BSCI202: Final Study Guide

What are the male primary sex organs (gonads) and their functions?

Testes: produce male gametes (spermatozoa) and male sex steroid hormones (androgens).

Name the male accessory reproductive ducts.

Epididymides (2), Vasa deferentia (2), Ejaculatory ducts (2), Urethra (1).

Name the male accessory reproductive glands.

Seminal vesicles (2), Prostate gland (1), Bulbourethral glands (2).

What is the membrane surrounding each testis?

Outer tunica vaginalis, inner tunica albuginea

Name the three cell types in the testis and their functions.

1. Spermatogenic cells: development stages within seminiferous tubules

2. Sustentacular (Sertoli) cells: support sperm development

3. Interstitial (Leydig) cells: produce androgens

Which testis cell type is endocrine and what stimulates it?

Interstitial (Leydig) cells; stimulated by LH to produce androgens

Name the three types of androgens.

DHEA, Androstenedione, Testosterone

Biological actions of testosterone is often converted to a more potent hormone by 5 alpha reductase called?

Dihydrotestosterone (DHT)

What are the prenatal biological actions of testosterone (DHT)?

Stimulates the differentiation of male internal and external genitalia

What are the postnatal biological actions of testosterone (DHT)?

Stimulates male secondary sex characteristics, linear bone growth (growth spurt), increased muscle mass, deepening of the voice, hair growth, and maintenance of spermatogenesis

What is the function of the scrotum?

Maintains intrascrotal temperature at 34°C (3°C below body temp), optimal for spermatogenesis.

Describe the cremaster and dartos muscle function in cold weather.

Cremaster contracts to pull scrotum closer to body for warmth; Dartos contracts to wrinkle skin and reduce heat loss.

Describe the cremaster and dartos muscle function in hot weather.

Both muscles relax; scrotum hangs lower to increase surface area and maximize heat loss.

What are the three phases of spermatogenesis?

Mitosis, Meiosis, Spermiogenesis

In spermatogenesis, what happens in mitosis?

Spermatogonium (2n) divides into Type A, replenishes stock and Type B cells (become primary spermatocytes)

In spermatogenesis, what happens in meiosis?

Primary spermatocytes (2n) undergo Meiosis I to form two haploid secondary spermatocytes (n), which then undergo Meiosis II to form four haploid spermatids

In spermatogenesis, what happens in spermiogenesis?

The physical maturation of round spermatids into streamlined spermatozoa

Where does spermatogenesis occur?

Seminiferous tubules

Which spermatogenic cells are diploid (2n)?

Spermatogonia and primary spermatocytes (46 chromosomes)

Which spermatogenic cells are haploid (n)?

Secondary spermatocytes, spermatids, and spermatozoa (23 chromosomes)

What is spermiogenesis?

The final phase of spermatogenesis, where non-motile spermatids transform into missile-shaped sperm capable of swimming

Where is testicular fluid made by, and what does it do?

Produced by sustentacular cells, it acts as a transport medium to flush sperm into the tubule lumen during spermiation

Describe the structure of a spermatozoon (sperm).

Head (haploid nucleus + acrosome with enzymes), midpiece (mitochondria for ATP), tail (flagellum for movement)

What is the blood-testis barrier?

Surrounds developing spermatogenic cells

What is the significance of the blood-testis barrier?

Prevents immune cells from attacking them (sperm develop after the immune system learns self)

What cells form the blood-testis barrier?

Sustentacular (Sertoli) cells

What is epididymal maturation?

Sperm spend 20 days in epididymides to mature, gaining rigid tail and ability to swim (only in the female tract)

Which male accessory duct serves as a sperm storage site and why?

Vasa deferentia (ductus deferentia); they store sperm and are cut during vasectomy for permanent birth control.

What is semen?

A mixture composed of sperm (male gametes) and the secretions from the male accessory reproductive glands

Where and how is semen formed?

Fluid is formed during ejaculation; formed in the ejaculatory ducts when they receive sperm from the vasa deferentia along with secretions from the seminal vesicles and the prostate gland.

Name chemicals in secretion from seminal vesicles (60% of seminal fluid).

Fructose, coagulating enzymes (vesiculase), ascorbic acid (vitamin C), prostaglandins

What chemical in the seminal vesicles provides the primary source of energy used by sperm for locomotion (swimming)?

Fructose

What chemical in the seminal vesicles causes the temporary coagulation of semen after ejaculation, which protects the sperm and initiates the process of capacitation?

Coagulating enzymes (Vesiculase)

What chemical in the seminal vesicles acts as an antioxidant and reducing agent to protect sperm from damage caused by oxidation?

Ascorbic acid (Vitamin C)

What chemical in the seminal vesicles facilitates sperm movement and transport through the female reproductive tract?

