urinary system Flashcards
what are the major components of the urinary system & what are their primary functions?
2 kidneys: (8 primary functions)
1. regulation of blood ionic composition
2. regulation of blood pH
3. regulation of blood volume
4. regulation of blood pressure (through the secretion of renin)
5. maintenance of blood osmolarity
6. production of hormones (namely calcitriol and erythropoietin)
7. regulation of blood glucose level
8. excretion of wastes and foreign substances
2 ureters: paired tubes that transport urine from the kidneys to the urinary bladder
1 urinary bladder: a temporary storage reservoir for urine
1 urethra: a tube that carries urine from the bladder to the body exterior
what is the location of the kidneys?
· Located above the waist and attached to the posterior wall of the abdomen (retroperitoneal).
· They are positioned between the levels of the last thoracic and the third lumbar vertebrae.
· They are partially protected by the eleventh and twelfth pairs of ribs.
· The right kidney is slightly lower than the left becuase of the presence of the liver on the right side
Near the center of the kidney’s concave medial border is a depression called the _____ _____, through which travel:
renal hilum:
- ureter
- blood vessels and lymphatic vessels
- nerves
what are the three layers of supportive tissue that surround each kidney (from superficial to deep)?
- renal fascia (superficial layer) - anchors the kidney and adrenal gland to surrounding structures and to the abdominal wall
- adipose capsule - (mass of fatty tissue) which protects the kidney from trauma and holds it in place
- renal capsule (deep layer) - smooth transparent sheet of dense irregular connective tissue which maintains the shape of the kidney and prevents infections in surrounding regions from spreading to the kidney
the functional portion of the kidney’s tissue is called ______.
the parenchyma
what are the two layers of the parenchyma?
- an outer layer called the renal cortex
- an inner region called the renal medulla
the renal medulla contains 8-18 cone-shaped _____ _____, whose apexes are called _____ _____
renal pyramids, renal papillae
what is the name of the portions of the renal cortex that extend between renal pyramids?
renal columns
what makes up a renal lobe?
a renal pyramid, its overlying area of renal cortex, and half of each adjacent renal column
what are the functional units of the kidney’s parenchyma that filters blood, returns useful substances to blood, and removes unwanted substances from the blood, thereby producing urine?
nephrons
what is the pathway in which urine flows once it is produced by nephrons?
· urine from the nephrons drains into the papillary dicts and onwards into minor calyces, which merge from major calyces, which deliver the urine into a large cavity called the renal pelvis
· urine then exits the kidney by flowing into a uterer
blood flows through the kidneys via the following sequence:
- the right and left renal arteries supply the kidneys
- they branch into segmental arteries, which branch into interlobar arteries
- the interlobar arteries arch between the renal medulla and cortex, and are referred to as arcuate arteries here.
- afferent arteriole branches come off the interlobar arteries and supply each nephron
- the afferent arteriole divides into a ball of capillaries called a glomerulus
- the glomerular capillaries reunite to form the efferent arteriole
- the efferent arteriole divides to form the peritubular capillaries
- these reunite to form peritubular venules, then interlobar veins and eventually the renal vein.
renal nerves are part of the _____ division of the autonomic nervous system
sympathetic
a nephron consists of what two portions?
- the renal corpuscle, where plasma is filtered
- the renal tubule, into which the filtered fluid passes
what are the two components of the renal corpuscle?
- glomerulus: a capillary network (recieves blood from afferent arterioles & drains blood into efferent arterioles)
- glomerular (bowman’s) capsule: a double walled epithelial cup that surrounds the glomerular capillaries; this is where blood plasma is filtered before being passed into the renal tubule
as filtered fluid travels through the renal tubule, it passes through these three segments:
- proximal convoluted tubule (PCT)
- loop of henle (nephron loop)
- distal convoluted tubule (DCT)
distal convoluted tubules of several nephrons empty into a single _____ _____.
collecting duct
collecting ducts merge to form what kind of ducts?
papillary ducts (which drain into a minor calyx)
which kind of nephron consists of about 80-85% of all nephrons and usually has its glomerulus in the outer part of the cortex, and its short loop of henle penetrating into the outer region of the medulla?
cortical nephron
which kind of nephron consists of about 15-20% of all nephrons and usually has its glomerulus deep in the cortex, and its long loop of henle penetrating deep into the medulla?
juxtamedullary nephron
which kind of nephron has a thin ascending limb followed by a thick ascending limb and permits the excretion of very dilute to very concentrated urine?
juxtamedullary nephron
what are the three major processes involved in urine formation?
- glomerular filtration: water and most solutes in blood plasma move across the wall of glomerular capillaries into the glomerular capsule and into the renal tubule
- tubular reabsorption: tubule cells reabsorb about 99% of the filtered water and many useful solutes into the peritubular capillaries and vasa recta (reabsorption refers to the return of substances to the bloodstream)
- tubular secretion: tubule cells and collecting duct cells secrete wastes, drugs, and excess ions into the fluid as it moves through the tubule and collecting duct (secretion here means removing substances from blood)
* excreted substances remain in the urine and subsequently leave the body *
pores in the glomerular epithelial cells that cause them to be quite leaky are called ______. what is their role?
fenestrations - permits filtration of water and small solutes but prevents filtration of most plasma protein, blood cells & platelets