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Human Embryology, Inheritance, and Reproductive Systems Review, Study Guides, Projects, Research of Biology

A comprehensive review of human embryology, inheritance, and reproductive systems. It covers topics such as the embryonic period, gastrulation, the formation of the amnion and yolk sac, the development of the heart, and the karyotype. It also delves into inheritance, including incomplete dominance and x-linked inheritance. The document further explores the male and female reproductive systems, including the structure and function of the testes, scrotum, epididymis, seminiferous tubules, ductus deferens, seminal vesicle, ejaculatory duct, prostate, and bulbourethral glands. It also discusses the female reproductive cycle, the female reproductive system, and the phases of the female reproductive cycle. Additionally, it covers acid-base balance, the urinary system, homeostatic kidney functions, the nephron, glomerular filtration, reabsorption and secretion in the proximal convoluted tubule, the loop of henle, and the liver and gallbladder.

Typology: Study Guides, Projects, Research

2023/2024

Available from 04/15/2024

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BIOS-256 Final Exam Review
Embryonic Period
oThe embryonic period extends from fertilization through the 8th week of development
Fertilization is:
merging of genetic information from haploid sperm and
haploid secondary oocyte
oFraternal twins:
Results from two eggs developing in the uterus at the same time, each of
which is fertilized by its own sperm
oIdentical twins:
Results from one fertilized egg (ovum) splits and develops into two babies
with the same genetic information
oThe haploid nucleus in the head of the sperm becomes the male pronucleus
oThe haploid nucleus of the fertilized ovum becomes the female pronucleus
- When the two merges (syngamy), it results in the diploid zygote
Embryonic Period- Week 1 Summary
Embryonic Period- Week 2
oThe amnion forms from the roof the amniotic cavity
Eventually, it surrounds the entire embryo and fills with amniotic fluid
oOn the 8th day, the exocoelomic membrane forms, which, together with the
hypoblast, forms the yolk sak
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BIOS-256 Final Exam Review

  • Embryonic Period o The embryonic period extends from fertilization through the 8th week of development ▪ Fertilization is: - merging of genetic information from haploid sperm and haploid secondary oocyte o Fraternal twins: ▪ Results from two eggs developing in the uterus at the same time, each of which is fertilized by its own sperm o Identical twins: ▪ Results from one fertilized egg (ovum) splits and develops into two babies with the same genetic information o The haploid nucleus in the head of the sperm becomes the male pronucleus o The haploid nucleus of the fertilized ovum becomes the female pronucleus - When the two merges (syngamy), it results in the diploid zygote
  • Embryonic Period- Week 1 Summary
  • Embryonic Period- Week 2 o The amnion forms from the roof the amniotic cavity ▪ Eventually, it surrounds the entire embryo and fills with amniotic fluid o On the 8 th^ day, the exocoelomic membrane forms, which, together with the hypoblast, forms the  yolk sak
  • Embryonic Period- Week 3 and 4 o The first major event of the 3 rd^ week of development is  gastrulation ▪ The two-layered embryonic disc transforms into a trilaminar (three- layered) embryonic disc (ectoderm, mesoderm, endoderm) o On day 18 and 19 ▪ The heart begins to develop in the head and of the embryo in a region of mesodermal cells called the cardiogenic area o At about 4 weeks after fertilization, ▪ The head end of the neural tube develops into three enlarged areas called primary brain vesicles
  • Embryonic Period- Day 52 o By the end of the 8 th^ week, ▪ Eyelids come together, the tail disappears, external genitals being to differentiate, and digits are distinct and are no longer webbed o The fetal period begins at the 9 th^ week after fertilization ▪ Tissues and organs that developed during the embryonic period grow and differentiate

o Most patterns of inheritance don’t conform to the simple dominant recessive inheritance pattern o Incomplete dominance: a situation where neither member of the pair of alleles is dominant over the other o An example of incomplete dominance is the inheritance of sickle cell anemia

