Flashcards in Test yourself ?s Chpt. 19 Avian Anatomy and Physiology Deck (48):
What structures are derivatives of a bird's skin and what are they made of?
The beak: Also known as the bill. Is covered with a tough, horny keratin layer that grow continuously.
The claws: Possess a horny sheath derived from specialized scales at the end of each toe. Also grow continuously.
The feathers: Outgrowths of skin that are made of protein. Once completely developed, they are nonliving structures that have sensation only at the base, where they originate from a follicle.
Define the function of the uropygial gland. Do all birds possess this gland?
Also known as the preen gland
The act of preening stimulates this gland to secrete an oily, fatty substance. The bird spreads this oil throughout its feathers using his beak to clean and waterproof them.
Not all birds possess this gland. It is completely lacking in some parrots, ostriches, and in a few other species.
Describe the basic anatomy of a bird's beak and claws. When trimming these structures, what should you be careful to avoid?
Beak: consists of an upper and lower mandible; vary in hardness and flexibility depending on their function.
Claws: horny sheath derived from specialized scales; differ amongst species (ground feeders = short, sharp; prey birds = claws called talons that are long, sharp and rounded; scavengers = short, blunt; climbing birds = strongly curved for gripping)
Do not trim either of them too deeply, as they have a blood and nerve supply.
List three major functions of feathers.
1. Necessary for flight
2. Protect thin skin from trauma, rain and excessive radiation from sunlight
3. Assist in thermoregulation and camouflage as well as many communication behaviors
What type of feathers are the flight and tail feathers? Describe their microstructure.
The contour feathers. In the wing they are called remiges, and the tail are called retrices.
Microstructure: Inferior umbilicus (tiny opening at base, where it inserts into skin); superior umbilicus (tiny opening on shaft, where the webbed part of feather begins); calamus (also called quill, round, hollow, semitransparent portion); rachis (main feather shaft); vane (flattened part of feather appearing weblike on each side of rachis).
Define a fault bar. What causes it?
If a feather is stressed during its growth, there is an interruption in its blood flow and a fault or stress bar develops. This is characterized by a weakened area on the feather vane, where the barbs lack barbules.
The most common stressor is a poor diet.
What is a blood feather?
A growing feather
How do the wing and tail feathers differ between predatory and prey bird species?
Prey species: major flight feathers are loosely seated in the follicles, so they can drop feathers quickly, if grabbed as an aid to escape a predator
Predatory species: feathers are seated very strongly in the follicles, and pulling out a flight or tail feather can result in permanent follicle damage, which prevents a new feather from ever growing in.
Describe the attachment of the skull to the vertebral column. What does this type of attachment provide?
The atlas contains a single condyle (ball and socket type of structure) for attachment to the skull. This allows a greater range of head movements as compared to mammals, which have two condyles.
List the bones in the avian wing from the shoulder to the tip.
1. Humerus containing a pectoral crest for attachment of wing muscles
2. Elbow joint
3. Radius and Ulna
4. Wrist joint (two bones)
5. Alula (first finger)
6. Major and minor metacarpal bones
7. Second and third fingers
List the bones in the avian leg beginning at the hip and extending down to the toes.
1. Hip joint
3. Knee joint
4. Tibiotarsus and fibula
5. Ankle or hock joint
List the two types of skeletal muscle fibers and describe their energy use.
White fibers are thick and have a low blood supply, have little myoglobin for carrying oxygen, and use stores of glycogen to sustain muscle contraction (found predominantly in short distance fliers)
Red fibers are thinner and have a rich supply of blood, fat, myoglobin, and mitochondria. They can produce enough energy to sustain muscle contractions for long periods (found predominantly in long distance fliers)
Why can a bird perch while sleeping?
Extensor tendons run down the front of the tibiotarsus and metatarsus, whereas the flexor tendons run along the back. The flexor tendons sit in a groove at the top of the metatarsus. When a bird bends its legs to perch, the tendons also bend and pull the toes closed around the perch. This is called the perching reflex and allows a bird to firmly grip its perch while sleeping.
What are the two most important senses in birds?
Vision and hearing
Where are the bird's ears located?
On the side of its head, behind and slightly below its eyes.
Name the two types of sensory nerve endings in the skin and tell where they are located.
The first type is called a Grandry's corpuscle. Groups of these are located in the tongue and palate.
The second type is called a Herbst corpuscle. Often located in areas of the mouth. They can also be found in the cloaca, legs, wings, uropygial gland and the bases of many feathers.
Which eye structures are found in birds but not in mammals?
The sclerotic ring and pecten
Which endocrine gland secretes hormones that regulate molting and the migratory urge?
List the endocrine and exocrine functions of the pancreas.
Synthesizes hormones that regulate blood sugar and sugar metabolism in the liver.
Also produces pancreatic polypeptide that inhibits GI motility and secretion and induces a sense of satiety.
On which side of the neck is the esophagus located in birds? Does this differ from mammals?
On the right side of the neck.
It does differ from mammals as theirs is situated on the left side of the neck.
List the two separated components of the avian stomach and their functions.
The glandular stomach: Also called the proventriculus, chemical digestion begins here. It moistens the food. Breakdown of proteins begins here and the action of digestive enzymes is enhanced.
