A&P Final PDF

Urinary system Functions of the Urinary System: - Excretion of waste - Regulation of blood volume and blood pressure - Regulation of plasma ions - Regulation of extracellular fluid pH - Regulation of nutrients and vitamin D synthesis - Regulation of erythrocyte produc...

Urinary system Functions of the Urinary System: - Excretion of waste - Regulation of blood volume and blood pressure - Regulation of plasma ions - Regulation of extracellular fluid pH - Regulation of nutrients and vitamin D synthesis - Regulation of erythrocyte production= EPO production The Nephron Functional unit of kidney- forms urine Consist of: o Renal Corpuscle- 2 parts ▪ Bowman's capsule ▪ Glomerulus- porous capillary o Renal Tubule ▪ PCT ▪ Loop of Henle-Descending and ascending limb ▪ DCT Filtration Vasculature - Vessel that brings blood to the glomerulus- Afferent arterial - Blood is filtered across the filtration membrane - Blood exits the glomerulus through the – Efferent arterial Urine formation 1. Filtration- inside the renal corpuscle 2. Reabsorption- in the PCT 3. Secretion- in DCT Proce of glomerular filtration Anatomy of the filtration membrane o Glomerular endothelium o Fenestrated o Basement membrane Physiology of Filtration o Force promoting filtration  ▪ Glomerular capillary pressure~50mmg o Opposing force ▪ Colloid osmotic pressure- due to albumins ~30mmg ▪ Capsular pressure~10mmg Small molecules are filtered, and large ones are Not filtered List examples of filterable molecules o Water o Ions (K+, NA+, CL-) o Nutrients (glucose and amino acids) o Wastes (urea, urine, creatine) List what is too large to filter o Blood cells o Plasma proteins Process of tubular reabsorption How is the PCT modified for reabsorption? o Brush border (microvilli) increase surface area Transport mechanisms: o Na+ is an active transport. Sodium potassium pump o Cl-, opposite attract- follows the electrochemical gradient of NA, passive o Glucose, facilitated diffusion (passive) and cotransport with sodium (active) o Water, by osmosis Some molecules have a transport maximum Fixed number of carrier proteins for reabsorption of- glucose and amino acids When the number of glucose molecules exceeds the number of carrier proteins- glucose appears in the urine Increased urine production: diuresis Osmotic diuresis- increased water loss from excess solutes in urine. Summary of important aspects of tubular reabsorption Sodium drives reabsorption of solutes and water Hydrogen ions are secreted when sodium is reabsorbed- counter transport Active and passive transport processes move substances into the PCT cells and the peritubular capillaries Loop diuretics cause les water to be reabsorbed along the nephron loop and increase urine volume Proces of tubular secretion Some molecules secretion directed by hormones o K ions- aldosterone from adrenal cortex cause K+ secretion. Na+ is reabsorbed o Na/K ATPase pump ▪ Active transport- ATP is needed Substances secreted by active transport: o Hydrogen ions ▪ To balance pH o Potassium ions ▪ Main way we lose potassium is urination o Drugs ▪ To prevent toxic buildup Secretion is reabsorbed in reverse- things move from the blood into the DCT Regulation of urine concentration and volume Renin-angiotensin-aldosterone mechanism Hormone mechanism o Also tied to renin mechanism o Antidiuretic hormone o Atrial natriuretic hormone ▪ Also called ANP The JG apparatus stimulates renin-angiotensin-aldosterone mechanism Stimulus+ low BP or low glomerular filtration rate o Normal GFR~125mL/min Release of renin by afferent arteriole - Renin-angiotensin-aldosterone mechanism causes an overall increase in water reabsorption leading to: Increased blood volume Increased blood pressure Other factors can affect urine production  Caffeine o Inhibits sodium and other ion reabsorption o Increases urine volume/output Alcohol o Inhibits release of ADH Blood/colloid osmotic pressure o Dehydration o Albumin, Na+, other solutes What effect do the hormones ADH and ANH have on urine output? - ADH effect urine output by decreasing it - ANH effect on urine output by increasing it, natural diuretic Micturition is controlled by the parasympathetic nervous system Micturition reflects steps 1. Stretch receptors in urinary bladder signal parasympathetic neurons 2. Parasympathetic neurons in sacral region of spinal cord cause contractions