Homeostasis Flashcards
excretory system
serves many function, including the regulation of blood pressure, blood osmolarity, acid-base balance, and removal of nitrogenous wastes
Kidney
Filters blood and produces urine.
nephron
detrusor muscle
Muscle in bladder that contracts under parasympathetic tone.
internal urethral sphincter
Made of smooth muscle and contracted in its normal state.
external urethral sphincter
Consists of skeletal muscle and is under voluntary control.
Micturation reflex
Stretch receptors in bladder ⇒ CNS ⇒ Parasympathetic neurons ⇒ detrusor muscle contraction/internal sphincter relaxation
- voluntary contraction of external sphincter causes urination
Secretion
Movement of salts, acids, bases, and urea directly into tubule by active or passive transport.
Reabsorption
Compounds that are filtered or secreted are taken back up for use. Glucose, amino acids, and vitamins are always reabsorbed. ADH inserts AQP to increase amount of water reabsorbed.
Proximal Convoluted Tubule
reabsorbed: amino acids, glucose, water-soluble vitamins, salts, water
Secreted: hydrogen ions, potassium ions, ammonia and urea.
Found in renal cortex
Loop of Henle
Descending limb: permeable to only water
Ascending limb: permeable to only salts (creates gradient for water to move out of descending limb
Distal convoluted tubule
Reabsorbed: sodium (aldosterone) and water
Secreted: wastes
Collecting Duct
Water reabsorption due to ADH and aldosterone. “point of no return.”
Aldosterone
Release by adrenal cortex in response to decreased blood pressure.
ADH
Peptide hormone synthesized by the hypothalamus and released by the posterior pituitary in response to high blood osmolarity.
Bicarbonate buffer system
If blood pH is low, increased respiratory rate and excretion of hydrogen ions/absorption of bicarbonate
If blood pH is high, decreased respiratory rate and excretion of bicarbonate/absorption of hydrogen ions.
Skin
Protects from exposure to the elements and invasion by pathogens.
Layers: Epidermis, Dermis, Hypodermis
Epidermis
Stratified Squamous epithelium (keratinocytes)
Melanocytes: produce melanin and pass it on to keratinocytes
Come Let’s Get Sun Burned
Dermis
Sweat glands, blood vessels, and hair follicles originate in the dermis. Most sensory receptors are also located in the dermis i.e. meissner’s corpuscles, ruffini endings, and pacinian corpuscles
Hypodermis
Connects skin to the rest of the body. Contains fat, fibrous tissues, and large vessels.
Thermoregulation
Hot conditions: sweating and arteriolar vasodilation
Cold conditions: adipose insulation, piloerection, superficial arteriole constriction, and shivering
