Urinary system

what is micturition? what are the muscles involved with it?

- it is urination. the act of emptying the urinary bladder. -Muscles involved with urination: *detrusor muscle*: smooth muscle in the bladder, when it contracts it forces urine out of the bladder. *internal urethral sphincter*: smooth muscle that is normally contracted when the bladder filled with urine. *external urethral sphincter*: skeletal muscle around the urethra at the opening that control the timing or urination.

What are the symptoms of diabetes mellitus?

-*hyperglycemia*: normal amount of glucose is 80 mg % (80 mg of glucose/ 100 mL of H2O). -*glucosuria*: glucose in urine. normally there is 0% glucose in urine. -*polyuria*: urinate a lot. increase H2O in urine. Typically dehydrated. -*fatigue*: abnormally tired. less glucose goes into cells for fuel.

What is the transport maximum? what is the tmax for glucose?

-it is the maximum amount of a substance (mg) that can be reabsorbed out of the renal tube in one minute (mg/min). -320 mg/minute

What is facultative reabsorption controlled by?

-its controlled by hormones, ADH and ALDO.

What are the parts of the renal tubule?

-proximal convoluted tubule: site of most reabsorption and secretion. -Loop of Henle: U shaped loop of the renal tubule associated with ADH-regulated water absorption. -distal convoluted tubule: site of reabsorption and secretion.

what is the renal pelvis? what are calyces?

-renal pelvis is found within the kidney. urine collects in the pelvis before it drains into the ureter. -there are major and minor calyces. that are branches off the renal pelvis that receive urine from the collecting ducts and drains into the pelvis.

What does Diabetes mellitus mean? What are the types of diabetes?

-translates to "sweet tasting urine", meaning there are excess amounts of glucose in the urine, when there should be none at all. - Type 1 diabetes: insulin dependent. INS increases the synthesis of GLUT. Type 2: not insulin dependent. down-regulates the INS receptors on target cells.

What regulates ALDO?

1. RAAS: (renin angiotensin aldosterone system) helps maintain blood volume. -angiotensin 2 helps to simulate the release of ALDo from the adrenal gland. 2. Higher than normal [K+] in the blood will stimulate the release of ALDO. high levels of K+ can lead to arrythmia.

What are the components of the juxtaglomerular apparatus?

1. granular cells: are enlarged smooth muscle cells in the wall of afferent arteriole. they secrete renin, which involved in Na+ reabsorption. 2. macula densa: tubular epithelial cells in the walls of the DCT in contact with the granular cells of afferent arteriole. the cells of the macula densa detect increases in the salt concentrations of the DCT.

What are the components of the urinary system?? what doe they do?

1. kidneys: filter blood plasma of water products to make urine. 2. ureters: tubes that drain the urine from kidney to urinary bladder. 3. urinary bladder: storage for urine 4. urethra: drains urine from the urinary bladder to outside of the body.

how does ADH help regulate reabsorption? Where is ADH secreted from? what are its target cells?

ADH- anti-diuretic hormone. -ADH will decrease the volume of urine made by the kidneys. -Its secreted from the posterior pituitary gland. -its target cells are epithelial cells within the collecting duct

Describe glomerular filtration

Filtration occurs as the blood pressure forces plasma through the filtration barrier and into the capsular space within the GC. About 20% of the blood plasma gets filtered. -The filtrate from the PCt onward is called the tubular fluid.

how does renin help regulate blood pressure?

If BP drops, it stimulates granular cells to secrete *renin* into the blood. Renin is an enzyme. -renin converts angiotensinogen to *angiotensin 1.* -As ANG1 circulates through capillaries in lungs, it is acted upon by the enzyme *ACE*. ACE converts ANG1 to *angiotensin 2*. -ANG2 is a vasoconstrictor that increases PR, therefore increasing BP.

what is a nephron? how many per kidney?

It is the functional unit of the kidney that filters blood to make urine. about 1.2 million per kidney.

Describe the process of releasing ADH starting with normal levels of H2O in the blood.

Normal [H2O]---> dehydration--> negative H2O balance: hypertonic plasma---> stimulate osmoreceptors in the hypothalamus---> release ADH from posterior pituitary--> increase the number of the AQP in the plasma membranes of CD cells.

What does filtrate not contain?

RBC, WBC, platelets, plasma proteins

what are NKCC transporters? where are they found?

Transport 4 ions: Na+, K+ and 2 Cl-. -found in cuboidal epithelial cells that line the thick limb of the ascending branch.

What is the juxtaglomerular apparatus?

a system that regulates the rate of filtrate formation and systemic blood pressure. -helps control glomerular filtration rate.

How can glucose being osmotically active in the renal tubule affect dehydration?

because it will decrease the strength of the osmotic gradient for H2O reabsorption. -it results in less H2O being reabsorbed back into the body.

Why is the BP so high at the GC?

because the afferent arteriole is larger than the efferent arteriole. This pressure it what forces the plasma through the semipermeable membrane of the GC.

describe tubular reabsorption. what gets reabsorbed?

chemicals in the filtrate that are needed are moved out of the renal tube and into peritubular capillaries (PTC). -all glucose, amino acids, most water, and salt ions get reabsorbed.

What does filtrate contain?

contains salts, glucose, amino acids, vitamins, and water, nitrogen containing waste products

Describe the ascending branch of the loop of Henle. what is it impermeable and permeable to?

impermeable to H2O and permeable to salt ions.

Describe the descending branch of the loop of henle. what is it impermeable and permeable to?

it is permeable to H2O, but impermeable to salt.

What is the renal corpuscle? its components?

it is the site of filtration. it is made up by the Glomerulus (network of capillaries) and the glomerular capsule(surrounds the glomerulus.

How does ALDO? where is it secreted from?

its steroid hormone secreted from the cortex of the adrenal gland. it is important for the reabsorption of water and salt reabsorption and K+ secretion. -Takes effect in the DCT and CD.

Where is angiotensinogen produced?

liver

What is renal threshold? what is the renal threshold for glucose?

the amount of glucose (in mg) in 100 mL of plasma at which glucose first appears in the urine. Or when the Tmax for glucose is exceeded. The renal threshold for glucose os 180mg/ 100mL plasma.

what are the peritubular capillaries?

tiny blood vessels that travel alongside nephrons allowing reabsorption and secretion between blood and the inner lumen of the nephron.

describe secretion. what gets secreted?

waste products in the PTC that escaped glomerular filtration are moves out of capillaries and into renal tubule. -excess H+, K+, and NH3.

How does ALDO help with secretion?

when levels of K+ ge too high in the blood, ALDO will increase the secretion of K+ into the urine.

what is the micturition?

when the bladder reaches 300-400 mL, it will stretch the walls of the bladder, this will stimulate stretch receptors to send signal into sacral segments of the spinal cord. -the lateral horns of the spinal cord will then stimulate parasympathetic neurons, which release ACh. -ACh will stimulate detrusor muscle to contract. it will also stimulate the internal urethral sphincter. Both together will cause a person to urinate unless the person is contracting the external urethral sphincter.