive Structures Cervix Narrow end of uterus leading to the vagina. dilates to allow baby to exit. Clitoris female sensory organ; homologous to the male penis. provides sensitivity during intercourse. Labia major and Labia minor protective folds of skin. Vestibule cleft between the labia minor. contains opening (orifices) to the urethra and vagina. Fimbriae Finger-like projections of the. along with cilia in the oviducts, they cause a which sweeps the egg. Oviduct conducts towards the also called the or uterine tube. Ovaries produce. Uterus (Womb). Vagina Receives penis during sexual intercourse and serves as a. Page 6 of 28
Functions of Estrogen 1. Stimulates growth of. 2. Egg maturation 3. Secondary Sex Characteristics: armpit hair/pubic hair enlarged (wider hips) breast development (requires as well) Ovarian Cycles Day 1-13 Follicular Phase 1. Hypothalamus produced a GnRH to stimulate. 2. FSH and LH from pituitary gland stimulates. 3. Primary follicle (46 chromosomes) contains primary which divides. (produced ) One oocyte get most (called a secondary oocyte, which is inside the now secondary follicle). 4. Other oocyte called the disintegrates. 5. The secondary follicle grows into a (vesicular) Follicle. Page 7 of 28
Day 14 Ovulation 6. Grafian Follicle (ovulation) LH is at its highest and triggers ovulation. Day 17-28 Luteal Phase 7. The follicle has lost its oocyte (or "egg") and forms into the corpus luteum If pregnancy does not occur: breaks down (about 10 days) If pregnancy does occur: Corpus Luteum remains for 3-6 months and continues to produce. Cycle will repeat. Uterine Cycle Day 1-5 Menstruation 1. Low levels of sex hormones ( has just disintegrated). 2. (lining of Uterus) breaks down. 3. Cells of the endometrium, blood vessels, and blood are and exit the vagina. 4. A flow of blood ( ) passes out of the vagina during a period called menstruation. Day 6-10 Proliferative Phase 5. Increase by the ovarian follicle causes the to rebuild. Page 8 of 28
Day 14 6. (release of egg). Day 15-28 Secretory Phase 7. Increase level of progesterone by the. 8. Endometrium doubles in thickness and becomes highly vascularized. 9. Glands produce. 10. Now prepared to receive embryo. If no pregnancy. The corpus luteum degenerates, decrease in progesterone production occurs and the endometrium breaks down. Cycles continues. Page 9 of 28
Hormonal Control FSH Hypothalamus secretes GnRH ( ) and causes the anterior pituitary to secrete. (days 1-13) (days 14-28) FSH causes Maturing follicles produce Increase in estrogen concentration causes the. Start of Day 1 13 Increase FSH Decrease FSH LH LH is released Large spike - day 14 ovulation (15-28) Causes the Corpus luteum Increase in progesterone cause anterior pituitary gland to stop producing LH. Day 15 - LH increases and progesterone. Day 28 - LH decreases and progesterone. YOU SHOULD CLICK ON THE LINK TO REVIEW THE FEMALE REPRODUCTIVE SYSTEM BEFORE YOU PROCEED ANY FURTHER. Page 10 of 28
Oxytocin and Positive Feedback Oxytocin. Contact of the fetal head with the cervix stimulates the release of oxytocin. Oxytocin causes the uterus to contract and contraction of the uterus causes the release of more oxytocin. Oxytocin also causes. Lobules containing milk contract forming milk into ducts which lead to the nipple. Implantation Implantation occurs in the. Fertilization occurs in the. Embryo embeds itself in the several days after fertilization. Membrane surrounding the embryo produced a hormone called HCG ( ). The Placenta then develops. It is found immediately in blood and a few days later in the urine. o HCG is the hormone detected by (about one week following implantation) HCG prevents the breakdown of the. The Corpus Luteum produced progesterone that keeps the from breaking down. FSH and LH production is inhibited which. Page 11 of 28
Placenta Contains both and is the area where. There is no exchange of. Diffusion of gases and wastes and nutrients occur across the. Placenta produces which maintains the corpus luteum. The corpus luteum continues to produce, which prevents breakdown of the, and estrogen which keeps new eggs from developing. YOU SHOULD CLICK ON THE LINK TO REVIEW AND COMPLETE THE REPRODUCTIVE SYSTEM PROBLEM SET BEFORE YOU PROCEED ANY FURTHER. Page 12 of 28
U15 PRACTICE: REPRODUCTIVE SYSTEMS 1. Label the following diagram of the male reproductive system. Provide a brief description of each structure's function below the diagram. Please be neat. (20 marks) 2. Why does sterility result if the testes do not descend into the scrotum? (2 marks) 3. What is spermatogenesis and where does it occur? (2 marks) Page 13 of 28
4. Where are the interstitial cells located? What is the function of these cells? (2 marks) 5. Identify the parts of a mature sperm and state the function of each part. (8 marks) 6. Explain how the hypothalamus and anterior pituitary gland function together to regulate sperm and testosterone production. Please explain the entire feedback loop using your own words/phrasing. (7 marks) Page 14 of 28
7. Label the following diagram of the female reproductive system. Provide a brief description of each structure's function below the diagram. Please be neat. (10 marks) Page 15 of 28
