12.1 Flashcards
Chicken: located at the base of the beak; nares can be surrounded by
feathers or may be tubular in structure
Nostrils
In contrast to mammals, they are arranged in
a rostrocaudal, rather than dorsoventral, sequence
Nasal Conchae
Composed of rostral nasal concha (concha nasalis rostralis), middle
nasal concha (concha nasalis media), caudal nasal concha (concha
nasalis caudalis).
Nasal Conchae
The nasal cavity communicates with a single paranasal sinus, the
infraorbital sinus.
presents as a conspicuous mound in the ventral oropharynx, caudal
to the tongue
Larynx
x is to prevent access of foreign
matter to the deeper airways through reflex closure of the glottis. It
does not contribute to phonation
LArynx
shaped like a ‘sugar scoop’
cricoid cartilage
paired; resembles a tuning fork
with its tines directed caudally
arytenoid cartilage
a is supported by a series of cartilaginous rings, Except in
pigeons, these tend to become ossified
Trachea
resemble a signet ring, with the expanded portion alternately forming
the left and right half of each subsequent ring
tracheal rings
extend along the length
of the trachea
tracheal muscles
muscles in trachea
m. tracheolateralis
m. cleidohyoideus,
m. sternotrachealis and
m. cleidotrachealis
located at the level of the bifurcation of the
trachea into the primary bronchi
Syrinx
x function in a similar manner to the vocal
folds of the mammalian larynx.
syrinx
s are present in song birds and absent in domestic
poultry
Syringeal muscles
is
divided into a large and a small cavity and is believed to act as a
resonance chamber
syringeal
bulla
occupy a dorsal position, on either side
of the vertebral column. They are not lobed. The ribs are deeply
embedded in the dorsomedial portion of the lungs, forming
distinctive impressions (sulci costales) that separate the lung tissue
into segments known as tori intercostales
Lungs
The divisions of the bronchi are as follows:
two primary bronchi
secondary bronchi
parabronchi
air capillaries (pneumocapillares)
referred to as first-order bronchi
Primary Bronchi
Walls contain incomplete C-shaped rings of cartilage
Primary Bronchi
is surrounded by respiratory epithelium, underlain by elastic
and collagen fibres, seromucous glands and lymphoreticular tissue
lumen
An adventitia of loose connective tissue is present
Primary Bronchi
Secondorder Bronchi
Secondary Bronchi
the ‘new lung’
neopulmo.
. All birds have the
remaining sectors, referred to as the ‘old lung’
paleopulmo
the functional units of the avian lung
Parabronchi
Interconnects the secondary bronchi; arranged in a parallel array of
elongated tubules, hence it is called ‘air pipes’
Parabronchi
Intimately intermeshed with a dense network of blood capillaries,
permitting gas exchange to take place across the blood–gas barrier
Air capillaries
avian blood–gas barrier is considerably thinner than that of
mammals.
Air capillaries
are thin-walled deformable cavities attached to the lungs
Air Sacs
They provide mechanical ventilation of the lungs by acting as a
bellows
Air Sacs
also serve to pneumatise the
skeleton
Air Sacs
The unpaired air sacs develop
embryonically as paired structures,
fusing at hatching to give rise to
a cervical air sac
a clavicular air sac
Located more caudally are the
paired:
cranial thoracic air sacs
caudal thoracic air sacs
abdominal air sacs
communicate with the secondary bronchi except the
abdominal air sacs, which are connected directly to the primary
bronchi
air sacs
cranial air sacs:
- cervical air sac
- clavicular air sac
- cranial thoracic air sac
caudal air sacs:
- caudal thoracic air sac
- abdominal air sac
consists of a median chamber
lying over the oesophagus, and
two elongated diverticulae that
extend cranially into the vertebral
canal and the transverse canal of
the cervical vertebrae
Cervical Air Sac
is capacious and complex
envelops the heart, the great
vessels at the base of the heart
and the syrinx, as well as
penetrating the humerus and
extends between the muscles of
the pectoral girdle
Clavicular Air Sac
Located between the horizontal
and oblique septa.
