reproductive/lymphatic/immune (142)
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29 Terms
REPRODUCTIVE OBJECTIVES
define and use genetic terminology appropriately (gametes, fertilization, zygote, chromosomes, sister chromatids, homologous chromosomes, diploid, haploid, gene, allele)
Gametes are the specialized reproductive cells in humans. These include sperm in males and eggs (ova) in females. Each gamete carries only one set of chromosomes (haploid), meaning they contribute half the genetic material needed to form a new individual.
Fertilization is the process where a male gamete (sperm) and a female gamete (egg) fuse together. This event occurs in the female reproductive tract and results in the creation of a zygote. This union restores the diploid chromosome number, meaning the new cell now has a full set of chromosomes—half from each parent.
A zygote is the very first cell of a new organism. It forms immediately after fertilization and is diploid. It contains a complete set of chromosomes: 23 from the sperm and 23 from the egg, totaling 46 chromosomes.
Chromosomes are thread-like structures found within the nucleus of cells. They are made up of DNA, which carries the genetic instructions that direct the development and function of all living organisms. Humans have 46 chromosomes in each diploid body cell.
Sister chromatids are identical copies of a single duplicated chromosome. They form during DNA replication, just before a cell divides. These chromatids are joined together by a centromere and are eventually pulled apart during cell division.
Homologous chromosomes are a pair of chromosomes—one inherited from the mother and one from the father—that have the same structure and carry the same types of genes, but they may carry different versions of those genes (alleles).
A diploid cell contains two complete sets of chromosomes—one set from each parent. In humans, the diploid number is 46 (2n = 46).
A haploid cell has only one complete set of chromosomes. In humans, this means 23 chromosomes. Gametes are haploid because they must combine to form a diploid zygote during fertilization.
A gene is a segment of DNA located on a chromosome that codes for a specific protein or trait. Genes are the fundamental units of heredity.
An allele is a variant form of a gene. Since individuals inherit one copy of each gene from each parent, they can have identical or different alleles for each gene.
📝 Word-for-Word Notes from the PDF:
“Gametes: reproductive cells; sperm or egg”
“Fertilization: the union of sperm and egg”
“Zygote: the first cell formed after fertilization”
“Chromosomes: the structures that carry DNA (genetic material) within the nucleus of a cell”
“Sister chromatids: identical halves of a duplicated chromosome”
“Homologous chromosomes: a pair of matching chromosomes, one from each parent”
“Diploid: a cell with two sets of chromosomes, one from each parent”
“Haploid: a cell with one set of chromosomes”
“Alleles: the different forms of a gene”
“Humans have 46 chromosomes, 23 from mom and 23 from dad”
“They are diploid and have homologous pairs (same gene, different form of it)”
“Sex cells from each parent count as haploid, when together as a fertilized egg, they are diploid”
define meiosis and describe the events that occur in each stage of meiosis (prophase I & II, metaphase I & II, anaphase I & II, telophase I & II, cytokinesis)
✅ Paraphrased Notes (in my own words):
Meiosis is a special type of cell division that occurs only in the production of gametes—sperm and egg cells. Its purpose is to reduce the chromosome number by half, creating haploid cells (23 chromosomes each in humans) from an original diploid cell (46 chromosomes). This reduction is crucial because it ensures that when a sperm and egg fuse during fertilization, the resulting zygote has the correct number of chromosomes (46 total). Meiosis occurs in two successive stages: Meiosis I and Meiosis II, and each of these has sub-phases similar to mitosis.
🔹 Meiosis I – separation of homologous chromosomes:
Prophase I:
This is the first stage of meiosis I and one of the most complex. During this stage, the cell’s DNA has already been replicated.
Each chromosome is made up of two sister chromatids, joined at the centromere.
The nuclear envelope breaks down, allowing spindle fibers to interact with chromosomes.
Homologous chromosomes (one from each parent) come together and pair up side-by-side in a process called synapsis, forming tetrads.
Crossing over may occur here (though not detailed in the lecture notes), where chromatids exchange segments and create genetic diversity.
Centrosomes move to opposite poles and begin forming the spindle apparatus.
Metaphase I:
The paired homologous chromosomes (tetrads) align along the metaphase plate in the center of the cell.
Microtubules from the spindle fibers attach to the centromeres of each homologous chromosome pair.
This side-by-side alignment ensures that each new cell will receive just one chromosome from each homologous pair.
Anaphase I:
The spindle fibers begin to shorten, pulling the homologous chromosome pairs apart.
Each homolog moves to opposite poles of the cell, but the sister chromatids remain together at this stage.
This separation ensures that each resulting cell will be haploid, but still contain duplicated chromosomes.
Telophase I:
The separated homologous chromosomes reach the opposite poles of the cell.
A nuclear envelope may begin to reform around each new set of chromosomes.
The process of cytokinesis begins—this is when the cell’s cytoplasm divides.
This results in two new cells, each containing half the number of chromosomes, but with duplicated chromatids.
These cells are genetically different from one another because of the mixing of maternal and paternal chromosomes.
🔹 Meiosis II – separation of sister chromatids:
Prophase II:
Unlike Prophase I, there is no DNA replication before Prophase II.
The nuclear envelopes (if reformed in Telophase I) dissolve again, and the spindle fibers start to form.
Sister chromatids are still joined and preparing to be separated.
