Access to HE Unit: BIO 100 Body System Coordination
Learning Outcome: LO4 (Human reproductive system)
To achieve level 3, address the questions correctly.
Level 3 (Assessment Criterion 4.1)
Q1The diagram below (Kent 2000) illustrates the human male reproductive system.
361188036556959. Scrotal sac
009. Scrotal sac
358330515411453. Prostate gland
003. Prostate gland
360743527222456. Vas deferens
006. Vas deferens
right9791702. Seminal vesicle
002. Seminal vesicle
360235520459704. Cowper’s gland
004. Cowper’s gland
Provide the missing labels on the diagram.
1. The bladder is made up of four layers; The serous, this is the outer layer that is an existing layer coming from the peritoneum (Kuchel and Hof, 2004). The detrusor muscle is part of the bladder wall, comprising of three layers together with longitudinal and circularly organised muscle fibres (Kuchel and Hof, 2004). The sub-mucous is a fine layer of connective tissue loosely connecting the muscular layer to the mucous layer (Kuchel and Hof, 2004). The mucous is the deepest layer of the wall of the bladder, which is loosely connected to the muscular layer (Kuchel and Hof, 2004). Once the bladder is empty or almost empty the mucosa cascades into numerous folds this is known as rugae (Kuchel and Hof, 2004).The function of the urinary bladder is to store urine before its removal from the body (Kuchel and Hof, 2004). During urination the bladder transports urine into the urethra, resulting in urine exiting the body (Kuchel and Hof, 2004). A small circular muscle at the entrance of the bladder closes the opening to the bladder when ejaculation occurs, so you it’s impossible to urinate whilst ejaculating (Kuchel and Hof, 2004). Elastic fibers and involuntary muscle fibers are in the wall of the urinary bladder these assist in its functions of enlarging to hold different amounts of urine and then contracting to empty (Kuchel and Hof, 2004).
2. The seminal vesicles consists of tubules these consist of three layers; the inner lining which is a folded mucous membrane, a muscle layer and a fibrous external layer which covers the elastic tissue (Rosdahl and Kowalski, 2008). Responsible for secreting the thick fluid made by the seminal vesicles is the mucous membrane (Rosdahl and Kowalski, 2008). In the process of ejaculation, the muscular tissue together with the elastic fibers contract to empty the vesicle’s volume into the ejaculatory ducts (Rosdahl and Kowalski, 2008).
3. The prostate is split into anatomical lobes, the inferoposterior, inferolateral, superomedial, and anteromedial by the urethra as they go through the organ (Patton and Thibodeau, 2016). The prostate secrets a thin fluid which contributes to the seminal fluid volume, this fluid encourages the spermatozoon motivation and sustains their motility (Patton and Thibodeau, 2016).
4.The Cowper’s glands are two small exocrine glands which are made up of
numerous lobules being kept together by a fibrous casing (Thibodeau and Patton (2013). Each duct gland opens into the penile area of the urethra which is at the bottom of the penis (Thibodeau and Patton (2013). Its function is to production of pre-ejaculate (Thibodeau and Patton (2013). This thick secretion is initiated by sexual arousal it aids in lubricating the urethra to enable spermatozoa to travel and neutralize any form of urine that’s acidic within the urethra (Thibodeau and Patton (2013).
5. There are three layers of the urethra, the muscular, erectile, and mucous, the muscular layer just being an extension of the bladder (McAnulty and Burnette (2006). The urethra allows urine to be emptied through it as well as semen during the ejaculation process (McAnulty and Burnette (2006). In men the urethra is split into four parts Pre-prostatic urethra, Prostatic urethra, Membranous urethra and Spongy urethra named after their location (McAnulty and Burnette (2006). The function of the urethra is to provide an exit for urine and semen during ejaculation (McAnulty and Burnette (2006).
6. Vas deferens are miniscule muscular tubes, these transport spermatozoon from the epididymis to the ejaculatory duct awaiting ejaculation (McAnulty and Burnette (2006). It is the transport system for the movement of spermatozoon (McAnulty and Burnette (2006). When ejaculation occurs a smooth muscle in the walls of the vas deferens contracts instantly, enabling the spermatozoon to be propelled forward (McAnulty and Burnette (2006).
