lecture 28 objectives Flashcards
Explain the relationship between changes in alveolar ventilation (i.e., hypoventilation and hyperventilation), arterial blood PCO2, arterial blood pH, and arterial blood HCO3-.
o Hypoventilation refers to a decrease in alveolar ventilation, leading to an increase in arterial PCO2 (carbon dioxide pressure). The increase in CO2 will combine with water to form carbonic acid, which dissociates into H+ (hydrogen ions) and HCO3- (bicarbonate ions), causing the pH of the blood to decrease (acidosis).
o Hyperventilation involves an increase in ventilation, leading to a decrease in arterial PCO2. With less CO2 in the blood, the pH increases (alkalosis) because there are fewer hydrogen ions in the blood.
o Arterial blood bicarbonate (HCO3-) changes in response to respiratory changes but is typically slower to adjust. In the case of hypoventilation, the kidneys will attempt to compensate by retaining HCO3- to buffer the excess hydrogen ions. In hyperventilation, the kidneys may compensate by excreting bicarbonate.
Explain the mechanisms by which the nephron secretes or retains filtered bicarbonate ions/makes new bicarbonate ions.
o The nephron helps maintain acid-base balance through processes in the proximal convoluted tubule and distal convoluted tubule.
o In acidotic conditions, the kidneys will secrete H+ into the filtrate and reabsorb HCO3- back into the blood, thereby restoring the bicarbonate buffer system.
o In alkalotic conditions, the kidneys will excrete excess HCO3- in the urine, helping to lower the pH.
o The nephron can also produce new bicarbonate by buffering secreted hydrogen ions through the formation of ammonia (NH3), which can combine with H+ to form ammonium (NH4+), thus allowing bicarbonate to be synthesized and reabsorbed into the blood.
Define acidosis and alkalosis.
o Acidosis is a condition where the pH of the blood drops below 7.35, indicating an excess of H+ ions (acidic conditions).
o Alkalosis is a condition where the pH of the blood rises above 7.45, indicating an excess of HCO3- ions or a deficiency in H+ ions (basic conditions).
Compare and contrast metabolic and respiratory causes of pH imbalances.
o Respiratory acidosis/alkalosis results from changes in PCO2, which affects the CO2 content in the blood. Respiratory acidosis occurs due to hypoventilation (high CO2, low pH), while respiratory alkalosis occurs due to hyperventilation (low CO2, high pH).
o Metabolic acidosis/alkalosis is caused by changes in bicarbonate (HCO3-) levels. Metabolic acidosis can result from increased production of acids (e.g., diabetic ketoacidosis) or loss of bicarbonate (e.g., diarrhea). Metabolic alkalosis typically results from excessive loss of H+ (e.g., vomiting) or excessive intake of bicarbonate.
define the concept of compensation
Compensation refers to the body’s efforts to restore normal pH levels when disrupted. The lungs and kidneys are the main organs involved in compensation
the relation to disruption of pH homeostasis
In respiratory acidosis, the kidneys increase bicarbonate reabsorption and hydrogen ion secretion to raise pH.
In both respiratory acidosis and alkalosis, the kidneys help compensate by regulating bicarbonate levels and hydrogen ion secretion. In acidosis, the kidneys try to increase the excretion of acids, primarily as ammonia (NH4+), and reabsorb more bicarbonate, which helps neutralize the excess acid. In alkalosis, the kidneys compensate by increasing the excretion of bicarbonate and decreasing the secretion of hydrogen ions
In metabolic acidosis, the lungs increase ventilation to expel CO2, lowering PCO2 and increasing pH.
In metabolic alkalosis, the kidneys will excrete excess bicarbonate, while the lungs may decrease ventilation to retain CO2 and lower pH.
Given arterial blood values for PCO2, pH and HCO3-, determine whether a patient is in acidosis or alkalosis and whether the cause of the pH disturbance is metabolic or respiratory.
o If pH is low (below 7.35), the patient is in acidosis; if pH is high (above 7.45), the patient is in alkalosis.
Respiratory causes can be identified if PCO2 is abnormal and the change in PCO2 correlates with the pH disturbance.
Metabolic causes are identified if HCO3- is abnormal, and compensation is seen in the opposite system (lungs or kidneys).
examples in changes in pH
- For example:
o Low pH, high PCO2 indicates respiratory acidosis (hypoventilation).
o Low pH, low HCO3- indicates metabolic acidosis (e.g., diabetic ketoacidosis, renal failure).