Metaphase II:
Chromosomes align again along the metaphase plate, but now the cell is haploid, and each chromosome consists of two sister chromatids.
Spindle fibers from each side of the cell attach to each chromatid at the centromere.
Anaphase II:
The centromeres split, and the sister chromatids are pulled apart to opposite ends of the cell.
This ensures each daughter cell ends up with a single chromatid from each chromosome.
Telophase II:
Chromatids reach the poles, and a new nuclear envelope reforms around each group.
Chromosomes begin to decondense.
Cytokinesis follows, dividing each of the two cells into two more cells.
At the end of meiosis II, there are four genetically unique haploid cells, each with 23 chromosomes.
describe the functional anatomy of the male reproductive structures (scrotum, testes, seminiferous tubules, interstitial cells, epididymis, spermatic cord, ductus deferens, ejaculatory duct, urethra, penis, seminal vesicle, prostate gland, bulbourethral gland, prostatic urethra, membranous urethra, spongy/penile urethra, glans penis)
Scrotum:
This is a sac of skin and connective tissue located outside the abdominal cavity.
It houses and protects the testes, keeping them at a temperature slightly lower than body temperature (~2–3°C cooler), which is essential for sperm development.
Functionally, it’s a continuation of the body wall that forms a pouch, which can contract or relax to regulate testicular temperature.
Testes:
These are the male gonads, and their primary function is to produce sperm and testosterone.
The seminiferous tubules inside the testes are the specific site where spermatogenesis (sperm production) occurs.
Spermatogenic cells line these tubules and develop into mature sperm.
Sustentacular (Sertoli) cells are also present and support developing sperm. They release androgen-binding protein (ABP), which keeps testosterone concentrated in the tubules.
Interstitial cells (Leydig cells) are located in the connective tissue between the seminiferous tubules and secrete testosterone in response to LH.
Epididymis:
A coiled tube sitting atop each testis.
It functions as a site of sperm maturation—sperm gain motility here.
It also serves as a storage reservoir for sperm, keeping them viable for several months.
Sperm exit the seminiferous tubules and enter the epididymis via small ducts for further development.
Spermatic Cord:
A bundle of nerves, connective tissue, blood vessels, and the ductus deferens that connects the testicles to the abdominal cavity.
It supports the testes structurally and allows them to receive blood, nutrients, and innervation.
Ductus Deferens (Vas Deferens):
A muscular tube that extends from the epididymis to the ejaculatory duct.
It serves as the main transport pathway for sperm during ejaculation.
Peristaltic contractions push sperm forward toward the urethra.
Ejaculatory Duct:
This is the short duct formed by the merging of the ductus deferens and the duct from the seminal vesicle.
It empties sperm and seminal fluid into the prostatic urethra.
Urethra (3 regions):
A shared passageway for both urine and semen, extending from the bladder to the external urethral orifice.
Prostatic urethra – passes through the prostate gland.
Membranous urethra – a short segment between the prostate and penis attachment.
Spongy (penile) urethra – runs the length of the penis and ends at the external urethral orifice.
Penis:
Male copulatory (sex) organ that delivers sperm into the female reproductive tract.
Internally contains erectile tissues that fill with blood to produce an erection.
The deep arteries located in the corpora cavernosa dilate to facilitate erection.
The corpus spongiosum surrounds the urethra and prevents it from collapsing during erection.
The glans penis is the enlarged tip of the penis and is the most sensitive part for sexual stimulation.
Seminal Vesicles:
Paired glands that secrete 60-70% of seminal fluid into the ejaculatory duct.
Their secretion is alkaline, contains fructose for energy, and prostaglandins which stimulate smooth muscle contractions in the reproductive tracts of both sexes to help sperm movement.
Prostate Gland:
Surrounds the prostatic urethra and contributes to 30% of seminal fluid.
Secretes a milky, slightly acidic fluid containing:
Citrate (for energy)
Proteolytic enzymes
Prostate-specific antigen (PSA) – breaks down semen in the female tract
Antibiotics
Enlarged prostates can press on the urethra, causing urinary symptoms.
PSA levels are used in detecting prostate cancer.
Bulbourethral Glands (Cowper’s glands):
Tiny, pea-sized glands beneath the prostate that secrete into the membranous urethra.
They produce alkaline mucus, which neutralizes traces of acidic urine in the urethra and provides lubrication for sperm passage.
Their secretions occur before ejaculation.
📝 Word-for-Word Notes from the PDF:
“Scrotum - Skin and body tissue that surrounds/contains the testes; fold of body wall”
“Seminiferous tubules: testes house these…where sperm is produced (spermatogenesis)”
“Interstitial cells: cells surrounding the seminiferous tubules, they produce testosterone”
“Spermatogenic cells are inside the tube, they become sperm cells…”
“Sustentacular cells…supporting cells…help the interstitial cells by producing and releasing androgen binding protein”
“Epididymis…a coiled tube which sits above the testes…complete maturation (become motile), held here until ejaculation…”
“Spermatic cord - a tube shaped structure of connective and nervous tissue…”
“Vas deferens…empties into the urethra below the bladder…muscular tube…”
“Urethra…exit point for sperm, seminal fluid, and urine. 3 parts: prostatic, membranosis, and penile…”
“Penis…blood vessels within it dilate for reproduction…deep arteries…corpora cavernosa…erection…corpus spongiosum…keeps urethra open…”
“Seminal vesicles…secretes most of the (seminal) fluid…alkaline…fructose…prostaglandins…”
“Prostate…secretes into the prostatic urethra…citrate…enzymes + antibiotics…PSA”
“Bulbourethral…pea sized…secretes first…alkaline…lubricating components for the urethra”
explain the composition of seminal fluid (include the secretions for the accessory glands: seminal vesicles, prostate gland and bulbourethral gland)
Seminal fluid, also called semen, is a combination of sperm cells and secretions from three accessory glands: the seminal vesicles, prostate gland, and bulbourethral glands. These fluids nourish, protect, and assist the movement of sperm.
