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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
- The perimetrium (serosa) is the outermost layer
- The myometrium is the middle layer, consisting of three layers of smooth muscle (thickest)
- 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
- Menstrual
- Preovulatory
- Ovulation
- 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
- Endocrine cells of the pancreatic islets: a. Secrete insulin, glucagon, somatostatin, and pancreatic polypeptide into bloodstream
- 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