of detrusor muscle 3. External urethra sphincter relaxes, then internal urethral sphincter relaxes.... urination begins 4. When urine volume exceeds 500 mL, the increased pressure forces the internal sphincter open followed by external Composition of urine 95% water Nitrogen waste o From amino acid catabolism- urea o From muscle metabolism- creatinine o From nucleic acid catabolism- uric acid Abnormal components of urine Glycosuria- glucose Ketonuria-ketones Albuminuria- protein Bilirubinuria- bile pigments Pyuria- white blood cells Hematuria- red blood cells Dialysis- diffusion of waster products across dialysis membrane Fluid and electrolyte balance control hormones that target the kidney tubules Water functions Body temperature regulation Protection Lubricant o Mouth o Joints Chemical reactant o Aerobic and anerobic Solvents o Electrolytes Transport o Lymphatic o Cardiovascular Fluid compartments ICF- intracellular fluid ECF- extracellular fluid Osmolarity and fluids shifts tend to involve Na+ - Hypertonic- higher solute concentration, water follows - Hypotonic- lower solute concentrations Water moves to where there is more solute, and water follows salt Water balance is tied to electrolyte balance Fluid shifts Water gains Water loss Hormonal control Important electrolytes Sodium o Regulation of sodium concentration- alderstone o Major functions-pH and fluid balance  Potassium o Regulation of potassium concentrations- alderstone o Major functions- excitable membrane Calcium o Regulation of calcium contractions- PTH o Major functions All three function in muscle contraction, nerve impulse conduction, and heart action. Acid-Base balance is important to homeostasis PH scale o Measure of H+ concentration in a solution o Ranges from 0 (acidic) to 13 (alkaline) Acids o Release hydrogen ions in solution Bases o Release hydroxide ion o Hydrogen ion acceptors Normal blood pH range- 7.35 to7.45 3 mechanisms in the body that maintain homeostasis of pH Chemical buffers o Protein buffers o Carbonic acid-bicarbonate buffer system o Instant acting, present in all body fluids o Ex. Hemoglobin inside RBC Respiratory compensation o Fast acting Renal compensation o Slow acting o Kidneys balance how much hydrogen and bicarbonate Respiratory system can affect pH balance by altering breathing rate Increase PCO2 increase H+ and decrease pH Decrease PCO2 decreased H+ and increase pH Blood pH under 7.35- acidosis Blood pH over 7.45- alkalosis Caused of alkalosis Excess blood bicarbonate o Excessive consumption of antiacids Loss of blood acids o Vomiting from stomach Loss of carbon dioxide from blood o Hyperventilation Cause of acidosis Overproduction of acids o Ketoacidosis (starvation, low carb diet) o Excess lactic acid production Excessive loss of basses o Prolonged diarrhea Buildup carbon dioxide The kidneys also contribute to pH regulation Renal compensation- takes 3-5 days to kick in H+ secreted Bicarbonate reabsorbed The Reproduction System Meiosis - Haploid N=23, 4 daughter cells crossing over independent homologous pairs - Prophase 1- crossing over - Anaphase 1- separate homologous pairs - Telophase 1 –haploid N=23 Meiosis 11 - Separation of sister chromatids - Four new cells Male Reproductive organs: Testes  Location o Dartos muscles- smooth muscle of scrotum - Spermatic cord o Cremaster muscle- pulls testes closer to body - Descent of the testes and cryptorchidism o Cryptos= hidden o Orchitic= concerning the testicles - Must be surgically corrected- sperm need lower body temp to be viable Anatomy of Testes - Tunica albuginea o White fibrous tissues- covers testes - Seminiferous tubules o Spermatogenesis- sperm formation o Interstitial cells- found outside seminiferous tubule and produces testosterone o Nurse cells- nourish developing spermatocytes - Rete testes o Maze-like tubules where seminiferous tubules combine as they leave testis Anatomy of Spermatozoan Head o Acrosomal cap- to penetrate zona pellucida o Nucleus- DNA here - Midpiece(body) o Mitochondria and ATP production- use fructose to make ATP o Tial-flagellum - Capacitation- sperm become active, motive and fully functional; requires contact with: o Seminal vesical secretion o Female reproduction tract secretions Meiosis and spermatogenesis Cells in the seminiferous tubule 1. Spermatogonia- stem cells that undergo mitosis 2. Primary spermatocyte- 