  • Inheritance- Karyotypes o The 46 human chromosomes (23) pairs are identified by their size, shape, and staining pattern o A karyotype  an entire set of chromosomes arranged in decreasing size order and according to the position of the centromere
  • Inheritance X-Linked Inheritance o The 23 pairs of human chromosomes include 22 pairs of autosomes and one pair of sex chromosomes (X and Y) ▪ Males have an X and a Y chromosome ▪ Females have two X chromosomes (one is automatically inactivated) - Whether the sperm that fertilizes an egg carries an X or x Y chromosome determines the gender of the zygote o Sex-linked traits are non-sexual traits that are inherited on the X chromosome
  • Reproductive System o Testes: ▪ Paired, oval glands in the scrotum partially covered by the tunica vaginalis o Scrotum ▪ A sac of loose skin and underlying subcutaneous tissues that contains the testes

o Epididymis: ▪ Store’s sperm and transports it from the testes o Seminiferous tubules ▪ Carry sperm produced within theme (spermatogenesis) out of the testes o Ductus Deferens (Vas deferens) ▪ Carries sperm from the epididymis to the ejaculatory duct o Seminal vesicle ▪ Secrete an alkaline, viscous fluid containing fructose, prostaglandins, and clotting proteins o Ejaculatory Duct ▪ Delivers sperm into the urethra, adding secretions and additives from the prostate necessary for sperm function o Prostate ▪ A single, donut-shaped gland that secretes a milky, slightly acidic fluid containing citric acid, proteolytic enzymes, acid phosphatase, and seminal plasmin o Bulbourethral (Cowper’s) glands ▪ Secrete an alkaline fluid during sexual arousal that neutralizes acids from urine and mucus for lubrication

  • Male reproductive system and spermatogenesis

o Hormones control testicular function ▪ At puberty gonadotropin releasing hormone (GnRH) ▪ Stimulates cells in the anterior pituitary gland to produce luteinizing hormone (LH) and follicle stimulating hormone (FSH) o LH  stimulates cells in the testes (interstitial cells) to produce testosterone o FSH  stimulates spermatogenesis

  • There is a system of ducts in the male reproductive system o Sperm and fluid travel from the seminiferous tubules to straight tubules and then to a network of ducts, the rete testis o Efferent ducts  carry the sperm to the epididymis o Sperm mature in the epididymis and degenerated sperm are reabsorbed o The epididymis propels sperm into the ductus (vas) deferens o The ductus (vas) deferens exits the tails of the epididymis and ascends through the spermatic cord into the pelvis o Then, it loops over the ureter and passes over the side and down the posterior surface of the urinary bladder
  • Female reproductive system o Ovaries: ▪ Paired glands homologous to the testes. They produced gametes (mature into ova) and hormones (progesterone, estrogens, inhibin, relaxin) ▪ They are supported by the broad ligament, ovarian ligament, and suspensory ligament o Fallopian tube: ▪ Transport male sperm cells to the egg, provide a suitable environment for fertilization, and transport the egg from the ovary

o Vagina: ▪ Sexual intercourse, childbirth, and menstruation o The uterus is part of the pathway for sperm deposited in the vagina to reach the uterine tube and where a fertilized ovum will implant o Histologically, there are three layers to the uterus

  1. The perimetrium (serosa) is the outermost layer
  2. The myometrium is the middle layer, consisting of three layers of smooth muscle (thickest)
  3. The endometrium is the inner layer a. Its stratum functionalis layer is shed each month during menstruation o The vulva (pudendum) refers to the external genitalia of the female o The vulva includes: ▪ Mons Pubis: ▪ Source of cushioning during sexual intercourse
  • The mons pubis also contains sebaceous glands that secrete pheromones to induce sexual attraction ▪ Labia Minora: ▪ Protective structures that surround the clitoris, urinary orifice, and vaginal orifice ▪ Labia Majora: ▪ Contains sweat and sebaceous glands, which produce lubricating secretions ▪ Clitoris: ▪ Equivalent to male’s penis ▪ Vestibule (hymen, vaginal orifice, external urethral orifice, openings of cuts of several glands) o Paraurethral (skene’s) glands ▪ Secrete mucus and are embedded in the wall of the urethra ▪ They are homologous to the prostate o Greater Vestibular (Bartholin’s) glands ▪ Produce mucus during sexual arousal to provide lubrication ▪ They are homologous to the bulbourethral gland
  • Female Reproductive System o The mammary glands are in each of the two breasts and are modified sudoriferous glands that produce milk ▪ Mammary glands contain 15-30 lobes - Each lobe has lobules containing milk secreting glands called alveoli ▪ Each breast has a nipple containing lactiferous ducts where milk emerges - The skin around the nipple is the areola Label  suspensory ligament, areola, mammary duct
    • The female reproductive cycle o Non pregnant females experience cyclical changes in the ovaries and uterus lasting approximately one month ▪ The cycle involves oogenesis and preparation by the uterus to receive a fertilized ovum o The ovarian cycle ▪ Includes changes that occur during and after maturation of the oocyte o The uterine cycle ▪ Involved changes in the endometrium that prepare it for implantation of the developing embryo
  • The female reproductive cycle o Phases of the female reproductive cycle: ▪ the cycle generally ranges from 24-36 days
  1. Menstrual
  2. Preovulatory
  3. Ovulation
  4. Postovulatory
  • Fluid, Electrolytes, and acid base balance

