avian nephrology Flashcards
avain adapations are related to ability to ____
fly
- aerodynamic
- weight reduction
- flight/migration stamina
what do birds lack in their urinary tract
urinary bladder and urethra, instead they have a cloaca
where do the kidneys sit
renal fossa of synacrum in the coelom
what is the synsacrum
depression in lumbar spinal column
what are the 3 sections of the kidneys
- cranial pole
- middle pole
- caudal pole
the kidneys are in close associated with ____ and ____ plexi
lumbar and sacral
in the microscopic anatomy of the kidney, what do birds lack?
- distinct single cortex and medulla
- no renal pelvis
what are the two different types of nephrons
cortical
* akin to reptiles
* most abundant
* uric acid through glomeruli into PCT; NO LOOP OF HENLE
medullary
* akin to mammals
* have loop of henle in medullary region
* forming/concentrating urine
* more abundant in birds from deserts
ureters lined by and secrete
- lined by pseudostratified columnar epithelial cells
- mucus secretion
what does mucus secretion aid in
passing of urates
where do the ureters enter
urodeum
parts of cloaca
- coprodeum
- urodeum
- proctodeum
- vent
- bursa
coprodeum
- cranial compartment
- rectum empties; part of colon
- separates urodeum by coprourodeal fold (vital for mixing of GI and Uro contents)
urodeum
- middle compartment
- ureters and genital ducts empties here
- can retropulse urine from urodeum to coprodeum and intestines for water resorption
proctodeum
- short compartment
- empties into vent
- bursa on dorsal wall
vent
- external opening of cloaca
- variably shaped
- muscular sphincter controls for excretion and copulation
bursa
- dorsal extension of proctodeum
- unique to birds
- site of B cell maturation
- regresses with age
what are salt glands
- present in all birds
- most prominent in sea birds (drink salt water; excretion of salt)
- prominent in birds from arid climates
- countercurrent blood flow removes salt from blood
- pass from nasal passages to be sneezed out
where are the adrenal glands
- cranial to kidneys and gonads
- adjacent to aorta and caudal vena cava
adrenal glands microanatomy
cortex not well differentiated from the medulla
what hormones are secreted where in the adrenal gland
- adrenaline and norepinephrine secreted by medulla
- corticosterone (glucocorticoid and mineralocorticoid) and aldosterone from cortex
desert birds conserve water with:
- more medullar nephrons concentrate urine more efficiently
- cooling warm air through blood supply in the nares
- ~20-40% less water in excrement in birds from arid regions
dehydration prevented in migratory birds due to:
- high altitude preventing evaporative water loss
- water produced from metabolizing fat stores
- flying at night (cooler air)
what are the 3 components of avian droppings
- feces: brown/green part made of solid waste
- urates/uric acid: byproduct of protein catabolism which is white and chalky
- urine: liquid component; usually clear
