Urinary Flashcards
What are 4 examples of metabolic waste products?
Carbon dioxide and water
Nitrogenous wastes (urea)
Bile salts and pigments
Various salts
What are the 4 routes for waste product elimination?
Respiratory system - carbon dioxide, water vapor
Sweat glands - water, salts, urea
Digestive system - bile salts, pigments
Urinary system - urea, salts, water, other soluble waste products
What are the 4 parts of the urinary system?
Kidneys
Ureters
Urinary bladder
Urethra
What is the primary function of the kidney?
Production of urine to facilitate elimination of metabolic waste materials
How do the kidneys maintain homeostasis?
Blood filtration, reabsorption, secretion
Fluid balance regulation
Acid-base balance regulation
Production of hormones
Blood pressure regulation
What hormones help in fluid balance regulation?
Antidiuretic hormone (ADH) and aldosterone
What hormones are produced in the kidneys?
Erythropoietin, prostaglandins
The kidneys are located _______________ to the abdominal cavity
Retroperitoneal
Which kidney is located more cranially except in pigs?
Right kidney
What is the hilus and what does it contain?
Indented area on medial side - ureters, nerves, blood and lymph vessels enter/ leave
What is the funnel-shaped area inside the hilus called?
Renal pelvis
What 3 parts make up the gross anatomy of the kidney?
Renal cortex
Renal medulla
Calyx
What is the basic functional unit of the kidney?
The nephron
What does the nephron contain?
Renal corpuscle
PCT
Loop of Henle
DCT
What makes up the renal corpuscle?
Glomerulus surrounded by the Bowman’s capsule
What happens in the renal corpuscle?
Glomerular filtrate - Blood is filtered by the glomerular capillaries in the first stage of urine production
What is glomerular filtrate called in the PCT?
Tubular filtrate
The DCT is the primary site of what?
ADH action, regulation of potassium and acid-base balance
What does the DCT empty into?
Collecting duct
What nervous system supplies the kidneys and what does it do?
Sympathetic portion of the autonomic nervous system - sympathetic stimulation causes vasoconstriction of renal vessels
How is blood supplied to the kidneys?
Through the renal artery that enters at the hilus
What does the renal artery subdivide into?
Afferent glomerular arterioles
Where is blood carried from the afferent glomerular arterioles?
To the renal corpuscle
What happens in the peritubular capillaries?
Oxygen transfer to cells of nephron
Tubular reabsorption/ secretion occurs here
Where does blood filtration occur?
Renal corpuscle
High blood pressure in glomerular capillaries causes what to happen?
Forces some plasma into capsular space of Bowman’s capsule
Glomerular filtrate lacks what?
Protein
Pores in the capillary endothelium that help transfer plasma out of the glomerular capillaries
Fenestrations
What is the term used to describe how fast plasma is filtered as it passes through the glomerulus and what does it depend on?
Glomerular filtration rate - depends on rate of blood flow to the kidney
What is reabsorption?
When useful substances leave the tubules of the nephron and enter into the blood of the peritubular capillaries
What are the 9 substances that get reabsorbed?
Sodium, potassium, calcium, magnesium, glucose, amino acids, chloride, bicarbonate, water
Where/ how is sodium reabsorbed?
In the PCT, ascending LOH, DCT by a carrier protein
What 3 things is sodium usually exchanged for?
Hydrogen, ammonium, potassium ions
Where are potassium and calcium reabsorbed?
PCT, ascending LOH, DCT
What does calcium move under the influence of?
Vitamin D, PTH, calcitonin
Where is magnesium reabsorbed?
PCT, ascending LOH, CD
What increases the reabsorption of magnesium?
PTH
What happens in response to electrical imbalance created by sodium removal?
Chloride ions diffuse from tubular filtrate into epithelial cells and interstitial space
What happens after sodium, glucose, amino acids and chloride have left the tubular filtrate?
Some of the water in the filtrate moves by osmosis into the interstitial space and peritubular capillaries
___________ is one of the waste products the body wants to get rid of, but some of it also gets reabsorbed and its levels can be measured as the BUN
Urea
Secretion primarily occurs where?
DCT
What waste products are eliminated by secretion?
Hydrogen, potassium, ammonia and some medications
Urine volume regulation is controlled by what two hormones?
Antidiuretic hormone - if absent polyuria results
Aldosterone
How do the kidneys regulate blood pressure?
Renin-angiotensin-aldosterone system - Response to low blood pressure
Renin released - splits angiotensin enzyme
Sodium + water reabsorbed back into bloodstream
Blood volume increases - so does blood pressure
Tubes that exit the kidney and connect to the urinary bladder
Ureters
Arrangement of openings of ureters into the bladder and opening from the bladder into the urethra
Trigone
What part of the kidney do the ureters leave from?
Hilus
What 3 layers of tissue are the ureters composed of?
Outer fibrous layer
Middle muscular layer
Inner epithelial layer
What does the middle muscular layer of the ureters do and what type of muscle is it?
Smooth muscle - propels urine by peristalsis
What does the inner epithelial layer of the ureters allow for?
Allows ureters to stretch when urine passes through
How do the ureters prevent backup of urine into the ureters?
The openings collapse when the bladder is full
What are the two parts of the bladder?
Muscular sac
Neck
What type of epithelium makes up the bladder?
Transitional epithelium - stretches as bladder fills with urine
What muscle contracts to expel urine from the bladder?
Detrusor muscle
What provides voluntary control over the urination process?
Circular sphincter muscles around the neck of the bladder
What are 2 other words used for urination?
Micturition, uresis
What is the process of urine accumulation?
Bladder constantly accumulates urine
Stretch receptors are activated
Pressure of filling of bladder reaches trigger point
What is the process of muscle contraction when the bladder is full?
Spinal reflex activated
Motor impulse sent to detrusor muscle
Smooth muscle in bladder wall contracts
Bladder is emptied if animal not housebroken
What is sphincter muscle control when the bladder is full?
Allows for temporary control of urination
The fuller the bladder, the more pressure on the sphincter muscle
Eventually relaxes - urine released
Where is the urethra located and what does it do?
Continuation of the neck of the bladder - carries urine from the bladder to external environment
What are the characteristics of the female urethra?
Short and straight
Opens on the ventral portion of the vestibule of the vulva
Lined with transitional epithelium allowing it to expand
What are the characteristics of the male urethra?
Long and curved
Runs along the ventral aspect of the penis
Lined with transitional epithelium allowing it to expand