o The major hormone that regulates the water loss is ▪ ADH  Antidiuretic hormone

  • Acid-Base balance o The pH of arterial blood ranges from ▪ 7.35-7. o Mechanisms that maintain this range: ▪ Buffer systems ▪ Exhalation of carbon dioxide o Hemoglobin in red blood cells acts as a buffer: ▪ Carbonic acid-bicarbonate buffer system ▪ Based on the - Bicarbonate ion (HCO3-)  acts as a weak base - Carbonic acid (H2CO3)  acts as a weak acid o Exhalation of carbon dioxide: ▪ Exhaling CO2 leads to  rise in pH ▪ Retaining CO2 leads to  drop in pH o Kidney excretion of H+: ▪ Excreting H+ in the urine removes nonvolatile acids ▪ What secretes H??? - distal convoluted tubule and collecting ducts of the kidneys
  • Acid-Base imbalances o Acidosis: ▪ blood pH is below 7. o Alkalosis: ▪ blood pH is above 7. o Respiratory Acidosis: ▪ blood pH drops due to excessive retention of CO2 leading to excess H2CO o Respiratory Alkalosis: ▪ blood pH rises due to excessive loss of CO2 as in hyperventilation o Metabolic Acidosis: ▪ Arterial blood levels of HCO3- falls o Metabolic Alkalosis: ▪ Arterial blood levels of HCO3- rises
  • The urinary system o Kidneys  form urine o Ureters  transport urine from kidneys to bladder o Bladder  store urine o Urethra  excrete urine from bladder to outside of body
  • Homeostatic kidney functions o Regulation of blood ionic composition ▪ Na+, K+, Cl- o Regulation of blood pH ▪ H+, HCO3-

o Regulation of blood volume ▪ H2O o Regulation of blood pressure o Maintenance of blood osmolarity o Production of hormones ▪ Calcitriol and Erythropoietin o Excretion of metabolic wastes and foreign substances (drugs or toxins) o Regulation of blood glucose level

  • The Nephron
  • The renal corpuscle o The glomerulus o Glomerular capsule (bowman’s capsule)
  • Cortical vs Juxtamedullary nephrons o Create urine with osmolarity like blood o Enable kidney to secret very concentrated urine
  • Glomerular Filtration o Glomerular filtration rate (GFR)  amount of filtrate formed by both kidneys each minute o Angiotensin II  constricts afferents and efferent arterioles, decreasing GFR o Atrial natriuretic peptide (ANP)  relaxes mesangial cells, increasing capillary surface area ad GFR ▪ ANP is secreted in response to stretch of the cardiac atria
  • Reabsorption and secretion in PCT o All nutrients, such as glucose and amino acids, are reabsorbed o 65% of Na+ and water reabsorbed
  • Mechanical and chemical digestion in the mouth o Mechanical digestion ▪ Chewing mixes food with saliva and forms a bolus which can be easily swallowed o Chemical digestion ▪ Salivary amylase converts polysaccharides to disaccharides ▪ Lingual Lipase
  • Gastric Pits
    • The Pancreas o The pancreas:

▪ Produces enzymes that digest carbohydrates, proteins, fats, and nucleic acids ▪ Produces sodium bicarbonate which buffers stomach acid ▪ Empties its contents into the duodenum

  • Two functions of the pancreas
    1. Endocrine cells of the pancreatic islets: a. Secrete insulin, glucagon, somatostatin, and pancreatic polypeptide into bloodstream
    2. Exocrine cells: a. Acinar cells and epithelial cells of duct system secrete pancreatic juice o Pancreatic alpha-amylase o Pancreatic lipase o Proteolytic enzymes o Nucleases
  • Liver and gallbladder o Liver makes  bile ▪ Important in the emulsification of fats o The gallbladder stores bile until it is needed
  • Functions of the liver and gallbladder o Carbohydrate, lipid, and protein metabolism o Processing of drugs and hormones o Bilirubin excretion o Bile salt synthesis o Storage- glycogen o Phagocytosis o Vitamin D activation
  • Small Intestine o Majority of digestion and absorption occur in the small intestine

o Regulation of metabolism  depends on chemicals in the cells and signals from the nervous and endocrine system ▪ During the absorptive state, (insulin)

  • Glucose is readily available ▪ During the postabsorptive state, (glucagon)
  • Energy needs are met by fuels already in the body