The muscular stomach: Also called the gizzard. It grinds food components.
What is a mute? What can it tell us about the health of a bird?
The consistency of the fecal matter and the color of the urate can give us clues about the health status of a bird. White color is a good sign.
What is the renal portal system?
It begins and ends in a network of capillaries. Blood returning from the extremities via the iliac veins travels to the kidneys. Valves at the junction of the iliac veins and renal veins steer blood either to the kidneys, so metabolic waste products can be removed, or directly to the heart via the posterior vena cava.
What is the body temperature range of birds?
Birds are active creatures and have a relatively high body temperature between 37 and 42*C.
Describe the components of an avian ECG.
P wave - contraction and relaxation of the atria
QRS wave complex - contraction of the ventricles
T wave - relaxation of the ventricles
How do avian red blood cells differ from those in mammals?
Erythrocytes, or red blood cells, are oval, nucleated, and larger than those in mammals.
In passerines (song birds), they are formed in the spleen and liver, not in the bone marrow.
List the three veins that are commonly used for venipuncture in birds. Where are they located?
Jugular vein: ventrally, on each side of the trachea
Brachial vein: ventral side of the wing, extending over the elbow and up the humerus
Medial metatarsal vein: ventral medial side of the leg, extending from the metatarsus dorsally over the heel joint
Where does gas exchange occur in the avian respiratory system?
The parabronchi are small, parallel tubes originating from the ventrobronchi in the lungs and are connected to the tiny openings of air capillaries. The air capillaries, in turn, are surrounded by small blood capillaries. Gas exchange occurs between these two groups of capillaries.
List the nine air sacs and their main function in respiration.
Four are paired and they include cranial thoracic, caudal thoracic, cervical, and abdominal air sacs.
The unpaired sac is the interclavicular air sac, which is located in the thoracic inlet between the clavicles.
1. They act as reservoirs for air and provide warmth and moisture to facilitate the diffusion of air through the lung capillaries.
2. They help in thermoregulation, cooling the body by the internal evaporation of water.
3. They help provide buoyancy to water birds.
Do birds have a diaphragm?
No, they do not.
Describe the path of one breath of air through the respiratory system.
IN - Trachea
Posterior air sacs
Anterior air sacs
Trachea - OUT
What is the major component in the nitrogenous waste of birds? What are the advantages to producing this type of waste?
Uric acid is more efficient in eliminating nitrogen and it conserves water. The production of uric acid is critical to the survival of embryos within the egg. The only waste products that can be eliminated through an eggshell are gases. Other waste products must be stored in the egg throughout the embryo's development.
Explain how sperm is transferred from the male to the female in birds.
In some species, such as ducks, geese, Galliformes, storks, and flamingos, a grooved, erectile penis is attached to the wall of the cloaca to help transfer sperm into the female's vagina.
In most species, however, sperm transfer occurs when the male and female bring their cloacae into proximity.
List the five sections of the avian oviduct and their functions.
1. Infundibulum - possesses folds that grab an ovum as it comes out of the ovary
2. Magnum - secretes layers of albumen (egg white) around the egg
3. Isthmus - deposits the keratin shell membrane
4. Uterus - deposits watery albumen, a hard external shell, and pigmentation; large and muscular, it is also called the shell gland, and an egg spends the most time here
5. Vagina - secretes mucus to assist in egg laying; stores sperm for hours to several days
What is the average incubation temperature?
What is a brood patch and how does it relate to incubation?
An area of skin on the lower abdomen where heat is transferred to the egg. The hen plucks the feathers in this area because of the influence of prolactin, and estrogen stimulates thickening and wrinkling of the epidermis and an increase in the size and number of blood vessels.
Describe the four classifications of newly hatched chicks.
1. Altricial - hatch with eyes closed and skin bare; require a great deal of care before being able to leave nest
2. Semialtricial - hatch covered with down and immobile; eyes may be open or closed
3. Precocial - hatch covered with downy feathers, eyes open and quite mobile, leaving nest quickly
4. Semiprecocial - hatch with downy covering and open eyes; only move short distance from nest and are fed by parents
Fault or stress bar
Weakened area on the feather vane where barbs lack barbules
Results from stress that interrupts blood flow during feather growth
Common stressor: poor diet, thyroid disease, infection,...
Process of feather replacement (most species this is symmetrical)
Many species of waterfowl molt all flight feathers at once after the breeding season
Thyroid hormones stimulate molting, activate cells in papillae
Feather emerges covered by periderm, which is removed by preening
*Lumbar and sacral vertebrae
- strong bony plate created from fusion of several distal lumbar vertebrae, sacral vertebrae, and first few coccygeal vertebrae
- fuses with the pelvis, supports the legs
*One toe faces the rear, other three face forward
*Second and third toes face forward, first and fourth are directed backward
*insertion: underside of humerus
*depresses wing (downstroke)
*insertion: top of humerus
*elevates wing (upstroke)
*Hearing in nocturnal owls
*fleshy flap of skin at each external ear opening
*helps funnel sound into the ears
IT'S ALL A CONSTANT AIR EXCHANGE
*expansion of thoracoabdominal space
*creates pressure gradient that brings air into posterior air sacs
*pushes air into the lungs
*Important part of oviduct
deposits keratin shell membrane
*Dystocia in birds