the urinary system Flashcards
what kidneys dispose of waste products in urine:
-nitrogenous waste
-toxins
-drugs
-excess ions
kidney’s regulatory functions:
-production of renin to maintain blood pressure
-production of erythropoietin to stimulate red blood cell production
-conversion of vitamin D
what is the renal hilum?
-an indention where several structures or exit the kidney
(uterus, renal blood vessels and nerves)
what sits on each kidney?
an adrenal gland
what are the three protective layers that enclose the kidney?
-renal cortex- outer region
-renal medulla- deeper region
-renal pelvis- medial region that is a flat, funnel-shaped tube, collects urine and sends to bladder
how does blood enter and exit?
-blood enters via renal artery and exists via renal vein
pathway of blood flow in the kidney
- aorta
- renal artery
- segmental artery
- interlobar artery
- arcuate radiate artery
- cortical radiate artery
- afferent arteriole
- glomerulus
- efferent arteriole
- peritubular capillaries
- cortical radiate vein
- accurate vein
- interlobar vein
- renal vein
- inferior vena cava
what does the glomerular capsule do?
-filtration
-porous capillaries adapted for absorption
-high pressure forces fluid and solutes out of blood into the glomerular capsule
peritubular capillary beds
arise from the efferent arteriole of the glomerulus
-low-pressure, porous capillaries
-adapted for absorption instead of filtration
-cling close to the renal tubule
three major renal processes
- glomerular filtration
- tubular reabsorption
- tubular secretion
glomerular filtration
-water and solutes smaller than proteins are forced through the capillary walls and pores of the glomerular capsule into the renal tubule
tubular reabsorption
-water, glucose, amino acids, and needed ions are transported out of the filtrate into the tubule cells and then enter the capillary blood
tubular secretion
H1
K1
creatinine
and drugs are removed from the pertitubular blood and secreted by the tubule cells into the filtrate
what is urea
end product of protein breakdown
what is uric acid
results from nucleic acid metabolism
creatinine
associated with creatine metabolims in muscles
why is secretion important
-getting rid of substances not already in the filtrate
-removing drugs and excess ions
-maintaining acid-base balance of blood
-materials left in the renal tubule move toward the ureter
what is filtrate
-filtrate contains everything that blood plasma does (except proteins)
what is urine
urine is what remains after the filtrate has lost most of its water, nutrients, and necessary ions through reabsorption
-urine contains nitrogenous wastes and substances that are not needed
urine characteristics
-in 24 hours, about 1.0 to 1.8 liters of urine are produced
-clear and pale to deep yellow in colour, due to pigment from the destruction of haemoglobin and solutes
-sterile at the time of formation
-slightly aromatic and acidic (pH 6)
abnormal characteristics in urine
-glucose
-proteins
-pus (white blood cells and bacteria)
-red blood cells
-haemoglobin
-bile pigment
glucose meaning
-excessive intake of sugar or diabetes
proteins meaning
-physical exertion
-pregnancy
-glomerulonephritis
-hypertension
pus (white blood cells and bacteria) meaning
-urinary tract infection
red blood cells
-bleeding in the urinary tract (due to trauma, kidney stones, infection)
haemoglobin
-transfusion reaction
-anaemia
bile pigment
-liver disease (hepatitis)
what is the bladder
-a smooth, collapsible, muscular tract
-stores urine temporarily
what does the urethra do
-carries urine from the urinary bladder to the outside of the body by peristalsis
-females-carries only urine
-males- carries urine and spine
what controls the release of urine?
sphincters
what do stretch receptors do?
-stretch receptors transmit impulses to the sacral region of the spinal cord to stimulate contractions
urinary bladder in adult male
-the prostate surrounds the neck of the urinary bladder
-prostate enlargement and severe constipation with age can cause urinary retention
-high risk of urinary tract infection
what is micturition?
-voiding, or emptying of the urinary bladder
how does micturition happen- step 1
-two sphincters control the release of urine, the internal urethral sphincters and external urethral sphincters
how does micturition happen- step 2
-stretch receptors transmit impulses to sacral region of the spinal cord
how does micturition happen- step 3
-impulses travel back to the bladder, via the pelvic splanchnic nerves to cause bladder contractions
how does micturition happen- step 4
-when contractions become stronger, urine is forced past the involuntary internal sphincter into the upper urethra
how does micturition happen- step 5
-urge to void is felt
-the external sphincter is voluntarily controlled, so micturition can usually be delayed
which part of the urinary system develops first
-the kidneys begin to develop in the first few weeks of the embryonic life and are excreting urine by the third month of the foetal life
control of the voluntary urethral sphincter
begins at 18 months
what happens to filtration in old age
-filtration rate decreases and tubules become less efficient at concentrating urine, leading to urgency, frequency and incontinence
what is common for older men?
-urinary retention due to prostate gland enlargement
what is common for older people?
-urinary tract infection (UTIs)
-due to Escherichia coli