They have no diverticulae.
The caudal thoracic air sacs are
small in the chicken and absent in
the turkey.
Air sac perfusion anaesthesia is
usually performed via the left
caudal thoracic air sac
Cranial and caudal
thoracic air sacs
project around the abdominal
viscera
Their volume far exceeds that of the
other air sacs, with the right being
larger than the left.
Dorsally they lie against the kidneys,
as well as the testes in the male.
Diverticulae extend as far as the hip
joint and penetrate the synsacrum
and the ilium.
The abdominal air sacs play a key
role in the mechanical ventilation of
the lungs.
Abdominal air sacs
Movement of air through the lung–air sac system is brought about by
raising and lowering of the caudal margin of the sternum, and by
movement of the ribs
Avian Respiration
The muscles contributing to inspiration are the:
mm. levatores costarum,
m. scalenus,
mm. intercostales externi
The muscles of expiration are the:
mm. intercostales interni,
muscles of the abdominal wall
Organs of the Digestive System
Oral Cavity and Pharynx
Esophagus
Stomach
Small Intestines
Large Intestines
Cloaca
the mouth and pharynx of birds constitute a combined cavity that is
surrounded dorsally and ventrally by the
beak
This macroscopically and functionally common space is referred to
as the
oropharynx
is a distinctive feature of the class Aves
beak
is a particular avian adaptation for feeding, it also
makes a significant contribution during flight as an aerodynamic
feature
beak
form the bony foundation of the beak
maxilla and mandibles
In
many species this is continuously replaced, in a manner similar to a
fingernail. Thus, if the beak of pet birds is not exposed to natural
wear, appropriate trimming may be required
rhamphotheca
These bones are covered in a horny sheath
rhamphotheca
dorsal median ridge of the upper beak
Culmen
ventral midline structure equivalent to culmen
Gonys
a hard horny plate at the tip of the upper and lower beak in
many waterbird species
Nail
- the cutting edge of the upper and lower beak, where the
inner and outer layers of horn come together
Tomium
in several species, a sharp calcified projection found
on the culmen of full term chicks; used by young birds during
hatching to break the egg membrane and sometimes also to
penetrate
the shell; lost shortly after hatching
‘egg tooth
, the beak is pointed and hooked,
Galliformes
) it is flattened
into a spoon-like shape
Anseriformes
In some species, the latter region is thickened forming a structure known as
cere
Transversely oriented ________ on the edges of the rhamphotheca of ducks
and geese assist in the filtration of food
lamellae
In most avian species, the tip of the beak contains multiple
aggregations of sensory receptors that form part of a complex
sensory structure known
bill tip organ.
The sensory receptors are housed within so-called
‘touch papillae’
- forms the dorsal boundary of the combined cavities, or
oropharynx
Palate
in the palate
connects the oropharynx with the left and right nasal cavities
median cleft (choana)
having a mechanical function in transporting food and guarding
against the ingestion of oversized foreign bodies
papillae (
is covered by a non-glandular, often keratinized mucosa
featuring transverse ridges and shallow grooves studded with
numerous caudally directed papillae (galliformes and anatidae)
having a mechanical function in transporting food and guarding
against the ingestion of oversized foreign bodies
palate
lies caudal to the choana which connects with the
middle ear; analogous to the auditory tube in mammals
infundibular cleft
shape and development
varies markedly, according to diet
Tongue
body of the tongue is supported
by a bone,
paraglossum
differs markedly from the hyoid
apparatus of mammals
hyobranchial apparatus
surrounds the
slit-like glottis, the entrance to the
laryngeal cavity
laryngeal mound
ducts of polystomatic
salivary glands open at the base
of the mound
true
Salivary Glands
Maxillary salivary gland
Palatine glands
Rostral and intermediate
mandibular glands
Lingual glands
Sphenopterygoid glands
, the
cricoarytenoid glands and the
caudal mandibular glands
Sphenopterygoid glands
The alimentary canal consists of the following components:
esophagus:
- crop (ingluvies)
stomach (gaster):
- proventriculus
- ventriculus, gizzard
intestine (intestinum):
- small intestine: duodenum, jejunum, ileum
- large intestine: caeca, rectum
cloaca:
- coprodeum,
- urodeum and
- proctodeum
At the thoracic inlet, the esophagus widens to form the crop that, in
most species, lies ventrally
Esophagus
is formed by the dilation of the esophagus immediately before
its entry into the body cavity
crop
Permits temporary storage of ingesta as well as softening and
predigestion of poorly digestible foodstuffs
crop
also produces a substance known as ‘crop milk’,
which is regurgitated and fed to nestlings
columbiform crop
glandular stomach
Proventriculus
Muscular stomach, ‘gizzard’
Ventriculus
are sometimes referred to as a ‘masticatory organ’ as it
replaces the function of the teeth
Gizzard
is shorter in relative terms than in domestic
mammals.