Seminal Vesicles:
Paired glands that contribute 60–70% of the total semen volume.
Their fluid is alkaline, which helps neutralize the acidity of the male urethra and female reproductive tract.
Contains fructose, which serves as an energy source for sperm to produce ATP needed for motility.
Contains prostaglandins, which stimulate smooth muscle contractions to help sperm travel through the reproductive tracts.
Prostate Gland:
Encircles the upper urethra; its ducts empty into the prostatic urethra.
Contributes 25–30% of the semen volume.
Produces a milky, slightly acidic secretion with:
Citrate for energy
Enzymes
Antibiotics for protection
Prostate-specific antigen (PSA) to help liquefy semen after ejaculation in the female tract.
Bulbourethral Glands (Cowper’s glands):
Small, pea-sized glands located below the prostate.
Secrete alkaline mucus into the membranous urethra just before ejaculation.
Helps neutralize traces of acidic urine in the urethra and provides lubrication for the passage of sperm.
📝 Word-for-Word Notes:
“Seminal vesicles…secretes most of the (seminal) fluid…alkaline, contains fructose…contain prostaglandins…”
“Prostate…secretes…citrate…enzymes + antibiotics…prostatic specific antigens…”
“Bulbourethral…secretes first…alkaline…lubricating components for the urethra”
outline the steps involved in spermatogenesis. You must identify the stages of the sperm cells (spermatogonium, primary spermatocyte, secondary spermatocyte, spermatid, spermatozoa) as well as whether the cell is haploid or diploid
Paraphrased Notes:
Spermatogenesis is the process of creating mature male gametes (sperm) from stem cells called spermatogonia.
Begins at puberty and continues throughout life. Males produce ~400 million sperm per day.
Occurs in the seminiferous tubules of the testes.
Spermatogonium (Diploid – 2n, 46 chromosomes)
Stem cell that divides by mitosis.
Produces:
Type A cells: remain stem cells
Type B cells: commit to meiosis and become primary spermatocytes
Primary Spermatocyte (Diploid – 2n)
Enters meiosis I, homologous chromosomes separate.
Secondary Spermatocyte (Haploid – n, 23 chromosomes)
After meiosis I, now contains half the chromosomes.
Enters meiosis II, separating sister chromatids.
Spermatid (Haploid – n)
Results from meiosis II.
Round and non-motile at this stage.
Spermatozoa (Haploid – n)
Mature, motile sperm.
Undergo spermiogenesis to develop a tail and compact head.
📝 Word-for-Word Notes:
“Spermatogonia…stem cells that replace themselves by undergoing mitosis…”
“Primary spermatocytes…Type B: migrate toward center…still 46 chromosomes (diploid number)”
“Secondary spermatocytes: these are after the cells undergo meiosis I…now only containing 23”
“Spermatids: the cells after the sister chromatids separate in meiosis 2”
“Spermatozoan…going from a spermatid…to spermatozoa…head contains 23 chromosomes…mid piece has mitochondria…tail for movement”
explain the maturation of sperm cells (spermiogenesis) including the development of a head, tail and midpiece and the function of each part
Spermiogenesis is the final phase of spermatogenesis where a spermatid becomes a spermatozoon (sperm cell).
Key structural changes include:
Head:
Contains a nucleus with the sperm's 23 chromosomes.
Covered by the acrosome, which has digestive enzymes needed to penetrate the egg.
Midpiece:
Packed with mitochondria to generate ATP for tail movement.
Tail (flagellum):
Formed from the cell’s cytoskeleton.
Enables motility, allowing the sperm to swim toward the egg.
Excess cytoplasm is removed to create a streamlined, compact shape optimized for travel.
📝 Word-for-Word Notes:
“Spermiogenesis is the process of going from a spermatid…to spermatozoa”
“Head contains nucleus and acrosome”
“Midpiece: mitochondria”
“Tail: locomotion”
trace the path of sperm and seminal fluid through the male reproductive tract
Seminiferous tubules – sperm production begins here in the testes.
Epididymis – sperm mature and are stored.
Ductus deferens (vas deferens) – carries sperm up toward the bladder.
Ejaculatory duct – formed when vas deferens meets duct of seminal vesicle.
Prostatic urethra – receives secretions from prostate gland.
Membranous urethra – short segment.
Spongy/penile urethra – receives fluid from bulbourethral glands, ends at external urethral orifice.
📝 Word-for-Word Notes:
“Sperm is produced in the seminiferous tubules…go to the epididymis…then to ductus deferens…then into the ejaculatory ducts…then into the prostatic urethra…membranous urethra…spongy urethra…urethral orifice”
“Seminal vesicles…empties into the ejaculatory duct”
“Prostate gland empties into prostatic urethra”
“Bulbar urethral…empties into spongy urethra”
explain the first, second, and third tier of hormone control (GNRH, FSH, LH, testosterone, ABP) of male reproduction including the feedback mechanisms
First Tier: GnRH (gonadotropin-releasing hormone) from the hypothalamus begins being secreted at puberty, triggering the rest of the hormonal cascade.
