Ch. 10: Homeostasis Flashcards
what organs comprise the excretory system
kidneys, ureters, bladder, urethra
where is the cortex located inside the kidney
the outer layer
where is the medulla located inside the kidney
the inner layer
where is the renal pelvis
center of the medial surface of the kidney, widest aspect of the ureter which to connects the renal hilum
what is the flow of blood in the kidney
renal artery –> afferent arterioles –> glomeruli –> efferent arterioles
what are the vasa recta
the secondary capillary beds surrounding the loop of Henle
what is a portal system
two capillary beds in series through which blood must travel before returning to the heart
detrusor muscle location
muscle that lines the bladder and causes the internal urethral sphincter to contract under parasympathetic control
what is the micturition reflex
stretch of bladder muscles –> detrusor muscle contraction –> internal sphincter relaxes
what is the primary job of the kidneys (big picture)
regulate blood volume and osmolarity through filtration, secretion, and reabsorption
keep what the body needs, lose what it doesn’t, concentrate urine in order to save water
what is the filtrate
the fluid pulled from the blood, through the glomerulus, into the Bowman’s space by starling forces
how does the glomerulus filter the blood into filtrate
by size, blood is filtered through glomerular pores
what is secretion
process in which solute is move from the blood into the filtrate anywhere outside of bowman’s capsule (usually in the nephrons)
ex: liver filters ammonia to produce urea, which travels in the blood to the nephron and is secreted into the filtrate
what kids of substances are secreted
substances in excess concentration in the blood that are too large to pass through the glomerular pores
what is reabsorption
process in which some compounds that have been filtered are reabsorbed back into the blood
ex: glucose, vitamins
What are the major waste products excreted in the urine
H+, urea, NH3, K+
Dump the HUNK
what occurs in the proximal convoluted tubule (PCT)
- filtrate enters here first
- solutes (Na+, CL-, H2O) and water are reabsorbed
- waste products are secreted
- solute is isotonic
what is the descending limb of the loop of Henle permeable to
water only
what occurs to the filtrate as it travels through the descending limb of the loop of Henle
- interstitum becomes more salty as the limb descends further into the medulla
- the filtrate becomes hypotonic relative to its surroundings
- the filtrate becomes more concentrated as water flows down the concentration gradient
what occurs in the countercurrent multiplier system
- flow of filtrate through loop of Henle is opposite in direction from blood in vasa recta
- filtrate is constantly exposed to hypertonic blood to maximize water reabsorption
what is the ascending limb of the loop of Henle permeable to
salts only
what occurs to the filtrate as it travels through the ascending limb of the loop of Henle
- intertial fluid becomes less salty
- FIRST Na+ and Cl- passively flow to hypotonic surroundings
- SECOND Na+ and Cl- are actively transported to hypertonic surroundings
what is the net change in the filtrate after passing though the entirety of the loop of Henle
- filtrate is slightly dilute in comparison to blood
- volume of filtrate significantly reduced
what occurs in the distal convoluted tubule
- NaCl is transported out of the filtrate
- Water follows the flow of NaCl from the filtrate
- Waste products are secreted into filtrate
what hormone acts on the DCT
aldosterone
what hormones act on the collecting duct
aldosterone and ADH/vasopressin
what occurs in the collecting duct
filtrates last pass through the nephron where final concentration of urine is determined, permeability to water/salt depends on hormone control
how does aldosterone work (big picture)
- steroid hormone (long onset, long lasting)
- secreted by adrenal cortex in response to decreased blood pressure
- increases DCT and collecting duct’s ability to reabsorb Na+
- as Na+ is reabsorbed, H2O is reabsorbed, and BP increases
pathway of aldosterone release
low BP –> renin released from juxtaglomerular cells –> renin cleaves angiotensinogen, forming angiotensin I –> angiotensin-converting enzyme converts AGI –> AGII –> aldosterone is released from the adrenal cortex
what will be excreted when aldosterone is released
increased levels of K+ and H+
how does ADH/vasopressin work (big picture)
- peptide hormone (fast onset, short-term affects)
- released by posterior pituitary in response to high blood osmolarity
- increases permeability of collecting duct to water and making cell junctions leaky
- H2O is reabsorbed
skin layers from inside out
hypodermis (subcutaneous), dermis, and epidermis
from what germ layer is the skin derived from
the ectoderm
what does the stratum basale do
- stem cells
- produces keratinocytes which produce keratin
where is the stratum lucid found
thick, hairless, skin (soles of feet and palms)
layers of skin from superficial to deep
Come, Let’s Get Sun Burned
corneum, lucidum, granulosum, spinosum, basale
how do calluses form
keratin is deposited in excess due to repeated strain of friction
what does melanin do
- produced by melanocytes in the basal layer
- pigment that protects DNA from UV radiation
- melanocytes increase in production in response to UV radiation (tan)
what do the Lanerhans cells do
- macrophages in the spinosum
- present antigens to t-cells to activate the immune sytem
where are most sensory receptors located
the dermis
- Merkel cells (deep pressure)
- Meissner’s corpuscles (light touch)
- Ruffini endings (stretch)
- Pacinian corpuscles (deep pressure and vibration)
