excretory system Flashcards
– medial side
- where renal artery and nerve enter kidney
- where renal vein, ureter, lymphatic vessels exit kidney
- opens into the renal sinus
hilum
contains blood vessels
-part of the system for collecting urine and adipose tissue
renal sinus
– cone-shaped
-tip project toward the center
Renal Pyramids
surrounds tip of renal pyramid
-calyces join to form renal pelvis
Calyx –
functional unit of each kidney
-approx. 1.3 M for each kidney
nephron
enlarged end of nephron, double-walled chamber
bowman’s capsul
tuft of capillaries (ball of yarn)
glomerulus
carry fluid from cortex through medulla
Collecting ducts –
– (15%) have loops of Henle that extend deep into the medulla
Juxtamedullary nephrons
(85%) loops of Henle do not extend deep into the medulla
Cortical nephrons –
parts of filtration membrane
Endothelium of glomerular capillaries
Podocytes
Basement membrane
Structures consisting of Simple cuboidal epithelium
Proximal convoluted tubules
Thick segments of Loop of Henle
Collecting ducts
consists of microvilli and mitochondria that actively transport ion & molecules across the wall of nephron
Simple Cuboidal epithelium –
Structures consisting of Simple Squamous
Thin segments of the descending and ascending loop of henle
– formed when the distal convoluted tubule come in contact with afferent arteriole
-certain cells secrete renin
Juxtaglomerular apparatus
movement of water, ions and small molecules through filtration membrane into Bowman’s capsule
A.FILTRATION –
portion of plasma entering the nephron
-formation depends on filtration pressure (pressure gradient)
Filtrate -
– blood pressure in the glomerular capillary
Glomerular capillary pressure
– pressure of the filtrate already inside Bowman
Capsular Pressure
– pressure within glomerular capillary
-Because most plasma proteins do not pass the filtration membrane, they produce an osmotic pressure that favors fluid movement into the glomerular capillary from Bowman’s capsule
Colloid Osmotic Pressure
– allows small solutes and water to readily pass but not blood cells and most proteins except for albumin
-thus filtrate contains no cells and little protein (albumin)
Filtration membrane
– movement of substances from filtrate across nephron wall back into the blood of peritubular capillaries
TUBULAR REABSORPTION
active transport of solutes across nephron walls into the filtrate
-can either be active or passive
C. TUBULAR SECRETION –
– secreted by cells of juxtaglomerular apparatuses in kidneys
- acts on angiotensinogen to convert it into angiotensin I
- angiotensin-converting enzyme converts angiotensin I into angiotensin II
renin
– acts on the adrenal cortex, causing it to secrete aldosterone
angiotensin II
– increases rate of active transport of Na in distal convoluted tubules and collecting ducts
Aldosterone
– secreted by posterior pituitary gland
- passes through circulatory system to the kidneys
- regulates amount of water reabsorbed by the distal convoluted tubules and collecting ducts
- release is regulated by hypothalamus
- also influenced by baroreceptors (monitor BP) ↓BP, ↑ADH secretion
ADH
– secreted from cardiac muscle cells in the right atrium of the heart
C. ATRIAL NATRIURETIC HORMONE
– small tubes that carry urine from renal pelvis of kidney to posterior inferior portion of urinary bladder
-transitional epithelium
Ureters
hollow, muscular container in the pelvic cavity posterior to pubic symphysis
-stores urine, thus its size depends on the quantity of urine present
ub
– tube that carries urine from urinary bladder to the outside of the body
- extends to the end of penis in males
- female urethra: shorter and opens into the vestibule
Urethra
– triangle-shaped portion of the urinarybladder located between the opening of the ureters and opening of urethra
Trigone
contracts to keep semen from entering the UB during sexual intercourse
Internal urinary sphincter –
– made of skeletal muscle that surrounds urethra as the urethra extends through the pelvic floor
- under voluntary control
- normally contracted as a result of stimulation somatic nervous system
External urinary sphincter
activated by stretch of the urinary bladder wall
- ↑urine volume in UB, ↑pressure, baroreceptors stimulated, AP conducted along parasympathetic nerves, UB contracts
- an automatic reflex, but could be inhibited or stimulated by higher brain centers
MICTURITION REFLEX-
– includes fluid inside all cells of the body
- enclosed by cell membranes of individual cells
- composition of fluid in all compartment and regulation of fluid movement are similar
- hold 2/3 of all the water in the body
INTRACELLULAR FLUID COMPARTMENT
– all the fluid outside the cells • Interstitial fluid • Plasma within BV • Fluid in lymphatic vessels -has 1/3 of the total body water
EXTRACELLULAR FLUID COMPARTMENT
– contain fluid with composition different from other extracellular fluid
Subcompartments
fluid in subcompartments
- Aqueous humor
- Vitreous humor
- CSF
- Synovial fluid
- Serous fluid
- Fluid secreted by glands
- Renal filtrate
- Bladder urine
- Interstitial fluid
- Plasma within BV
- Fluid in lymphatic vessels
compartment with ↑conc of ions such as K, Mg, PO4, SO4
- lower conc of Na, Ca, Cl, HCO3
- more protein than ECF
intracellular
– major influence controlling the movement of water between intra and extracellular space
Osmosis
*Total amount of water and ions in the body long termdoes not change unless individual is
growing, gaining or losing weight
– the thirst center, controls water intake
hypothalamus
Body fluid ph:
7.35 – 7.45
chemicals that resist change in the ph of a solution when either acids or bases are added to the solution
buffer
- Proteins
- PO43- buffer system
- HCO3- buffer system
3 Major Buffers in Body Fluids:
powerful regulator of ph, but it responds more slowly than does the respiratory system
-cells in the walls of DCT are primarily responsible for H+ secretion
KIDNEYS-
occurs when blood ph falls below 7.35
ACIDOSIS –
– when respiratory system is unable to eliminate adequate amounts of carbon dioxide
Respiratory acidosis
excess production of acidic substances such as lactic acid and ketone bodies
-caused by increased metabolism or decreased ability or urine to eliminate H in the urine
• Metabolic acidosis –
– occurs when blood ph increases above 7.45
- major effect: hyperexcitability of nervous system
- spasms and tetanic contractions, extreme nervousness, convulsions
ALKALOSIS
alkalosis resulting from hyperventilation
respiratory alkalosis
alkalosis caused by rapid elimination of H from body (during severe vomiting or excess aldosterone secretion)
• Metabolic alkalosis –