Second Tier:
FSH (from anterior pituitary): stimulates sustentacular cells in the seminiferous tubules to produce ABP (androgen-binding protein) which binds testosterone and maintains high local levels in the testes.
LH (from anterior pituitary): stimulates interstitial cells to produce testosterone.
Third Tier:
Testosterone: promotes spermatogenesis, sexual development, and secondary sex characteristics.
Negative Feedback: High levels of testosterone and inhibin slow GnRH, LH, and FSH release.
📝 Word-for-Word Notes:
“First Tier: Gonadotropin-releasing hormone from hypothalamus…”
“FSH: stimulates supporting cells…to release androgen-binding protein (ABP)”
“LH: causes release of testosterone…from interstitial cells”
“Testosterone stimulates maturation…negative feedback loop…inhibits FSH and LH”
describe the parasympathetic (arousal) and sympathetic (ejaculation) control over the male sexual response
The male sexual response has two distinct phases:
1. Arousal (erection) – controlled by the parasympathetic nervous system
2. Ejaculation – controlled by the sympathetic nervous system
🔹 Arousal Phase – Parasympathetic control:
Parasympathetic signals cause smooth muscle relaxation in the arterioles of the corpora cavernosa, the paired erectile tissues in the penis.
This vasodilation allows blood to fill these tissues, leading to engorgement and erection.
Bulbourethral glands are activated early in arousal to lubricate the glans penis and neutralize acidity in the urethra.
As parasympathetic input increases, it primes the system for ejaculation by setting the stage.
🔹 Ejaculation Phase – Sympathetic control:
Once arousal reaches a critical threshold, sympathetic nerves take over.
Sympathetic input triggers powerful rhythmic muscular contractions of the:
Vas deferens
Seminal vesicles
Prostate
These contractions propel sperm and seminal fluid through the urethra in a forceful emission: ejaculation.
📝 Word-for-Word Notes:
“Arousal: Parasympathetic reflex causing relaxation of smooth muscle in arterioles in the corpora cavernosa…”
“Bulbourethral glands stimulated to lubricate glans penis…”
“Ejaculation: Sympathetic control once a threshold of arousal reached…”
“Muscular contraction”
describe the functional anatomy of the female reproductive structures (ovaries, uterine tubes, follicles, corpus luteum, uterus – endometrium, myometrium, perimetrium, cervix, vagina, external genitalia, mammary glands)
Ovaries:
Female gonads, located laterally to the uterus.
Site of egg (oocyte) production and hormone secretion (estrogen and progesterone).
Disorders like PCOS involve overproduction of androgens and cyst formation.
Uterine (fallopian) tubes:
Tubes that carry the ovulated oocyte from the ovary to the uterus.
Finger-like fimbriae sweep the egg into the tube.
Fertilization usually occurs here.
Follicles:
Fluid-filled structures in the ovary where oocytes mature.
Granulosa cells secrete estrogen.
Corpus luteum:
Remains of the follicle after ovulation.
Secretes estrogen and progesterone to prepare uterus for implantation.
Uterus:
Hollow organ with three layers:
Endometrium – inner lining with:
Stratum functionalis – sheds during menstruation
Stratum basalis – regenerates functionalis
Myometrium – thick smooth muscle layer
Perimetrium – outer serous membrane
Cervix:
Neck of the uterus; dilates during labor.
Produces mucus plug to block entry after fertilization.
Vagina:
Muscular tube (~8–10 cm); female copulatory organ.
Lined with stratified squamous epithelium for protection.
External genitalia (vulva):
Labia majora/minora – protective skin folds.
Clitoris – erectile tissue rich in blood vessels.
Perineum – supports pelvic floor muscles.
Mammary glands:
Modified sweat glands that secrete milk after childbirth.
Breast cancer is a major concern due to easy metastasis.
📝 Word-for-Word Notes:
“Ovaries…produces estrogen and progesterone…sight of egg production…”
“Uterine tubes…fimbriae…works as a vacuum…”
“Follicle cells secrete estrogen…become the corpus luteum”
“Endometrium…stratum functionalis…stratum basalis…”
“Myometrium: muscle…Perimetrium: outermost”
“Cervix…dilates before birth…secretes a mucus plug”
“Vagina…tube…copulatory organ…strat squam epi”
“External genitalia…labia…clitoris…perineum”
“Mammary glands…secrete milk…modified sweat glands”
outline the steps involved in oogenesis. you must identify the stages of the eggs cells (oogonium, primary oocyte, secondary oocyte, ovum, polar bodies) and whether the cell is haploid or diploid and the stages of follicle development (primordial follicle, primary follicle, secondary follicle, vesicular follicle, corpus luteum, corpus albicans)
Oogonium (Diploid): Stem cells in the ovary formed before birth.
Before birth, oogonia undergo mitosis and become primary oocytes, which are arrested in prophase I.
At puberty, FSH and LH stimulate a few primary oocytes each month to resume meiosis.
They complete meiosis I, producing one large secondary oocyte and a small polar body.
The secondary oocyte halts in metaphase II.