8. Give two ways that the oviduct aids the passage of the egg towards the uterus. (2 marks) 9. List five different effects of estrogen on the female body. (5 marks) Page 16 of 28
10. Complete the following table in relation to the female reproductive cycle. (13 marks) Hormone Full Name Source Effects GnRH FSH LH Estrogen Estrogen Progesterone Progesterone 11. The Ovarian Cycle: a. Identify the name given to Days 1-13 of the ovarian cycle and describe the changes in hormones and ovarian structures that occurs during this time. (3 marks) Page 17 of 28
b. Identify the name of the event that occurs on Day 14 of the ovarian cycle and specifically identify how hormone levels are responsible for influencing its occurrence. (2 marks) c. Identify the name given to Days 15-28 of the ovarian cycle and describe the changes in hormones and ovarian structures that occurs during this time. (3 marks) 12. The Uterine Cycle: a. Identify the name given to Days 1-5 of the uterine cycle and describe the changes in hormones and uterine structure that occurs during this time. (3 marks) Page 18 of 28
b. Identify the name given to Days 6-13 of the uterine cycle and describe the changes in hormones and uterine structure that occurs during this time. (3 marks) c. Identify the name given to Days 15-28 of the uterine cycle and describe the changes in hormones and uterine structure that occurs during this time. (3 marks) 13. Pregnancy and birth: a. Define implantation. (1 mark) b. What hormone is released from the membrane surrounding the embryo to prevent corpus luteum from degenerating? (1 mark) Page 19 of 28
c. Why is it important to prevent the corpus luteum from degenerating following implantation? (1 mark) d. What tissues does the placenta originate from? What are the hormonal and physical functions of the placenta? (3 marks) e. Why do the levels of estrogen and progesterone remain high during pregnancy and why is this important? (2 marks) Page 20 of 28
f. What are the functions of the hormone oxytocin and where does in originate? Describe positive feedback as it relates to this hormone. (4 marks) ~ END OF BIOLOGY 12 UNIT 15 LEARNING GUIDE ~ Page 21 of 28
UNIT 15 ANSWER KEY U15 PRACTICE: REPRODUCTIVE SYSTEMS 1. Label the following diagram of the male reproductive system. Provide a brief description of each structure's function below the diagram. Please be neat. (20 marks) Testes = produce sperm and testosterone Scrotum = hold testes away from body at a slightly lower temperature than body temperature as this is ideal for healthy sperm production Epididymis = stores sperm as they mature Seminal vesicle = contributes to seminal fluid Cowper's gland/bulbourethral gland = contributes to seminal fluid Prostate gland = contributes to seminal fluid Urethra = conduct sperm (and urine) out of the body) Vas deferens = carries sperm form testes to urethra Penis = organ of copulation Urinary bladder = stores urine Erectile tissue/corpora Cavenosa = fills with blood to create an erection Page 22 of 28
2. Why does sterility result if the testes do not descend into the scrotum? (2 marks) If testes remain within body they are held at a temperature that is too high to produce healthy sperm. 3. What is spermatogenesis and where does it occur? (2 marks) = production/development of sperm and it occurs in the testes 4. Where are the interstitial cells located? What is the function of these cells? (2 marks) = also known as Leydig cells, they are adjacent to the seminiferous tubules within the testes where they produce testosterone 5. Identify the parts of a mature sperm and state the function of each part. (8 marks) Head = contains DNA and the acrosomal cap that contains enzymes helps sperm to penetrate egg Mid-piece = contains mitochondria to provide ATP to power flagella movement Tail/Flagella = propels sperm 6. Explain how the hypothalamus and anterior pituitary gland function together to regulate sperm and testosterone production. Please explain the entire feedback loop using your own words/phrasing. (7 marks) The hypothalamus release Gonadotropin Releasing Hormone (GnRH) which then causes the anterior pituitary to release Follicle Stimulating Hormone (FSH) and Luteinizing Hormone (LH). FSH causes Sertoli cells of the testes to help sperm development while LH causes Interstitial (Leydig) cells of testes to release testosterone. Testosterone further stimulates Sertoli cell of testes to help sperm development. However, as testosterone levels rise they have a negative feedback effect on the hypothalamus and anterior pituitary such that the release of GnRH, LH and FSH are blocked. With these hormones blocked, less testosterone is released and testosterone levels begin to fall until they reach such levels that the negative feedback effect is lost and the cycle begins again, thus maintaining homeostasis within the male reproductive system. Page 23 of 28
7. Label the following diagram of the female reproductive system. Provide a brief description of each structure's function below the diagram. Please be neat. (10 marks) fimbriae oviduct ovary uterus cervix vagina Fimbriae = sweep egg into oviduct as it is released from the ovary Oviduct = typical site of fertilization, conducts egg to uterus Ovary = produce eggs and sex hormones (estrogen and progesterone) Uterus = site where fetus develops Cervix = entry way between vagina and uterus Vagina = receives penis during sexual intercourse, canal where menstrual fluid exit body, canal where fetus exits body Page 24 of 28