7. There are three parts of the epididymis; the head, the body and the tail. It is in the form of a narrow, coiled tube connecting the efferent ducts from the rear of each testis to its vas deferens (Haschek et al., 2017).The sheer length of the epididymis allows storage space for the spermatozoon along with time to mature before they are realised (Haschek et al., 2017).The epididymis additional function is to absorb fluid along with adding substances to the seminal fluid to sustain the maturing spermatozoa (Haschek et al., 2017).
8. The testis are an organ which lies within the scrotum. Each testicle is encased by a tough fibrous capsule known as the tunica albuginea (Haschek et al., 2017). A number of fibrous septa divide the organ into lobules (Haschek et al., 2017). There are one to three coiled tubules referred to as the seminiferous tubules, in each lobule. These open into a system named the rete testis (Haschek et al., 2017). Little efferent ductules, join the rete testis to epididymis. Production of spermatozoa and androgens is the testis initial function (Haschek et al., 2017). A man never stops producing spermatozoa throughout his lifetime, and from one ejaculation thousands of spermatozoa can be produced (Haschek et al., 2017). Testis are also responsible for realising testosterone (Haschek et al., 2017).
9. The Scrotal sac is a fine external sac of skin, this splits into two parts, each part containing one of the two testes, glands responsible for producing spermatozoa and the epididymis which stores the spermatozoa (Haschek et al., 2017). Its function is to protect and enable enough time for spermatozoa to mature before exit whilst keeping a cool environment for the testis (Haschek et al., 2017).
Q2Spermatogenesis can be broken down into three key stages.
In the space below, analyse spermatogenesis by naming the three stages. Also provide brief notes on each stage, highlighting key processes and their relevance.
Spermatogenesis is the development of spermatozoa. It happens inside the testicles, specifically, in a round shaped structure of the testicles called seminiferous tubules (Sherwood., 2012). Once the spermatozoids are produced, they are transported to the centre point of the tubule with a specific end goal to be transported to the epididymis, where the spermatozoa progression process will go to its last stage (Sherwood., 2012). Spermatozoids are male gametes, male sex, reproductive cells (Sherwood., 2012). They are haploids meaning they contain half the DNA (Sherwood., 2012). When the spermatogenesis, takes place the 46 chromosome somatic cells are able to change into 23 chromosomes sexual cells (Sherwood., 2012).
a) Name of first stage: Proliferative phase
Notes on key processes:
Otherwise called the spermatogonic stage. Sort A spermatogonia are shaped from a germ mother cell that will divide mitotically to produce the sort B spermatogonia (Sherwood., 2012). When men get to puberty, these cells will divide several times to produce a spermatocyte cell (Sherwood., 2012). While the splits are underway some cell changes occur (Sherwood., 2012). This stage is known as proliferative stage due to the sheer amount of mitosis that takes place (Sherwood., 2012). The fundamental objective is to create however many spermatozoa precursor cells as possible, creating a high volume of spermatozoa (Sherwood., 2012).
Name of second stage: Meiotic phase
Notes on key processes:
The meiotic phase is also known as spermatocytegenesis. Within this stage, an alternate cell division happens (Sherwood., 2012). Such division is the meiosis, which splits the genetic information to the half, creating haploid cells called spermatids. Meiosis can be split into two sub stages (Sherwood., 2012). Meiosis I, is where primary spermatocytes split into two secondary spermatocytes (Sherwood., 2012). Meiosis II is where every secondary spermatocyte splits into two spermatids, creating four spermatids (haploid) are gotten from the first primary spermatocytes (diploid) (Sherwood., 2012). These cells are progressively starting to take after spermatozoa, they even have a little flagellum (Sherwood., 2012).
Name of third stage: spermatogenesis (Oliveira and Alves, 2015).
Notes on key processes:
Spermatogenesis is the last phase of the spermatozoa development process. The maturation of spermatids happens at this stage (Sherwood., 2012).The flagellum increases in size, offering rise to the flagellum that will permit its progression (Sherwood., 2012).On the other hand, the head containing the nucleus of the spermatozoa decreases in size and paddle-shaped, a component that happens due to the cytoplasm reduction, the nucleus enlarging and the acrosome creation (Sherwood., 2012).When spermiogenesis completes, spermatids are completely formed into spermatozoa and are discharged into the seminiferous tubule (Sherwood., 2012).
