AnP Chapter 19 (LO3) Flashcards
Kidneys
the principal organs of the urinary system
Blood filters through kidneys and they remove potential poisons, adjust the water content of blood, tweak levels of sodium and potassium, and adjust the pH level
Play a role in regulation of blood pressure in the production of red blood cells
Overview of the urinary system
The urinary system consist of the kidneys, ureter’s, urinary bladder and urethra
4 organ systems perform excretory processes:
Respiratory system: excrete carbon dioxide and water
The integumentary system: excretes water, electrolytes, lactic acid, and urea through sweat
The digestive system: excrete water, carbon dioxide, lipids, bile pigments and other metabolic wastes
The urinary system: excretes metabolic wastes, drugs, hormones, salts and water
Hilum
a slit in which Structures enter and leave the kidney through it
Located in a concave notch on the medial side
The interior of the kidney consist of two regions
the renal cortex in the renal medulla
Renal cortex
the site of urine production and forms the outer region of the kidney
Renal medulla
the sign of urine collection and forms the inner region
Renal columns
Extensions from the renal cortex that divide the interior region into cone shaped sections
Renal pyramids
the cone shaped sections consist of tubules for transporting year and away from the cortex the base of each pyramid faces outward toward the cortex
Renal papilla
the point of the pyramid that faces the hilum
Minor calyx
a cup the renal popular extends into that collects urine leaving the papilla
Major calyx
2 or 3 minor calyces joined together
Renal pelvis
receives urine from the major calyces and continues to the ureter
Ureter
a tube like structure that channels urine to the urinary bladder
Renal artery
branches off the abdominal aorta and brings blood to the Kidney
divides branching into smaller arteries which pass through the renal columns and extend into the renal cortex
Renal vein
the way in which blood leaves the kidney and gets emptied into the inferior vena cava
Nephrons
the filtration units of the kidney the primary lie in the kidneys outer region
Each nephron is well supplied with blood
how renal circulation works
- In the cortex a series of afferent arterials arise from the smaller arteries each supplies blood to one nephron
- Glomerulus: cluster of capillaries that each afferent arteriole branched into
- –Enclosed by bowmans capsule - Blood leaves the glomerulus through and efferent arteriole
- Peritubular capillaries: a network of capillaries around the renal tubes that efferent arterial’s lead to
- –These could pillories pick up water and solutes reabsorbed by the renal tubules - Blood flows from the pear tubular capillaries into larger and larger veins that eventually feed into the renal vein
Nephron
Microscopic functional units of the kidney
Consist of two main components of renal corpuscle and renal tubule
Renal corpuscle
filters blood plasma
The beginning of the nephron
Consists of a glomerulus and bowman’s capsule
Fluid filters out the glomerulus and collects in the space between the two layers of Bowmans capsule
From there it flows into the proximal renal tubule on the other side of the capsule
Renal tubule
where urine is formed
A series of tube like structures that lead away from the glomerulus
Can be divided into four regions the proximal convoluted tubule, nephron loop, distal convoluted tubule, and collecting duct
Bowman’s capsule
consists of two layers of epithelial cells that envelop the glomerulus in an Open ended covering
how renal tubules work
- Arising directly from bowmans capsule is the Proximal convoluted tubule
- –Proximal convoluted tubule: a winding, convoluted portion of the renal tube - Loop of Henle: The renal tube straightens out and dips into the medulla before turning sharply and returning to the cortex
- –Consists of a descending limb in ascending limb - After returning to the cortex the ascending limb coils again forming the distal convoluted tubule
- The collecting duct: receives drainage from the distal convoluted tubule’s of several different nephrons
- –Passes into a renal pyramid where it merges with another collecting duct to form one tube that opens at Arena poplar into a minor calyx
Urine formation
The creation of urine by nephrons involves 3 processes: glomerular filtration, tubular reabsorption and tubular secretion
3 components of Glomerular filtration
- Blood flows into the glomerulus through the afferent arterial which is much larger than efferent arterial meaning blood flows in faster than it can leave which contributes to higher pressure within glomerular capillaries
- The walls of glomerular capillaries are dotted with pores allowing water and small solutes to filter out the blood and into the Bowmans capsule
- –Blood cells and most plasma proteins are too large to pass through the pores - The fluid that has filtered into the Bowmans capsule flows into the renal tubes
- –Glomerular filtration rate (GFR): the amount of fluid filtered by both kidneys
- –Equals about 180 L each day the body reabsorbs about 99% leaving 1 to 2 L to be excreted as urine
Proteinurina
the presence of protein in the urine
Regulations of the glomerular filtration rate
If the flow rate is too high the body will lose excessive amounts of water and nutrients if it’s too low the tubules may re-absorb toxins that should be secreted
Specialize cells in the distal convoluted tubule monitor the flow rate and composition of filtrate allowing the renal tubes to make adjustments to alter flow as needed
Renin-angiotensin aldosterone system
a key mechanism for maintaining blood pressure and study glomerular filtration rate
