Human Physiology Flashcards

Flashcards for reviewing human physiology, focusing on fluid and electrolyte balance.

What is the role of the Kidney in fluid and electrolyte homeostasis?

The primary route for excreting ions and water.

What is Diuresis?

Removing excess water in plasma, excreting it as urine.

What allows water to be reabsorbed and urine to be concentrated in the kidney?

High osmolarity in the ECF.

What is the function of the Ascending Limb in urine concentration?

The ascending limb is impermeable to water and actively transports Na+ out of the tubule into the ECF, creating a high osmolarity in the ECF.

What does the Descending Limb lose by osmosis into the ECF?

Water

What is the role of the Vasa recta in countercurrent exchange?

Blood in the vasa recta removes water leaving the loop of Henle.

How does the Vasa Recta contribute to water reabsorption and maintain the osmolarity of the medullary interstitium?

Vasa Recta absorbs ions into blood, increasing in osmolarity, then Vasa Recta absorbs water from Descending Limb, and dilute blood is directed away from medullary interstitium

Where is ADH produced and released from?

Hypothalamus (produced) and Posterior Pituitary (stored/released)

What is the effect of ADH on the collecting duct and DCT?

The collecting duct and DCT become more permeable to water allowing for water reabsorption.

Describe the Signal Transduction Pathway of ADH

ADH binds to receptor on Basolateral membrane of Tubule cells resulting in exocytosis of Vesicles containing Aquaporins which insert into Apical Membrane creating water pores allowing Osmosis of water from filtrate, through Tubule cells and into ECF

What are the 3 stimuli for ADH release?

Plasma Osmolarity, Blood Volume, and Blood Pressure

What type of hormone is Aldosterone?

Steroid hormone, so receptor is in ICF of target cell. Genomic effect

Which hormones and glands directly and indirectly stimulates release of Aldosterone?

Adrenal Cortex Directly by ACTH from Anterior Pituitary and indirectly by CRH from Hypothalamus, but primarily via RAAS

What is the Signal Transduction Pathway for Aldosterone?

Aldosterone combines with a cytoplasmic receptor resulting in transcription in the nucleus and translation and protein synthesis makes new protein channels and pumps and increased Na+ reabsorption and K+ secretion.

What are the direct effects of Aldosterone in terms of Na+ and K+?

Na+ Reabsorption and K+ Secretion

What does aldosterone cause in terms of sodium reabsorption?

Increase Osmolarity in ECF and Peritubular Capillaries

What are the 3 stimuli for Aldosterone release?

Hyperkalemia, Hyponatremia, and Low blood pressure (via RAAS)

How does Angiotensin II increases blood pressure?

Increases Aldosterone production, Increases ADH production, Stimulates thirst, Vasoconstriction, and Increased Cardiac Output

From where are Natriuretic Peptides produced?

Produced by Atria; Natriuresis causes Diuresis

Naturesis Peptides are antagonistic to which hormone?

Aldosterone because Aldosterone increases Na+ reabsorption

What are the effects of Dehydration?

Increased Osmolarity in ECF, Decreased blood volume, and Decreased blood pressure

Which hormones are released to resume Homeostasis?

ADH and Angiotensin

What happens to Neurons during Acidosis?

Neurons become less excitable; CNS depression; Protein denaturation.

What happens to Neurons during Alkalosis?

Neurons become hyperexcitable; severe can lead to muscle tetanus

What is the biggest source of acid in the body?

CO2

What regulates blood pH?

Plasma Proteins (esp Albumin), Phosphate ions, Bicarbonate, Ventilation, and Renal System

How can the body attempt to compensate/return to Homeostasis?

Renal: Secrete H+ Reabsorb Bicarbonate

How can the body attempt to compensate/return to homeostasis?

Respiratory system can increase ventilation to expel CO2 and Renal system will secrete H+ and reabsorb Bicarbonate

How can the body attempt to compensate/return to Homeostasis?

Renal system: increase reabsorption of H+ stop secretion of H+

How can the body attempt to compensate/return to homeostasis?

Respiratory system decrease ventilation and Renal increase reabsorption of H+