Level 3 (Assessment Criterion 4.2)
Q3The diagram below (Kent 2000) illustrates the human female reproductive system.
Provide the missing labels on the diagram.
The diagram contains an error with regards to the ureters. Can you briefly point out what this error is?
The ureter’s goes either side of the bladder and both should be the same length in the image above it appears as if both the ureters link and join to each other this is not the case (Clemente, 2011).
Q4Like spermatogenesis, oogenesis is broken down into three key stages.
In the space below, analyse oogenesis by naming the three stages. Also provide brief notes on each stage, highlighting key features and how they are different from spermatogenesis.
Oogenesis is the method of creating the female gametes, the Ovum, from the primordial germ cells (Browder, 1985). Most of the stages in oogenesis, up to the point of creating primary oocytes, happen pre-natally. Females are born with all the Primary Oocytes that they will ever have as primary oocytes don’t split further (Browder, 1985).No polar bodies are formed in spermatogenesis unlike oogenesis (Browder, 1985).
Name of first stage: Multiplication Phase
Notes on key features:
The primordial germinal cells split over and over again to frame the oogonia (Browder, 1985). The oogonia duplicate by the mitotic divisions and create the primary oocytes which go through the development stage (Browder, 1985).
Name of second stage: Growth Phase:
Notes on key features:
The growth stage of the oogenesis is relatively longer than the growth stage of the spermatogenesis (Browder, 1985). In the development stage, the span of the primary oocyte increases dramatically (Browder, 1985). The cytoplasm of the oocyte develops rich in RNA, DNA, ATP and enzymes (Browder, 1985). In the growth stage, dramatic changes additionally happen in the nucleus of the primary oocyte (Browder, 1985). The nucleus gets big because of the expanded measure of the nucleoplasm and is called germinal vesicle (Browder, 1985). The chromosomes change their shape and end up noticeably mammoth light brush chromosomes which are specifically related with expanded transcription of messenger RNA atoms and protein synthesis in the cytoplasm (Browder, 1985). At the point when the development of the cytoplasm and nucleus of the primary oocyte is finished, it is then ready to progress onto the maturation phase (Browder, 1985).
Name of third stage: Maturation Phase – Meiosis I
Notes on key features:
The maturation stage is assisted by the maturation or meiotic division (Browder, 1985). The maturation division of the primary oocyte varies dramatically from the maturation division of the spermatocyte (Browder, 1985). After this the meiotic division of the nucleus and the cytoplasm of the oocyte, divides unevenly to shape a single big haploid oocyte and three little haploid polar bodies or polocytes near the end (Browder, 1985). If equal division was to happen to the primary oocyte the stored food volume would result in being given to the four daughter cells, this may affect the development of the embryo by being inadequate (Browder, 1985). As a result, these unequal divisions grant one out of the four daughter cells to accommodate the majority of the cytoplasm, whilst reserving food which is adequate for the developing embryo (Browder, 1985). The homologous chromosomes of the primary oocyte nucleus travel through the pairing or synapsis, duplication, chiasma development and crossing over, this occurs within the first maturation division or first meiosis I (Browder, 1985). Next due to contraction of the chromonemal fibres the nuclear membrane splits and the bivalent chromosomes travel in the direction of the opposite poles (Browder, 1985). The endoplasmic reticulum forms a new nuclear envelope around the daughter chromosome (Browder, 1985). Once karyokinesis has done its job the unequal cytokinesis takes place, resulting in a small haploid polar body or polocyte, along with a big haploid, secondary oocyte or ootid are produced (Browder, 1985).
Meiosis II is the Second meiotic division (Browder, 1985). Travelling through this meiosis II phase is the haploid secondary oocyte together with the first polocyte (Browder, 1985). As a result of the Meiosis II, the secondary oocyte forms a mature oocyte and a second polocyte (Browder, 1985). By the meiosis II stage the first polocyte additionally divides into two secondary polocytes (Browder, 1985). These polocyte then overflow out of the oocyte and deteriorate, meanwhile the haploid oocyte is then ready got the fertilisation (Browder, 1985).