If sperm fertilizes the secondary oocyte, it completes meiosis II, forming an ovum and another polar body.
Follicle development:
Primordial follicle – primary oocyte + flat follicle cells (before birth)
Primary follicle – granulosa cells become cuboidal
Secondary follicle – multiple granulosa layers, secretes estrogen
Vesicular follicle – one dominant follicle, primary oocyte becomes secondary
Ovulation – release of secondary oocyte (arrested in metaphase II)
Corpus luteum – secretes estrogen + progesterone
Corpus albicans – degenerated corpus luteum (if no fertilization)
📝 Word-for-Word Notes:
“Oogonia: diploid (all 46)…before birth…become primary oocytes”
“Primary oocytes (arrested at prophase I)…250,000 at puberty”
“Secondary oocyte…arrested at Metaphase II…only completes meiosis II if fertilized”
“Primordial follicle…Primary…Secondary…Vesicular…Corpus luteum…Corpus albicans”
compare and contrast spermatogenesis and oogenesis. reflect upon differences in the timing of the meiotic divisions, cell size, and # of cells produced
Spermatogenesis:
Continuous from puberty onward.
Millions of sperm produced daily.
Each spermatogonium → 4 viable sperm.
Equal division of cytoplasm.
Motile cells.
Oogenesis:
Begins before birth, paused for years.
Finite number of oocytes (250,000 at puberty).
One oogonium → 1 ovum + 2 polar bodies.
Unequal cytoplasmic division (ovum gets all).
Large, non-motile egg.
📝 Word-for-Word Notes:
“oogonia…before birth…become primary oocytes…”
“Spermatogonia…continuously divide at puberty…”
“In oogenesis, primary oocyte divides unequally…1 large haploid cell + polar body…”
explain the first, second, and third tier of hormone control (GNRH, FSH, LH, estrogen) of female reproduction including the feedback mechanisms
First Tier: Hypothalamus releases GnRH at puberty.
Second Tier: GnRH stimulates anterior pituitary to release:
FSH: matures follicles and stimulates estrogen release from granulosa cells.
LH: causes ovulation and formation of corpus luteum.
Third Tier:
Estrogen: thickens uterine lining; high estrogen triggers LH surge.
Progesterone: maintains endometrial lining post-ovulation.
Negative feedback regulates GnRH, FSH, and LH levels.
📝 Word-for-Word Notes:
“First Tier: GnrH…released at puberty”
“FSH: causes follicle cells to mature and secretion of estrogen”
“LH: causes ovulation”
“Estrogen and progesterone act on the uterus…estrogen causes LH surge”
connect the events in the uterus with the events in the ovarian cycle during and explain how this is regulated by hormones (menstrual phase, proliferative phase, ovulation, secretory phase)
Days | Uterine Phase | Ovarian Phase | Hormones + Events |
|---|---|---|---|
1–5 | Menstrual | Follicular (early) | Low estrogen/progesterone → shedding of stratum functionalis |
6–14 | Proliferative | Follicular (late) | Rising estrogen rebuilds endometrium; dominant follicle matures |
14 | Ovulation | Ovulation | LH surge causes oocyte release |
15–28 | Secretory | Luteal | Progesterone from corpus luteum thickens lining |
If no fertilization: corpus luteum → corpus albicans → hormone drop → menstruation.
If fertilized: embryo releases hCG, maintains corpus luteum.
📝 Word-for-Word Notes:
“Days 1–5…shedding of stratum functionalis…”
“Days 5–14…stratum functionalis is rebuilt…”
“Day 14…LH surge causes ovulation…”
“Day 15–28…corpus luteum secretes progesterone…stratum functionalis secretes nutrients”
explain the parasympathetic and sympathetic regulation of the female sexual response
Paraphrased Notes:
Parasympathetic (arousal):
Increases blood flow to vulva and breasts, causing engorgement.
Vaginal walls secrete fluids for lubrication.
Sympathetic (orgasm):
Triggers muscle contractions, especially of the uterus and pelvic floor.
Heightened muscle tension may assist sperm transport.
📝 Word-for-Word Notes:
“Arousal: vulva and breasts engorge with blood”
“Orgasm: muscle tension increases and uterus contracts”
LYMPHATIC & IMMUNE SYSTEM OBJECTIVES
explain the three functions of the lymphatic system (drainage, lipids, immunity)
Drainage of Interstitial Fluid
One of the lymphatic system’s main roles is to collect excess fluid that leaks from blood capillaries into surrounding tissues (called interstitial fluid) and return it to the bloodstream.
Without this drainage, fluid would accumulate in tissues and cause swelling (edema).
Absorption and Transport of Lipids
The lymphatic system includes specialized capillaries called lacteals in the small intestine.
These lacteals absorb dietary lipids (fats) and lipid-soluble vitamins from digested food and transport them into the bloodstream via lymph.
Immunity
The lymphatic system produces, stores, and supports immune cells such as lymphocytes (B and T cells).
These immune cells help recognize and destroy foreign invaders (like bacteria and viruses), as well as clean up damaged or dead tissue.
Lymph nodes act as filters where immune responses are activated.
