---start anat.lec.11.26.96---

sound production in birds....all birds can vocalize. peter was talking 
about song production being limited to males. females can squawk but not 
sing.

re: double breathing pattern of birds...avian respiratory system - gas 
exchange takes place in the parabronchi of the lung. there are a bunch of 
air sacs - a cranial group and a caudal group of air sacs. there is a 
primary bronchus leading in to the air sacs - it splits into the 
mesobronchi.

when bird inhales, air goes into caudal air sac only. there's a ring of 
smooth muscle at the entry to the cranial sac which contracts to prevent 
airflow from going into the cranial sac, and also has a sphincter around 
the pr bronchus itself, cransial to the cranial sac, propelling air to 
the caudal air sac. note that ALL resp system components expand and 
contract together. with first expiration air goes from caudal air sac 
into lung, and gas exchange occurs. with second inspiration, air goes 
into the cranial air sac from the lung. then with the second expiration 
air goes back into the primary bronchus from the cranial air sac and out 
of the bird.

bird repro

males have no penis, just a phallus type thing sitting at the ventral 
part of the vent. in fowl, they kind of just evert the vent. it's not a 
functional penis...sperm doesn't actually come out of it. it just everts 
and sperm from the deferent duct oozes out of it or something, and it 
puts it near the female's cloaca and hopes for the best.

males do have testes. out of season, they're very small. during breeding 
season they hypertrophy about 300 x - become kidney sized. are located 
internally, ventral to where the kidneys would be. the bird kidneys are 
large, themselves.

birds have no urinary bladder. don't make urea, make uric acid: pasty 
stuff., water saving adaptation. 

in females, there is a functioning oviduct only on the left side, not the 
right. there are a whole bunch of structures inside the females that look 
like yellow grapes: these are the ovary, suspended from mesentery, 
ventral to left kidney. there is a large infundibulum which captures the 
egg as it is released. the oviduct itself is a long windy passageway. the 
part close to the infunibulum is called the magnum. then it narrows and 
becomes the isthmus. the infundibulum, magnum, and isthmus produce the 
albumen of the egg. the isthmus also makes part of the shell membrane. 
finally egg reaches "shell gland" or uterus, then the vagina, is 
relatively narrow, then it's released into the urodeum, where there may 
also be a vestigial right oviduct which would be undeveloped.

don't stress out trying to see urodeum coprodeum and proctodeum in the 
chicken. they're small.

---note: the above is PART OF the bird lecture, will be on exam---

now, dr dodson...he says we may or may not have chickens.
bone demo: manatee rib, heavy, marine adaptation: acts as ballast. bird 
bones - humerus, pelvis, very light. ostrich pelvis is very dinosaurean, 
according to dr d. ostrich femur - very hollow with honeycomb like 
inside.

bird lungs, btw, are small and rigid. they aren't balloonlike like 
mammalian lungs. they're plastered to the dorsal body wall. they don't 
slide against the wall. when you pull the lungs out of a dog, the dorsal 
body wall is smooth. but when you look inside chicken thorax, you see 
each rib projects into thoracic cavity, and the lung tissue is 
interpolated between them...
when you open a dog thorax, you see the lungs, first thing. when you open 
the chicken, you can see the heart, but you have to hunt for the lungs, 
because they are small and dorsal.

the bird heart is about 33% larger than the mammalian heart, but their 
thorax is narrower and smaller - less capacious.

the point is that the contraction and expansion of the air sacs is what 
pushes the air through the lungs in one direction. the lung itself 
doesn't expand/contract much. so the air sacs are very important. but if 
you compromise the air sac, the bird can still breathe.

to tell what sex a bird is...in some cases, it's by phenotype, in other 
cases, you have to do blood tests or genetic testing.

re: air sacs: they look like soap bubbles inside the bird. if you aren't 
careful, you could cut through them. with fresh chickens, you can use a 
straw to put air in through the trachea, and you puff up the chicken and 
then you can see the abdominal and cranial air sacs inflate, and then you 
take your mouth off the straw, and press down on the air sacs and press 
out the air, and if you're lucky the chicken will vocalize. it's like 
playing the bagpipes.

there are reciprocal mechanisms - the elbow/carpus flex at the same tiem, 
and also there's osmething with the perching mechanism in the pelvic 
limb.

look at the preening gland - you can make oily stuff come out of it.

to avoid the feathers, just skin the animal and set the skin and feathers 
aside.

note: both sexes have combs and wattles except in a few species. the 
spur, however, is much larger in the rooster than in the hen.

note the pectoral muscles, the supracoracoideus muscle/tendon. look a bit 
at the pelvic musculature

note the big heart, aortic arch on the right side. left and right 
brachiocephlic trunks, lungs dorsal and small. note absence of diaphragm. 
after skinning the animal try inflating the air sacs again. you may also 
note axillary or clavicular air sacs inflating. you'll see the crop which 
is likely to have stuff in it. in fact, palpate the crop before you do 
any cutting.

birds have high metabolic requirements, so they eat high protein easily 
digestible food, not a lot of plant material. they eat seeds, fruits, 
insects, flesh, fish. very few birds eat plants. leaves and grasses are 
not good foods for birds, who have simple GI tract, poorly differentiated 
large intestine.

south american stink bird, though, does ferment leaves and is a smelly 
bird. its young have claws on wings and they climb up tree trunks. they 
look like archeopteryx.

the cecae are paired and long, having about the same diameter as the 
colon.

there is one bizarre structure to look for on the gut called meckel's 
diverticulum. it's a little button, a remnant of the embryonic yolk sac 
on the antimesenteric side of the small intestine opposite where the 
cranial mesenteric artery supplies the gut...
historically, finding this indicated an auspicious occasion. 
realistically, it's there in younger birds and not in older birds, so 
"reading the auspices" in this way is kind of silly, it all depends on 
the age of the bird.

the oviduct is about 2 feet long., and about 30 cm of that - about half 
of it - is magnum. it takes about 3 hrs for an egg to slide down the 
magnum, during which time it is invested with albumen, and about an hour 
to traverse the isthmus, where it gets shell membrane, and it sits in 
shell gland about 20 hrs, where it gets water and shell (calcium 
carbonate) added.

when you open the abdomen, the first thing you see is ovary, which is 
jsut developing ova.


---end---