2N=46=diploid, divide meiosis 1 3. Secondary spermatocyte- N=46=haploid, divide meiosis 2 4. Spermatid- N=23 and spermiogenesis-physical changes  5. Spermatozoa (sperm) N=23 6. Nurse cells- blood-testis barrier- prevents immune system from attacking sperm cell Spermatozoan ductile system - Seminiferous tubules collect at the rete testis - Epididymis: 23 feet long o Takes 2 weeks for sperm to travel through it o Function- physical maturation, chemicals here prevent premature capacitation - Ductus/vase deferens o Straight, muscular tube - Ejaculatory duct - Urethra o Prostatic urethra o Membranous urethra o Spongy urethra 3 kinds of male accessory glands that produce seminal fluid Seminal glands o Alkaline secretion o Fructose and ATP to power flagellum o Prostaglandins-contracts smooth muscle Prostate o Acidic secretion o Seminal plasmin o Prostatic hypertrophy Bulbourethral glands o Thick, alkaline mucus o Neutralize acids o Lubricates glans Hormones of the male GnRH from hypothalamus o Secretion begins at puberty FSH and LH from anterior pituitary o Targets gonads  Testosterone from interstitial cells o Stimulated by LH Inhibin from sustentacular cells o Stimulated by FSH o Inhibits FSH production as inhibin builds up o Negative feedback Testosterone levels are regulated through negative feedback - High testosterone levels inhibit release of GnRH from hypothalamus - Reduces LH levels from anterior pituitary - Testosterone levels drop Function of testosterone - Maturation of sperm - Maintains accessory organs - Secondary sex characteristics o Body hair o Enlargement of larynx o Thickening of vocal cords o Thickening of skin o Increase muscle mass o Growth spurts at puberty Female reproductive anatomy - Ovaries (gonads) o Descend from near kidneys during development o Ligaments o Ovarian- attaches to ovary to uterus The oocyte develops inside a follicle Outer cortex o Primordial follicles o At birth, about 300,00 to 400,000 o Primary oocyte undergoes meiosis 1 o Developing follicles- primary, secondary, tertiary Inner medulla o CT, blood vessels, lymphatic and nerves Stages of follicular development 1. Primordial follicle a. Single layer squamous cells surround oocyte 2. Primary follicle a. One more layer of cuboidal cells, no antrum 3. Secondary follicle a. Antrum appears 4. Mature follicle a. Undergoes ovulation- release of secondary oocyte enters oviduct 5. Corpus luteum a. Temporary endocrine organ b. Remains in implantation occurs 6. Scar of carpus luteum Meiosis and oogenesis Primary oocyte (2N=46) o starts meiosis 1, stuck in prophase 1. Completes meiosis 1 just before ovulation Secondary oocyte (N=23) + polar body o Divides by meiosis 2- stuck in metaphase 2-completes meiosis 2 only if fertilization occurs Ovum-mature egg o Present only until nuclei of ovum and sperm fuse Polar bodies o Non-viable eggs cells Zygote (2N=46) o Goes through mitosis o Ovum and spermatozoan= zygote Follicles mature due to FSH, and they produce hormones FSH (follicular stimulating hormone) o Produced by anterior pituitary o Stimulate follicle growth Follicle cells o Secondary and mature follicles make estrogens primarily Graafian follicle o Undergoes ovulation and pushes secondary oocyte out of ovary Hormones of the female reproductive system Hypothalamus o GnRH-stimulates release of FSH+LH Anterior pituitary o FSH- stimulates follicular growth-estrogen production o LH- stimulates development of corpus luteum- progestin production- quiets uterus Ovaries o Estrogen o Progesterone The ovarian cycle 1. Follicular phase a. FSH dominant- follicle growth and development and spike in LH, stimulates ovulation 2. Ovulation a. Estrogen rise as follicle growth 3. Luteal phase a. LH dominant- LH promotes development of corpus luteum-progestins Uterine cycle 1. Manses a. Caused by drop in progesterone and estrogen 2. Proliferative phase a. Estrogen stimulates buildup of endometrium 3. Secretory phase a. Progesterone stimulates development of glands and blood vessels of endometrium Functions of estrogen Bone and muscle growth Female secondary sex characteristics Sex drive Accessory reproductive organs Buildup of endometrial cells Aging and reproductive changes  Menopause o Ovaries unresponsive to FSH and LH o Decreased estrogen levels Andropause o Male climacteric o Decline in testosterone production- more gradual than0 menopause