8. Give two ways that the oviduct aids the passage of the egg towards the uterus. (2 marks) - Mucous layer lining the oviduct secretes substances that aid in egg movement - Peristalsis (rhythmic contractions) move egg along the oviduct toward the uterus 9. List five different effects of estrogen on the female body. (5 marks) - Stimulates breast development during puberty - Stimulates maturation of uterus during puberty - Prepares uterus to nourish a developing fetus - Helps maintain bone density - Development of secondary sex characteristics of females including breasts, wider hips, greater fat deposition, development of arm pit and pubic hair 10. Complete the following table in relation to the female reproductive cycle. (13 marks) Hormone Full Name Source Effects GnRH Gonadotropin Releasing Hormone hypothalamus Causes pituitary gland to release LH and FSH FSH Follicle Stimulating Hormone Pituitary gland Causes ovaries to produce a mature follicle (egg) LH Luteinizing Hormone Pituitary gland Causes ovary to release egg Estrogen Estrogen ovary Lower levels stimulate endometrium development in uterus, high levels prevent GnRH release Progesterone Progesterone ovary Stimulates endometrium development in the uterus, high levels inhibit LH release Page 25 of 28
11. The Ovarian Cycle: a. Identify the name given to Days 1-13 of the ovarian cycle and describe the changes in hormones and ovarian structures that occurs during this time. (3 marks) = Follicular Phase = hypothalamus releases GnRH causing anterior pituitary to release FSH and LH which causes egg maturation b. Identify the name of the event that occurs on Day 14 of the ovarian cycle and specifically identify how hormone levels are responsible for influencing its occurrence. (2 marks) = Ovulation = egg released = high levels of LH trigger this event c. Identify the name given to Days 15-28 of the ovarian cycle and describe the changes in hormones and ovarian structures that occurs during this time. (3 marks) = Luteal Phase = corpus luteum secretes estrogen and progesterone which influence the uterine cycles = if pregnancy does not occur the corpus luteum disintegrates, estrogen and progesterone levels drop and menstruation (uterine cycle) occurs 12. The Uterine Cycle: a. Identify the name given to Days 1-5 of the uterine cycle and describe the changes in hormones and uterine structure that occurs during this time. (3 marks) = Menstruation = low levels of estrogen and progesterone lead to endometrium (lining of uterus) breaking down and being expelled from body b. Identify the name given to Days 6-13 of the uterine cycle and describe the changes in hormones and uterine structure that occurs during this time. (3 marks) = Proliferative Phase = increased production of estrogen by the maturing egg in the ovary lease to rebuilding of the endometrium in preparation for the potential of a fertilized egg implanting Page 26 of 28
c. Identify the name given to Days 15-28 of the uterine cycle and describe the changes in hormones and uterine structure that occurs during this time. (3 marks) = Secretory Phase = increased levels of progesterone released by the corpus luteum in the ovary causes the endometrium to double in thickness, become highly vascularized and to produce mucus such that it is ready to receive a fertilized egg (embryo) 13. Pregnancy and birth: a. Define implantation. (1 mark) = when a fertilized egg (embryo stage) embeds itself in the endometrium of the uterus several days after the fertilization event b. What hormone is released from the membrane surrounding the embryo to prevent corpus luteum from degenerating? (1 mark) = the Human Chorionic Gonadotropin hormone (HCG) which is what pregnancy tests are designed to detect c. Why is it important to prevent the corpus luteum from degenerating following implantation? (1 mark) = if the corpus luteum disintegrates too early the estrogen and progesterone levels will drop causing the endometrial lining (and the implanted embryo) to be shed effectively a miscarriage d. What tissues does the placenta originate from? What are the hormonal and physical functions of the placenta? (3 marks) = maternal and fetal tissues = produces HCG hormone to maintain the corpus luteum = movement of nutrients from mother's blood to fetal blood, movement of waste from fetal blood to mother's blood e. Why do the levels of estrogen and progesterone remain high during pregnancy and why is this important? (2 marks) = remain high due to maintenance of corpus luteum by HCG hormone (produced by placenta) = necessary to prevent shedding of the endometrial lining and developing fetus Page 27 of 28
f. What are the functions of the hormone oxytocin and where does in originate? Describe positive feedback as it relates to this hormone. (4 marks) = oxytocin causes the uterus to contract which then initiates a positive feedback loop causing further release of oxytocin and further contractions and so on until the baby is delivered = oxytocin also is released in response to a baby suckling and causes the mammary glands to release milk = oxytocin is released from the posterior pituitary Page 28 of 28