How the glomerular filtration rate works
- A drop in blood pressure leads to decreased blood flow to the kidneys
2 Renin: converts inactive plasma protein angiotensinogen into angiotensin I.
- Angiotensinogen I circulates to the lungs where angiotensin-converting enzyme (ACE) converts it into angiotensin II
- Angiotensin II stimulates the adrenal glands to secrete aldosterone
- Aldosterone causes the distal convoluted tubule to retain sodium, which leads to increased retention of water
- –Blood volume increases and blood pressure rises
Juxtaglomerular cells
specialized cells found in the afferent arterioles that respond by releasing the enzyme renin
Tubular reabsorption
additional chemicals removed from the filtrate and returned to the blood
Tubular secretion
chemicals are added
Most of the water, electrolytes and nutrients are reabsorbed in the proximal convoluted tubule’s by active and passive transport
- Sodium moves by active transport out of the proximal convoluted tubule and into the blood stream of the peritubular capillaries
- –Water flows sodium diffusing rapidly from tubular fluid into the blood along with glucose, amino acids, chloride, potassium and bicarbonate
- —Simultaneously waste such as ammonia and uric acid as well as drugs are secreted out of the blood into the tubules - Water diffuses out of the descending limb of the loop of Henle further concentrating the filtrate
- Sodium and chloride are actively pumped out of the ascending limb of the loop of Henle into interstitial fluid before passing into surrounding a pillories
- The distal convoluted tubule and collecting ducts reabsorb variable amounts of water and salt
- –Specialize cells play a role in acid balance base reabsorbing potassium and secreting hydrogen into the tubule - The collecting duct reabsorbs water and concentrates the filtrate resulting in urine
hormone: Aldosterone
- actions
- effects on kidney
- Effects on blood volume and pressure
action
- When blood levels of sodium fall or when the concentration of potassium rises the adrenal cortex secretes aldosterone which promotes the distal convoluted tubule to absorb more sodium and secrete more potassium
Effects on kidney
- Reabsorbs sodium chloride and water
- Excretes potassium
Effects on blood volume and pressure
- Increase blood volume
- Increase blood pressure
hormone: Atrial naturietic peptide (ANP)
- actions
- effects on kidney
- Effects on blood volume and pressure
action
- When blood pressure rises the atrium of the heart secretes a NP which inhibits the secretion of aldosterone and antidiuretic hormone
effects on kidney
- Excretes sodium chloride and water
Effects on blood volume and pressure
- Decreased blood volume
- Decrease blood pressure
hormone: Antidiuretic hormone (ADH)
- actions
- effects on kidney
- Effects on blood volume and pressure
actions
- Secreted by the posterior pituitary gland it causes the cells of the collecting duct to become more permeable to water
effects on kidney
- Reabsorbs water
Effects on blood volume and pressure
- Blood volume increases
- Blood pressure increases
hormone: Parathyroid hormone (PTH)
- actions
- effects on kidney
- Effects on blood volume and pressure
actions
- Secreted by the parathyroid glands in response to low blood calcium levels
effects on kidney
- Reabsorbs calcium
- Excretes phosphate
Effects on blood volume and pressure
- No effect on blood volume or pressure
diuretics
- Commonly administered to increase your volume
- Increased urine volume leads to decreased blood volume and blood pressure
Ureters
slender muscular tubes that connect the renal pelvis of each kidney with the bladder
Urinary bladder
Collapsible muscular sac that sits behind the symphysis pubis and below the peritoneal membrane
Mucus transitional epithelium lines the bladder
Detrusor muscle
the wall of the bladder consists of three layers of smooth muscle
Rugae
folds of tissue when the bladder is relaxed
As you’re in first bladder the rugae flatten in the epithelium thins allowing the bladder to expand