Prostaglandins

Name chemicals in secretion from prostate gland (33% of seminal fluid).

Citrate, fibrinolysin, acid phosphatase

What chemical in the prostate gland serves as a calcium chelator to help end the coagulation of semen?

Citrate

What chemical in the prostate gland is a liquefaction agent that breaks down the coagulated semen to release the sperm?

Fibrinolysin

What chemical is a unique enzyme that activates phospholipid metabolism in the prostate gland? Rising levels of this chemical in the blood can indicate growth of the prostate gland, such as Benign Prostatic Hyperplasia (BPH).

Acid phosphatase

Name chemicals in secretion from bulbourethral glands.

Thick alkaline fluid (pre-ejaculate) that neutralizes acidic urine residue in urethra

Which gland secretes acid phosphatase and what do rising levels indicate?

Prostate gland; rising levels indicate Benign Prostatic Hyperplasia (BPH). (Note: rising PSA indicates prostate cancer)

Describe the female primary sex organs (gonads) and their functions.

Ovaries (in pelvic cavity); oogenesis and production of estrogen and progesterone

Name the female accessory reproductive ducts.

Fallopian tubes, uterus, and vagina

List three structural differences between male and female reproductive structures.

1. Testes descend out of pelvic cavity; ovaries remain.

2. Male has penis; female has vagina.

3. Male ducts: epididymides, vasa deferentia, ejaculatory ducts, urethra; female ducts: fallopian tubes, uterus, vagina.

Which gonad is surrounded by the tunica vaginalis (outer and inner)?

The testis

What is oogenesis?

Process of creating a mature egg (ovum) in ovaries.

What is a primary oocyte?

A diploid cell formed when each oogonium begins the first meiotic division and gets arrested in prophase I

Name the four types of ovarian follicles.

Primordial, Primary, Secondary, Graafian (dominant)

What is a primordial follicle?

Primary oocyte surrounded by a single layer of squamous cells

What is a primary follicle?

Primary oocyte surrounded by at least two layers of cuboidal/columnar cells

What is a secondary follicle?

Primary oocyte surrounded by several layers of granulosa cells; fluid-filled vesicles appear; secretes high levels of estrogens (androgens from theca cells are aromatized to estrogens by granulosa cells)

What is a graafian (dominant) follicle

Contains a secondary oocyte (haploid, arrested in metaphase II) supported by cumulus oophorus, surrounded by zona pellucida, corona radiata, granulosa cells, and theca cells; it has a fluid-filled antrum.

Which ovarian follicle secretes estrogens? Which contains a secondary oocyte?

Secondary follicle (and Graafian); Graafian follicle contains secondary oocyte

What is a difference between oogenesis and spermatogenesis regarding number of gametes produced?

Spermatogenesis: 4 haploid spermatids from 1 primary spermatocyte. Oogenesis: 1 large secondary oocyte + 1 polar body.

What is an ovum?

The released secondary oocyte arrested in metaphase II (released during ovulation from the Graafian follicle)

What is known as the layer of cells immediately surrounding the zona pellucida of the ovum (part of the cumulus oophorus)?

Corona radiata

What is the glycoprotein layer surrounding the secondary oocyte, inside the corona radiata?

Zona pellucida

Where does normal fertilization occur? Is the zygote haploid or diploid?

Ampulla of the fallopian tube; zygote is diploid (2n)

How is zygote formed?

Haploid sperm and haploid ovum fuse

What is known as the early stage of embryo development consisting of 8-16 blastomeres, surrounded by intact zona pellucida; cells are compacted and polarized with basal and apical surfaces?

Morula

What is a blastocyst?

Early embryo stage of 32-64 blastomeres

What is the trophoblast of the blastocyst?

Single layer of blastomeres at the rim (microvilli on apical surface)

What is the pluriblast/Inner Cell Mass (ICM) of the blastocyst?

Aggregate of blastomeres eccentrically placed in the cavity

What is the blastocyst cavity (blastocoel) and what does it do?

Contains fluid; produces growth factors and hCG (from around 9 days post-fertilization)

Where does normal implantation occur? What conceptus that implants?

Endometrium of the uterus; the late blastocyst (after hatching from zona pellucida)

What is Human Chorionic Gonadotropin (hCG)?

A luteotrophic hormone produced by blastocyst (~9 days post-fertilization)

Why is hCG the basis for pregnancy tests?

Present only after implantation, so its presence indicates pregnancy

When does a true positive occur for a pregnancy test?

Around 14 days post-fertilization

What are two different ways a genetic male (XY) may present with a female-like external genitalia?

Androgen insensitivity syndrome (AIS) and 5 alpha reductase deficiency

What is Androgen Insensitivity Syndrome (AIS)?