Level 3 (Assessment Criterion 4.3)
146056413500Q5 The process of fertilisation has five stages, labelled a, b, c, d and e in the diagram (Kent 2000). For each stage of the process, provide the name and briefly explain the key events and their functional importance.
Name of stage: Movement
Spermatozoa swim strongly in the direction of the oocyte and through the outer layers (Heffner and Schust, 2010). The underlying attraction of the spermatozoa towards the oocyte should be chmotactic (Heffner and Schust, 2010).
Name of stage: Capacitation
The spermatozoon swim towards the oocyte and collide with it. Normally several spermatozoa attach themselves to the oocyte (Heffner and Schust, 2010). Contact of the spermatozoa with the zona pellucida triggers the acrosome reaction (Heffner and Schust, 2010).
Name of stage: Penetration
Aided by the acrosome enzymes they dissolve the oocyte membrane allowing the spermatozoon entry to penetrate the zona pellucida (Heffner and Schust, 2010). It’s just the head containing the nucleus and middle of the spermatozoa that go inside the flagellum is left outside (Heffner and Schust, 2010).
Name of stage: Cortical reaction
Fusion of the spermatozoon surface membrane and that of the oocyte triggers the cortical reaction (Heffner and Schust, 2010). Cortical granules harden the zona pellucida, stopping any other spermatozoa from entering (Heffner and Schust, 2010).
Name of stage: Fusion
The spermatozoon nucleus is currently inside the ovum (Heffner and Schust, 2010). Formation of a diploid zygote is now underway as the nuclei of the ovum and spermatozoon fuse (Heffner and Schust, 2010).
Q6 The diagram below (Kent 2000) illustrates implantation.
Name the inner tissue (cell lineage) of the blastocyst: Embryoblast
Explain its function:
The embryoblast is the mass of cells inside the primordial embryo that, when fertilized, will in due course give rise to the definitive structures of the fetus (Mohan, Bajaj and Gundappa, 2018).When formation of the embryo has started it is covered with the amnion membrane (Mohan, Bajaj and Gundappa, 2018). This fills with amniotic fluid enabling the amnion to inflate becoming the amniotic sac delivering a protective environment for the progressing embryo (Mohan, Bajaj and Gundappa, 2018). The amnion, the chorion, the yolk sac and the allantois create a protective sac surrounding the embryo (Mohan, Bajaj and Gundappa, 2018).
Name the outer tissue (cell lineage) of the blastocyst: Trophoblast.
Explain its function:
The trophoblast creates the external layer of the blastocyst, giving the embryo supplements and giving rise to the external chorionic sac and the fetal part of the placenta (Mohan, Bajaj and Gundappa, 2018). The trophoblast encourages embryonic implantation by means of its inner layer of mononuclear cytotrophoblasts and its external layer of multinuclear cytoplasm, the syncytiotrophoblasts, this makes the early associations between the embryo and the maternal endometrium (Mohan, Bajaj and Gundappa, 2018).
Q7The diagram (Kent 2000) illustrates pregnancy in humans.
On the diagram, provide the missing labels.
In the space below, explain the contributions of fetus, amnion, chorion and allantois to the support of development in pregnancy.
The fetal embryo has extraembryonic membranes during development; the amnion, chorion allantois and yolk sac. The umbilical cord and the placenta are both outgrowth of these membranes (Jones and Lopez, 2006). The role of the placenta is to supply the fetus with nutrition and oxygen along with disposing the fetus’s waste. Connecting the embryo to the placenta is the umbilical cord (Jones and Lopez, 2006).
The outer most membrane the chorion encloses the entire embryo including the other membranes. The Chorion lines the amnion and the yolk sac become part of the placenta (Jones and Lopez, 2006).
The amnion is a membrane forming a fluid-filled buoyant cavity (the amniotic sac) that encases the embryo. The amniotic sac and the liquid it contains can be referred to as the bag of waters (Solomon et al., 2014).
During developed, the amnion emerges by a collapsing of a mass of additional embryonic tissue called the somatopleure. lined with ectoderm and secured with mesoderm, the amnion has a thin, see through liquid in which the embryo is suspended, consequently giving a cushion to prevent mechanical damage. The amnion additionally gives protection from liquid loss from the embryo (Solomon et al., 2014)
The allantois is an outgrowth of the developing digestive tract (Solomon et al., 2014). The allantois is small and doesn’t have a main function other than its blood vessel contributing to the formation of the umbilical vessels joining the embryo to the placenta. It is also a source of urinary bladder for the placenta (Solomon et al., 2014).