intestine
e is longer in grain- and grassfeeders than in carnivores.
e intestine
are present in all segments of the intestine
Villi
Chemical digestion and absorption of nutrients takes place in the
intestine.
is responsible for breakdown of cellulose, and
reabsorption of water occurs in the rectum and cloaca
caecum
are most conspicuous near the Meckel’s
diverticulum, in the distal jejunoileum and at the entrance
to the caecum
Peyer’s patches
jejunum and the ileum are sometimes referred to collectively as
the
jejunoileum
an embryonic remnant of the yolk
stalk, located on the ansa axialis
(an intestinal loop in the middle of
the jejunoileum), opposite the
longest middle branch of the
cranial mesenteric artery
Meckel’s diverticulum
often
considered to represent the
boundary between the jejunum
and ileum,
rudimentary structure
particularly well developed in the chicken; At its base, each caecum is
richly endowed with lymphatic tissue, sometimes referred to as the
cecal tonsils
Ceca
- the site of digestion of plant
polysaccharides such as cellulose
Ceca
the common excretory passage for the digestive and urogenital
systems
Cloaca
continous with rectum
Coprodeum
ureters and genital duct (male: deferent ducts; female: left oviduct) open
Urodeum
Terminal section; cloacal bursa (bursa of fabricius) pens in the dorsal wall; in
males, houses the copulatory organ (phallus) on its floor
Proctodeum
- external opening of the cloaca
Vent
allow the cloaca to expand for
copulation, egg laying and defaecation
Cloacal muscles
) surrounds the vent
A muscular sphincter
, excreting toxic nitrogenous compounds
(particularly ammonia) in the form of a considerably less harmful
metabolic product (uric acid) in the urine.
uricotelic
Birds lack the enzyme _____ ______(uricase) and are therefore
unable to convert urate into allantoin.
urate oxidase
is absent in birds. This reduces bodyweight, and
thus facilitates flight. Urinary components are excreted together with
the feces
A urinary bladder
presence of an avian
renal portal system
embedded dorsally in excavations of the synsacrum
Kidneys
lie medial to the cranial pole of
the kidneys
adrenal glands
both kidneys is in contact with the paired
abdominal air sac
mucous stringy urine is ultimately deposited
by the ureter into the urodeum of the cloaca.
viscous
emerges from the ventral surface of the kidney in the region of the
middle renal division
Ureter
develop to functional maturity in most avian species.
left ovary and
oviduct
Those on the right side of the body rapidly ________ after hatching,
remaining throughout life as rudimentary structures that may be
filled with fluid.