📝 Word-for-Word Notes:
“1. Drains/picks up excess interstitial fluid”
“2. Transports absorbed lipids through their own capillaries from the digestive system”
“3. Immunity: develops and matures immune cells, fights pathogens, cleans up damaged tissue”
describe the general composition of lymph and its formation at capillary beds, entry into lymphatic capillaries and its circulation through the lymphatic system (interstitial fluid, lymphatic capillaries, lymphatic vessels, lymph nodes, lymphatic trunks, right lymphatic duct, cisterna chili, thoracic duct)
Lymph Composition:
Lymph is a clear fluid similar to plasma but with less protein.
It contains water, electrolytes, waste, and immune cells like lymphocytes.
Formation:
Blood capillaries leak plasma into tissue spaces forming interstitial fluid.
When pressure builds in the tissues, this fluid is pushed into lymphatic capillaries, becoming lymph.
Flow of Lymph:
Lymphatic Capillaries:
Start as blind-ended tubes in tissues.
Made of overlapping endothelial cells that open when interstitial pressure increases—like trap doors.
Anchored by collagen and elastic fibers.
Lacteals: special capillaries in intestines that absorb dietary fat.
Lymphatic Vessels:
Collect lymph from capillaries.
Have valves to prevent backflow.
Lymphatic Trunks and Ducts:
Larger vessels formed from lymphatic vessels.
Two major ducts:
Right lymphatic duct: drains upper right side of body.
Thoracic duct: drains rest of body.
Cisterna chyli: enlarged beginning of thoracic duct near intestines.
Return to Bloodstream:
Both ducts drain into subclavian veins to return lymph to circulation.
Lymph Movement Aided By:
Skeletal muscle pump: muscle contraction pushes lymph.
Respiratory pump: thoracic pressure changes move lymph.
📝 Word-for-Word Notes:
“Formation: blood capillaries leak out fluid…capillaries fill…puts pressure on the lymphs which cause it to take the blood up”
“Lymphatic capillaries: closed at one end…endothelial cells…act like a trapped door…anchored by collagen and elastic fibers”
“Lacteals: carries lipids near the small intestine”
“Right lymphatic duct: upper right body”
“Thoracic duct: main duct for return to the blood”
“Cisterna chili: beginning of the thoracic duct”
“Skeletal pump: massaging/kneading/milking the lymphatic vessels…”
“Respiratory pump: pressure changes in thoracic cavity helps the lymph move…”
describe the general location and function of the cells of the lymphatic system (B lymphocytes, T lymphocytes, natural killer cells, macrophages, dendritic cells, reticular cells)
B Lymphocytes (B Cells):
Found in lymph nodes, spleen, and plasma.
Responsible for antibody-mediated (humoral) immunity.
Once activated, they produce plasma cells (which make antibodies) and memory B cells.
T Lymphocytes (T Cells):
Also located in lymphatic organs.
Mediate cellular immunity by attacking infected or abnormal cells.
Include T helper cells (CD4) and T cytotoxic cells (CD8).
Natural Killer Cells (NK Cells):
Large, fast-acting lymphocytes.
Constantly patrol the body, killing virus-infected and cancerous cells without prior activation.
Macrophages:
Derived from monocytes.
Act as phagocytes, engulfing pathogens and debris.
Dendritic Cells:
Use receptor-mediated endocytosis to capture antigens.
Act as APCs (antigen-presenting cells) to T cells.
Reticular Cells:
Produce reticular fibers, forming the scaffolding that supports lymphoid tissues.
📝 Word-for-Word Notes:
“Lymphocytes: white blood cells with large nuclei…B and T activate to fight pathogens…very sit and wait”
“B cells: make ope] cells”
“T cells: manage immune response”
“Natural killer: survey body”
“Macrophages: phagocytosis of foreign material”
“Dendritic cells: receptor-mediated endocytosis”
“Reticular cells: make the framework for the rest of the cells”
describe the structure and function of the primary lymphatic organs; bone marrow (red bone marrow, stem cells) and thymus (capsule, cortex, medulla, Hassall’s corpuscle).
Bone Marrow (Red):
Site of hematopoiesis: produces all blood cells including B cells and T cell precursors.
B cells mature here.
Red marrow dominates in children; yellow marrow (fatty) increases with age.
Thymus:
Located in the mediastinum, above the heart.
Primary site for T cell maturation.
Most active in children and shrinks with age.
Has:
Capsule – protective outer layer
Cortex – contains immature T cells
Medulla – contains mature T cells
Hassall’s corpuscles – remove T cells that recognize self-antigens, preventing autoimmunity.
📝 Word-for-Word Notes:
“Bone marrow…produces WBC and RBC…more red when younger and yellow when older”
“Thymus…where T cells mature…Capsule…Cortex: immature T cells…Medulla: mature T cells…Hassall’s corpuscle: makes sure T cells do not bind to normal things…”
describe the structure and function of the secondary lymphatic organs; lymph nodes (capsule, cortex, subcapsular sinus, trabeculae, medulla, lymph sinus), spleen (capsule, white pulp, red pulp), tonsils (tonsillar crypts), appendix, and Peyer’s Patches
Lymph Nodes:
Small, bean-shaped organs located along lymphatic vessels (~600 in the body).
Act as filters that clean lymph before it returns to circulation.
Capsule: Dense connective tissue covering the node.
Trabeculae: Extensions of the capsule that project into the interior for structural support.
Subcapsular sinus: A space beneath the capsule containing reticular fibers, macrophages, and dendritic cells; this is the first region lymph enters and encounters immune cells.
Cortex: Outer region packed with B cells (lymphocytes), situated below the capsule and sinus; responsible for initial immune activation.