Level 3 (Assessment Criterion 4.4)
Q8The diagram (Kent 2000) shows an outline of the ovarian and uterine cycle.
Name the four hormones that occur in the diagram:
1 = Luteinizing hormone (Haschek et al., 2017).
2 = Follicle-stimulating hormone (Haschek et al., 2017).
3 = Progesterone (Haschek et al., 2017).
4 = Oestrogen (Haschek et al., 2017).
Use the information in the diagram to explain briefly how the ovarian cycle and the menstrual cycle are regulated by blood hormonal levels.
Ovulatory changes start on the first day of the menstrual cycle (Marieb, 2007). As the cycle starts, low Oestrogen along with progesterone levels in the bloodstream stimulate the hypothalamus to secret gonadotrophin-stimulating hormone (Gn-RH) (Marieb, 2007). In turn, Gn-RH stimulates the anterior pituitary gland to secrete follicle-stimulating hormone (FSH) and luteinizing hormone (LH) (Marieb, 2007). Follicle development inside the ovary is prompted by heightened levels of FSH and to a lesser degree LH (Marieb, 2007). At the point when the folic matures, a spike in the LH level happens, resulting in the follicle to rupture and discharge the ovum, in this way starting ovulation (Marieb, 2007). After ovulation in the luteal phase, the collapsed follicle forms the corpus luteum, this on the condition its fertilization doesn’t occur, degenerates (Marieb, 2007).
During the follicular phase of the ovarian cycle, the increasing FSH and LH levels which stimulate follicle growth also stimulate increased secretion of oestrogen (Marieb, 2007). Oestrogen secretion peak right before ovulation (Marieb, 2007). This peak starts the spike in LH levels, this results in ovulation (Marieb, 2007). After ovulation, Oestrogen levels decrease fast (Marieb, 2007). In the luteal phase of the ovarian cycle, the corpus luteum is made and starts to release progesterone and oestrogen (Marieb, 2007). As the corpus luteum degenerates, levels of both ovarian hormones decline (Marieb, 2007).
Reference (used in Task Book design)
Kent M (2000) Advanced Biology. Oxford: Oxford University Press.
Browder (1985). Oogenesis. Boston, MA: Springer US, pp.3-9.
Clemente (2011). Clemente’s anatomy dissector. Philadelphia: Wolters Kluwer Health / Lippincott Williams ; Wilkins, p.183.
Heffner and Schust,. (2010). The reproductive system at a glance. Chichester, West Sussex: Wiley-Blackwell p 40-43.
Haschek, Bolon, Rousseaux and Wallig (2017). Fundamentals of toxicologic pathology. S.l.: Elsevier Academic Press, p.464,465,470-475
Jones and Lopez (2006). Human Reproductive Biology. Burlington: Elsevier, pp.263-266.
Kuchel and Hof (2004). Autonomic nervous system in old age. Basel: Karger, p.78.
Marieb (2007). Human anatomy ; physiology. 7th ed. pp.1094-1099.
McAnulty and Burnette (2006). Sex and sexuality. Westport, CT: Praeger, pp.15-17.
Mohan, Bajaj and Gundappa (2018). Human amnion membrane: Potential applications in oral and periodontal field.
Oliveira and Alves (2015). Sertoli cell metabolism and spermatogenesis. pp.16,17.
Patton and Thibodeau (2016). Structure ; function of the body. St. Louis, Missouri: Elsevier. P 465
Rosdahl and Kowalski (2008). Textbook of basic nursing. Philadelphia: Lippincott Williams ; Wilkins, p.289.
SHERWOOD. (2012). FUNDAMENTALS OF HUMAN PHYSIOLOGY, 4th ed. BROOKS/COLE CENGAGE LEARNING, pp.552-555.
Solomon, Martin, Martin, Berg and Villee (2014). Biology. pp.1108-1109.
Thibodeau and Patton (2013). Structure ; Function of the Body. London: Elsevier Health Sciences, p.448.