The floor of the bladder has three openings
two from the ureters and one from the urethra which form a triangular shape
Trigone
a smooth area on the floor of the bladder
Infections commonly attack this area
Internal urethral sphincter
a ring of smooth muscle that contracts involuntarily to retain urine in the bladder
External urinary sphincter
exits where the urethra passes through the pelvic floor
Consists of skeletal muscle and is under voluntary control
Urethra
small tube that conveys urine away from the bladder and out of the body
External urinary meatus
opening of the urethra leading to the outside of the body
Urethra structure
Female : And women in the youth is 3 cm long and exits the body just in front of the vaginal orifice
Male: much longer about 20 cm it goes from the bladder through the center of the prostate gland curves around the entire penis and then exits the body at the tip of the penis
–Conveys urine and semen
Composition of urine
Consist of 95% water and 5% dissolved substances which include nitrogenous waste as well as other solutes
urine characteristics: pH
- normal findings
- possible abnormalities
normal
–Average of 6.0
abnormalities
- -A high pH reflects alkalosis
- -A low pH indicates acidosis
Urochrome
Pigment resulting in urine’s yellow colour
Oliguria
urine output of less than 400 mL per day
Most adults produce 1 to 2 L of urine a day
Urination
Also called micturition or voiding
Begins when external sphincter muscle a bladder voluntarily relaxes and the detrusor muscle of the bladder contracts
how urination works
- Bladder contains 200 mL or more of urine stretch receptors in the bladder wall send impulses to the sacral region of the spinal cord
- Spinal cord then sends motor impulses to the bladder wall to contract and to the internal sphincter to relax
- –When this happens voiding will occur in voluntarily unless the brain overrides the impulse - The brain has the ability to override the impulse to void because the stretch receptors in the bladder also send impulses to the micturition center in the pons
- –The Ponds integrates information from the stretch receptors with info from other parts of the brain and evaluate whether the time is appropriate to urinate - If the time to urinate is not appropriate for Braden since impulses to inhibit urination and to keep the external urinary sphincter contracted
- –If the time to urinate is appropriate the brain send signals to the bladder wall to contract and to the external urethral sphincter to relax at which voluntary urination occurs
Life lesson: aging and the urinary system
kidney shrink
Number of nephrons decline
Glomerular filtration slows down making the kitties less efficient removing waste from blood
Bladder shrinks
External sphincter weakens
Renal insufficiency
results when an extensive number of nephrons have been destroyed through disease or injury impairing the ability of the kidneys to function which may occur suddenly as acute renal failure or overtime as chronic renal insufficiency
Acute renal failure
the kidneys often stop functioning as a result of an infection, drugs or an injury after the case of the renal failure is treated kidney function may return to normal
Chronic renal insufficiency
developed over years typically a disease gradually destroys the nephrons eventually damage becomes so extensive that kidneys can no longer effectively clear blood plasma of waste and the damage is irreversible
Hemodialysis
blood is pumped from the patient’s radial artery to a dialysis machine where the blood flows through a series of semi permeable tubes immersed in dialysis fluid
Waste products diffuse out of the blood and into the dialysis fluid which is then discarded
Peritoneal dialysis
the peritoneum serves as a semipermeable membrane
Dialysis fluid is introduced into the peritoneal cavity through catheter and his left in the body cavity for a few minutes to an hour during which waste products that use out of the blood and into the Dallas state which is then drained and discarded