Compare and contrast the major anatomy of the testicular and ovarian systems.
o Testes: Male gonads that produce sperm and testosterone. They are located in the scrotum outside the body, which maintains an optimal temperature for sperm production.
o Ovaries: Female gonads that produce eggs (ova) and hormones like estrogen and progesterone. They are located in the pelvic cavity and are part of the menstrual cycle.
Describe how sex is determined beyond just “XX” vs “XY” genotypes
o While the presence of XX or XY chromosomes determines biological sex, other genetic and hormonal factors play a role in sexual differentiation. For example, the SRY gene on the Y chromosome leads to the formation of the testes, while the absence of this gene in females leads to the formation of ovaries.
Define intersex and give an example of an intersex condition.
o Intersex refers to a variety of conditions where individuals are born with ambiguous genitalia or characteristics that do not fit typical definitions of male or female. An example of an intersex condition is Androgen Insensitivity Syndrome (AIS), where individuals with an XY genotype develop female external genitalia due to the inability of cells to respond to androgens.
Identify homologues of various testicular/ovarian system structures (e.g., ovary is homologous to the testis).
o Testes are homologous to ovaries.
o Penis is homologous to the clitoris.
o Scrotum is homologous to the labia majora.
o Vas deferens is homologous to the fallopian tubes in that both transport reproductive cells.
Identify and describe the gross anatomy, microscopic anatomy, and functions of the testes.
o Testes are made up of seminiferous tubules, where sperm production occurs. These tubules are surrounded by interstitial cells (Leydig cells), which produce testosterone.
Identify and describe the structure and functions of the spermatic cord and testicular system ducts (e.g., ductus [vas] deferens, ejaculatory duct, urethra).
o The spermatic cord contains blood vessels, nerves, and the vas deferens, which carries sperm to the ejaculatory duct.
Identify and describe the structure and functions of accessory glands (i.e., seminal glands [seminal vesicles], prostate gland).
o The seminal vesicles and prostate gland contribute to semen, providing nutrients and enzymes to support sperm viability and motility.
o Semen is composed of sperm and secretions from accessory glands
Identify and describe the structure and functions of the testicular system external genitalia (e.g., scrotum, penis).
o Testes are homologous to ovaries.
o Penis is homologous to the clitoris.
o Scrotum is homologous to the labia majora.
o Vas deferens is homologous to the fallopian tubes in that both transport reproductive cells.
Describe the pathway of sperm from the seminiferous tubules to the external urethral orifice of the penis.
o Seminiferous tubules -> rete testis -> efferent ductules -> epididymis - >Vas deferens (ductus deferens) - > ejaculatory duct -> urethra -> external urethral orifice
describe the production of semen
o Production - Semen is produced primarily in the reproductive glands that surround the male reproductive system. The main components are sperm and fluids secreted by the following glands:
Seminiferous tubules in the testes (sperm production).
Seminal vesicles (fluid secretion).
Prostate gland (fluid secretion).
Bulbourethral glands (pre-ejaculatory fluid).
describe the composition of semen
The composition of semen includes sperm cells and seminal plasma (the fluid portion).
Sperm cells
Seminal plasma
describe the functions of semen
Transport of sperm
Nourishment and protection of sperm
Enhancing sperm motility
Aiding in fertilization
Neutralization of female tract acidity
define spermatogenesis
is the process by which sperm is produced, starting with spermatogonia and developing into mature spermatozoa
define spermiogenesis
the final maturation of sperm.
Describe the stages of spermatogenesis in the seminiferous tubule, including the roles of the nurse (sustentacular, Sertoli) cells and interstitial cells (of Leydig).
o Spermatogenesis in the seminiferous tubules involves several stages, including mitosis and meiosis, and is supported by Sertoli cells and Leydig cells. Sertoli cells provide a nurturing environment and regulate spermatogenesis, while Leydig cells produce testosterone, essential for the process
Describe endocrine regulation of spermatogenesis. (e.g., gonadotropin releasing hormone [GnRH], follicle stimulating hormone [FSH], luteinizing hormone [LH], androgens, inhibin).
o Endocrine regulation involves GnRH from the hypothalamus stimulating the release of FSH (follicle-stimulating hormone) and LH (luteinizing hormone) from the anterior pituitary. FSH stimulates Sertoli cells to support spermatogenesis, while LH stimulates Leydig cells to produce testosterone.