Medulla: Inner part that contains B cells, plasma cells (antibody producers), and macrophages.
Spleen:
Largest lymphatic organ, located on the left side of the abdomen.
Functions include lymphocyte proliferation, blood filtration, debris removal, and storage of iron and platelets.
Capsule: Dense connective tissue surrounding the organ.
White pulp: Contains lymphocytes and reticular fibers surrounding central arteries—this is the immune component.
Red pulp: Filled with macrophages, blood-filled sinuses, and red blood cells; this region is responsible for RBC breakdown and recycling.
Tonsils:
Collections of lymphatic tissue in the oral and nasal regions.
Types: Palatine, lingual, and pharyngeal (also called adenoids).
Contain follicles with germinal centers where B cells proliferate.
Tonsillar crypts: Indentations that trap bacteria and foreign materials; serve as sites for antigen exposure and WBC action.
Appendix:
A narrow pouch attached to the cecum of the large intestine.
Contains follicles of lymphoid tissue in its walls that support immune functions in the gut.
Peyer’s Patches:
Clusters of lymphoid follicles in the walls of the small intestine.
They serve as immune surveillance points in the digestive tract, detecting pathogens in consumed food.
Word-for-Word Notes
“Lymph nodes: Secondary bean shaped nodules in lymphatic vessels, about 600. ‘filters’ the lymph before it returns to the blood. Help activate the immune system.”
“Capsule: dense connective tissue. Trabeculae: extensions of the capsule into the node… Subcapsular sinus: reticular fibers, macrophages, dendritic cells… Medulla: inner region… B cells and plasma cells… Cortex: Outer region, B cells.”
“Spleen: lymphocyte proliferation and monitoring of system, cleanses blood debris and microorganisms (1) Stores iron (2) Stores blood platelets (3) Erythrocyte production in fetus.”
“White pulp: reticular fibers supporting lymphocytes… surround arteries in spleen. Red pulp: blood sinuses, macrophages etc…, RBC disposal.”
“Tonsils… ring of tissue around pharynx… follicles with germinal centers of B cells. Tonsillar crypts: bacteria and foreign material gets stuck… WBC are [here].”
“Peyer’s patches: clusters of lymphoid follicles in the wall of small intestine.”
“Appendix: follicles clustered in wall of appendix.”
briefly distinguish among the innate and adaptive immunity and state which are innate or adaptive (surface barriers, internal defenses, humoral/antibody immunity and cellular immunity)
Innate (nonspecific) immunity:
Present at birth, provides a generalized, immediate defense against pathogens.
Responds the same way to all threats; does not have memory.
Includes surface barriers and internal defenses.
Components:
Surface barriers (first line): skin, mucous membranes, secretions.
Internal defenses (second line): phagocytes, natural killer cells, inflammation, fever, antimicrobial proteins.
Adaptive (specific) immunity:
Develops after exposure to specific pathogens.
Is slower to act but has memory and is antigen-specific.
Involves B cells (antibody/humoral immunity) and T cells (cellular immunity).
Produces targeted responses and long-lasting protection.
Word-for-Word Notes
“Innate/Nonspecific: born with this set of defenses.”
“Adaptive: specific response to a specific microbe.”
“Innate Defenses: Surface Barriers: first line of defense.”
“Internal Defenses: second line of defense.”
“Activation of Cell Mediated Immunity: cells (T cells) protect the body directly.”
“Activation of Antibody-Mediated Immunity/Humoral Immunity: antibodies mark antigens for destruction.”
describe the first line of innate defenses (mechanical barriers, acidic secretions, lysozymes, mucus production, and expulsion)
The first line of defense includes physical and chemical barriers that prevent pathogen entry.
Mechanical barriers: Skin and mucous membranes form the body’s outer defense wall, providing a continuous, protective surface.
Acidic secretions: Skin and mucosal surfaces release acids that lower pH, creating a hostile environment for microbes.
Lysozymes: Enzymes found in tears, saliva, and other secretions break down bacterial cell walls.
Sticky mucus: Found in respiratory and digestive tracts; traps pathogens and particles.
Expulsion mechanisms: Coughing, sneezing, vomiting, and diarrhea work to physically expel pathogens and irritants.
Word-for-Word Notes
“Surface Barriers: first line of defense.”
“Mechanical barriers: skin and mucus membranes.”
“Acidic secretions.”
“Lysozymes: enzyme destroys bacteria by breaking down the cell walls.”
“Sticky mucus.”
“Expel bacteria: body attempts to dilute or purge bacteria from the body.”
describe the proteins (cytokines, interferons, interleukins, complement) and cells (natural killers, phagocytes) that make up the second line of defense
The second line of defense is activated when pathogens breach surface barriers.
Proteins:
Cytokines: Signaling molecules that enhance immune responses; produced by various cells.
Interferons: Released by virus-infected cells; interfere with viral replication by degrading viral DNA.
Interleukins: Made by white blood cells (leukocytes); regulate immune responses among leukocytes.
Complement proteins: Help destroy pathogens; activate through two pathways:
Classical: Requires antibodies to bind to the pathogen first.
Alternative: Doesn’t require antibodies; triggered directly by pathogen surfaces.
Cells:
Natural Killer (NK) cells: Patrol the body for abnormal cells; kill infected or cancerous cells.