y regress
is located craniodorsally in the
intestinal peritoneal cavity
Ovary
In the juvenile and non-laying
mature female chicken,
the _____ is a compact, roughly
triangular structure, measuring
approximately 15–20mm by 10mm
and weighing around 0.5g; its
surface has a finely granular
appearance
Ovary
contains the ovarian follicles, comprising
oocytes surrounded by follicular epithelium
cortex
, the macroscopic separation between cortex
and medulla becomes less distinct and is eventually completely
obliterated
sexual maturity
is the
largest female gamete in the
animal kingdom
mature oocyte of birds
is
equivalent to the tertiary, or
Graafian, follicle in mammals
pre-ovulatory follicle
is connected to the
ovary by a peduncle into which
blood vessels, nerves and smooth
muscle cells are drawn
follicle
is filled with a
yolk.
follicle
The post-ovulatory follicle is
capable of producing
________, thus functionally
resembling the mammalian corpus
luteum
progesterone
Oviduct
consists of the:
infundibulum
magnum
isthmus
uterus
vagina
consists of a funnel-shaped proximal
section and a tubular distal portion
Infundibulum
In contrast to mammals, the
infundibular opening is surrounded
by relatively few
fimbriae
of the
oocyte by the spermatozoa occurs
in this segment.
Fertilisation
glycoproteins and phospholipids
secreted by the glands are laid
down around the oocyte to form the
chalaziferous layer
This inner dense
layer of albumen later forms the
twisted _______ that suspend the
yolk as it rotates about its
longitudinal axis
chalazae
the longest and broadest segment
of the female genital tract
Magnum
The glands in the magnum
produce ovalbumin, ovotransferrin
and ovomucoid. These
hygroscopic proteins form the
main component of the albumen,
to which water is added in
the uterus.
true
The time spent by the oocyte (or
zygote) in the magnum is
approximately
three hours
The oocyte (or zygote) passes
through theisthmus in around 1.5
hours.
Isthmus
The oocyte (or zygote) passes
through theisthmus in around
1.5
hours.
later forms in the space
between these membranes, at the
blunt end of the egg. More albumen
is also added in the isthmus.
air cell
sometimes also referred to as the
‘shell gland’
Uterus
The final component of the
albumen is laid down in the uterus,
and the addition of a large
amount of water substantially
‘plumps up’ the hygroscopic mix
of proteins that make up the
completed ‘egg white’
true
The egg spends around_____ in
the uterus
20 hours
Most of this time is occupied by
the formation of the calcareous
shell from calcium carbonate and
other calcium salts. The organic
matrix of the shell is produced
from secretions of the columnar
epithelial cells.
Uterus
The thin, organic outermost layer
of the egg, known as the _____, is
also derived from the uterus
cuticle
With tubular utero-vaginal sperm host glands that serve as storage
sites for sperm near the m. sphincter vaginae at the junction
Vagina
These reservoirs are remarkable in that they can house viable sperm
for some weeks, allowing a female chicken to lay fertilised eggs for
up to two weeks after mating (the closest equivalent is the bitch, in
which sperm can be stored for a week).
Uterus
The time taken for the egg to pass through the vagina is highly
variable with an average range of
5–10 minutes
The male genital organs are
comprised of the:
testes
epididymis
deferent ducts (ductus deferens)
copulatory organ (phallus)
accessory organs of the phallus
like those of
mammals, are paired. However,
as in elephants and cetaceans,
the testes do not undergo descent
testes
Accordingly, birds also lack a
scrotum
are located high in the body cavity,
between the lungs and the cranial renal division, adjacent to the
adrenal glands, aorta and the caudal vena cava
Testes
lies against the dorsomedial
surface of the testis, extending
along approximately two-thirds of
the testicular border
Epididymis
s is not
divided into segments
epididymis
follows a
strongly meandering course,
occupying a retroperitoneal
position
ventromedial to the kidney
e deferent duct
, as in mammals, is
to convey mature sperm
ductus deference
The ductus deferens opens at
the ostium ductus
deferentis located on the
conical papilla ductus
deferentis (particularly
prominent in chickens) in the
urodeum
true
of the male bird is a
component of the cloaca
Phallus
Among modern bird species
there are two types of phallus:
non-protrusible
protrusible, intromittent