Androgen receptor dysfunction. Genotype XY (male), phenotype XX (female). Also called testicular feminization.

What is 5 alpha reductase deficiency?

DHT not produced. Genotype XY (male), phenotype XX (female at birth, becomes male at puberty). Also called Guevedoces.

What is one way a genetic female (XX) may present with a male-like external genitalia?

Congenital adrenal hyperplasia (CAH)

What is Congenital Adrenal Hyperplasia (CAH) in genetic females?

Genotype XX (female) but phenotype XY (male-like external genitalia).

List all organs of the GI system.

Mouth, pharynx (oropharynx & laryngopharynx), esophagus, stomach, small intestine (duodenum, jejunum, ileum), large intestine (cecum, colon, rectum, anal canal), anus.

Name three accessory digestive organs of the oral cavity and their functions.

1. Teeth: mastication.

2. Salivary glands: secrete saliva and begin chemical digestion

3. Tongue: manipulates food and forms bolus

What is mastication?

The physical digestion or pulverization of large food substances into smaller ones

What glands make up salivary glands?

Parotid, submandibular, and sublingual glands

What are the functions of salivary glands?

They secrete saliva, which moistens food to form a bolus, cleanses the oral cavity, and begins chemical digestion

What is the function of the tongue and what does it contain?

Manipulates masticated food and mixes it with saliva to form the bolus for swallowing. It also contains papillae with taste buds to detect flavors.

Name the four types of teeth and their functions.

Incisors (8): biting.

Canines (4): tearing.

Premolars (8): grinding, crushing, chewing

Molars (12): grinding, crushing, chewing

What is the composition of saliva?

Water (99%), salivary amylase, lysozyme

What does water do in saliva?

Moistens food and dissolves food molecules so they can be tasted

What does salivary amylase do in saliva?

An enzyme that initiates the chemical digestion of starch and glycogen

What does lysozyme do in saliva?

Provides antimicrobial protection to the oral cavity

Why does chronic dry mouth cause halitosis (bad breath)?

Saliva cleanses the mouth; without its antimicrobial action (lysozyme) and physical flushing, odorous bacteria flourish.

Where does carbohydrate digestion begin?

In the oral cavity (mouth) with salivary amylase.

Name and describe the three phases of deglutition (including whether if they are voluntary or not)

1. Oral/Buccal (voluntary): tongue pushes bolus to oropharynx.

2. Pharyngeal (involuntary): uvula rises, epiglottis covers larynx.

3. Esophageal (involuntary): peristalsis moves bolus to stomach.

Voluntary; Only phase under conscious control. The bolus is formed, and the tongue pushes it against the hard palate, moving it toward the oropharynx. What deglutition phase is this?

Oral (Buccal) Phase

Involuntary; Once the bolus enters the pharynx, it is controlled by reflexes. The uvula and soft palate rise to close off the nasopharynx (preventing food from entering the nose), and the epiglottis covers the laryngeal opening to ensure swallowed substances have the "right of way" over airflow. What deglutition phase is this?

Pharyngeal Phase

Involuntary; The bolus enters the esophagus and is moved toward the stomach by peristalsis, which is the rhythmic, alternating contraction and relaxation of smooth muscles in the GI wall. What deglutition phase is this?

Esophageal phase

What is the two parts of the pharynx involved in deglutition?

Oropharynx and laryngopharynx

How is swallowed substances have right of way over airflow accomplished?

Uvula and soft palate block the nasopharynx; epiglottis covers laryngeal inlet, directing bolus to esophagus (respiratory tract temporarily closed)

Name the 4 layers of the GI wall.

Mucosa (innermost), Submucosa, Muscularis externa, Serosa (outermost)

What of the 4 layers of GI wall is the innermost layer, consisting of an epithelial lining, the lamina propria (areolar CT), and the muscularis mucosae?

Mucosa

What of the 4 layers of GI wall is a layer of CT containing blood vessels, lymph vessels, and glands?

Submucosa

What of the 4 layers of GI wall typically consists of two layers of smooth muscle—an inner circular layer and an outer longitudinal layer—responsible for motility?

Muscularis externa

What of the 4 layers of GI wall is the outermost covering, which is a continuation of the peritoneal membrane (visceral peritoneum)?

Serous

Name the two enteric plexuses and their locations.

Submucosal plexus (Meissner's): in submucosa. Myenteric plexus (Auerbach's): between muscle layers of muscularis externa

Define peristalsis.

Rhythmic, involuntary alternating contraction/relaxation of adjacent smooth muscle segments that propels food distally.

Define segmentation.

Nonadjacent GI segments contract and relax, moving food forward/backward to mix with digestive juices.