Phagocytes:
Macrophages: Mature from monocytes; engulf and digest pathogens.
Neutrophils: Abundant WBCs; become phagocytic on contact with pathogens.
Eosinophils: Target parasites and are active in allergic reactions.
Basophils: Release histamine (vasodilation) and heparin (anticoagulant).
Word-for-Word Notes
“Cytokines: proteins that enhance the immune response.”
“Interferons: ‘dying words’ from an infected cell, degrades viral DNA & stops replication.”
“Interleukens: made by leukocytes and affect leukocytes.”
“Complement: aids destruction of antigens (helps adaptive and innate complete their job).”
“Natural Killers: ‘policing cells’ that work before adaptive enacted.”
“Phagocytes: Macrophages… Neutrophils… Eosinophils… Basophils: histamines (vasodilates), heparin (anticoagulant).”
describe the role of inflammation and fever in the second line of defense and explain the steps involved in inflammation (vasodilation, and phagocyte mobilization
Inflammation:
A localized response to injury or infection.
Functions:
Stops the spread of pathogens.
Removes damaged cells and pathogens.
Starts tissue repair.
Steps of Inflammation:
Vasodilation: Increases blood flow and vessel permeability to bring immune cells and proteins to the site.
Phagocyte Mobilization:
Damaged cells release chemical signals that attract leukocytes (WBCs).
Neutrophils are the first responders; they bind to adhesion molecules on vessel walls.
They squeeze through vessel walls (diapedesis) to reach the site and begin cleanup.
Fever:
A systemic response triggered by pyrogens that reset the hypothalamus.
Increases body temperature to inhibit microbial growth and enhance immune efficiency.
Word-for-Word Notes
“Inflammation: Helps to activate and mobilize WBCs to area of damage.”
“Prevents spread of damaging event… gets rid of cellular debris & pathogens… begins tissue repair.”
“Steps: Vasodilation: mobilizes defenses… Phagocyte mobilization.”
“Neutrophils bind to damaged endothelial cells… flatten and squeeze in between blood vessel endothelial cells.”
“Fever: abnormally high body temperatures, b/c hypothalamic thermostat is reset.”
compare and contrast the cells of adaptive immunity (B cells and T cells) including the type of immunity, where the cells are produced, where the cells mature, location of the antigen, and any sub-type of cell produced
B Cells:
Type of immunity: Humoral (antibody-mediated).
Produced in: Red bone marrow.
Mature in: Red bone marrow.
Target antigens: Free-floating antigens in body fluids.
Subtypes:
Plasma cells: Produce antibodies.
Memory B cells: Retain memory for faster future responses.
T Cells:
Type of immunity: Cellular (cell-mediated).
Produced in: Red bone marrow.
Mature in: Thymus.
Target antigens: Antigens displayed on infected cells.
Subtypes:
CD4 (Helper T cells): Activate other immune cells.
CD8 (Cytotoxic T cells): Kill infected cells directly.
Memory T cells: Enable faster responses upon re-exposure.
Word-for-Word Notes
“B Cells… Type of immunity… Where cells are produced… mature… antigen… sub-type (or cells produced).”
“T helper cells/CD4 cells help to activate the cytotoxic T cells.”
“Cytotoxic cells/CD8 will destroy infected body cells.”
“MHC proteins… Antigens are processed and presented on the MHCs.”
describe what exogenous and endogenous in relation to the location of the antigen
Exogenous Antigens:
Originate from outside the body’s cells.
Found in extracellular fluids.
Taken up by phagocytosis and presented by MHC class II molecules.
Examples: bacteria, toxins, allergens.
Endogenous Antigens:
Originate from within the body’s own cells.
Usually produced when a cell is infected (e.g., by viruses).
Presented by MHC class I molecules.
Examples: viral proteins made inside an infected cell, tumor antigens.
Word-for-Word Notes
“Antigens: non-self, usually a protein.”
“Endogenous: originates inside your body cell.”
“Exogenous: originates outside the cell and taken into cell by phagocytosis.”
describe the steps involved (binding to antigen, clonal selection, formation of memory cells, function of cells) in the activation of T helper cells (CD4), T cytotoxic cells (CD8) and B cells (plasma cells)
T Helper Cells (CD4):
Bind to antigens presented on MHC class II of antigen-presenting cells (APCs).
Undergo clonal selection—proliferate into active and memory T helper cells.
Active T helpers stimulate B cells and cytotoxic T cells.
T Cytotoxic Cells (CD8):
Bind to antigens on MHC class I.
Also undergo clonal selection.
Active cytotoxic cells kill infected body cells.
Memory cytotoxic T cells remain for future encounters.
B Cells:
Recognize free antigens in body fluids.
Upon activation, they clone themselves.
Differentiate into:
Plasma cells: secrete antibodies.
Memory B cells: remain dormant until future exposures.
Word-for-Word Notes
“Activation of Cell Mediated Immunity: CD4 (T helper cells)… Bind to antigen, Clonal selection, Memory cells and active cells.”
“CD8 (T cytotoxic)… Bind to antigen, Clonal selection, Memory cells and active cells.”
“Activation of B cells: Clonal selection. Plasma cells: antibody secreting cells. Memory cells: inactive storage.”
“Antibodies Produced… Neutralization, Agglutination, Precipitation, Complement, Enhance phagocytosis.”
“Memory cells remain for decades.”
Note 
Flashcards (37)