ANATOMY - Avian Flashcards
What are the two principles of flight?
Weight reduction
Power generation
What are the seven functions of feathers?
Streamlining
Reduce friction
Increase surface area
Protection
Contribute to thermoregulation
Camouflage
Communication
What are the two main types of feathers found on avian species?
Contour feathers
Covert feathers
What are the two types of contour feathers?
Flight feathers (remiges)
Tail feathers (retrices)
What is the function of flight feathers?
Flight feathers provide lift and stability during flight
What is the function of tail feathers?
Tail feathers allow for steering and manoeuvring during flight
Label the following structures on this contour feather
What is the function of the hooklets found in feathers?
Hooklets interlock the barbules to create a sturdy and cohesive structure to maintain the overall shape and integrity of the feather
Describe briefly how feathers develop in avian species
Feathers develop from vascular dermal papillae located within feather follicles. Epidermal cells will proliferate within a vascularised, protective corneal sheath to form the blood/pin feathers. As the feather continues to develop, the vascular supply will regress and the corneal sheath will break away, revealing the mature feather underneath
What is a key indicator that a bird has undergone stress during feather development?
Fault bar formation within their feathers
How should you carry out wing trimming?
Trim the first four primary flight feathers annually
What is the propatagium?
The propatagium is the elastic fold of skin extending from the shoulder to the carpal joint, making up the leading edge of the wing
(T/F) Avian species have no sweat or sebaceous glands
TRUE.
What is the average body temperature for birds?
40 - 41°C
What are the five mechanisms used by avian species to cool down?
Expose underwing
Panting
Ruffle feathers
Wetting abdomen
Expose legs
Why do avian species expose their legs to cool down?
Avian species have a counter-current mechanisms, i.e. a network of blood vessels in their legs where warm arterial blood flows alongside cool venous blood, allowing for heat exchange to occur with the warm arterial blood cooling down as it passes the cool venous blood
Where is the uropygial (preen) gland located?
The uropygial (preen) gland is located on the dorsum of the tail
What are the functions of the secretions produced by the uropygial (preen) gland?
The secretions from the uropygial (preen) gland are used during preening to maintain the condition of the feathers along with waterproofing and ectoparasite control
What are the five structural adaptations of the axial skeleton in avian species which contribute to their flying ability?
Pneumatised bones
Beak/bill
Fused vertebrae
Sternum will deep keel
Pectoral girdle
What are pneumatised bones?
Skeletal pneumaticity is the presence of air spaces within bones
Why do birds have a beak?
Birds have a beak because is it more lightweight than teeth and muscles of mastication, allowing them to be more lightweight for flying
Which structural adaptation of the skull allows birds to have increased mobility of their head?
Birds only have one occipital condyle which increases the mobility of their head
What is the function of the cranio-facial hinge?
The cranio-facial hinge is a joint between the upper beak and the skull which allows for increased mobility of the beak during feeding
What is the function of the quadrate bones?
The quadrate bones act as a hinge between the lower beak and the skull to increase the movement and flexibility of the beak during feeding
Which region of the eye is prone to haemorrhage in avian species?
The highly vascularised pecten attached to the retina is prone to haemorrhage
What is the function of the salt nasal gland found in shorebirds?
The salt nasal gland is involved in osmoregulation
How many cervical vertebrae do avian species have?
8 - 25 cervical vertebrae
What are the three regions of the fused vertebrae found in avian species?
Notarium (T3 - T5)
Synsacrum
Pygostyle
What is the function of the deep keel present on the sternum of avian species?
The deep keep of the sternum increases the surface area for the attachment of flight muscles
Which bones does the deep keel of the sternum articulate with?
Coracoid bones
What are the four structures that make up the pectoral girdle in avian species?
Coracoid bones
Scapulae
Clavicles
Furcula
What is the function of the pectoral girdle in avian species?
The pectoral girdle forms a stable base for the wings to generate lift and propulsion
What are the six bones of the avian forelimb (wing)?
Humerus
Ulna
Radius
Alula
Metacarpal
Manus
What is the function of the alula?
The alula prevents stalling when a birds is coming in to land
Which vein of the avian forelimb (wing) is used for venepuncture?
Brachial vein (wing vein)
What are the four bones of the avian hindlimb?
Femur
Tibiotarsus
Tarsometatarsus
Digits
What is the function of the deep digital flexor tendon (DDFT) in avian species?
In avian species, the deep digital flexor tendon (DDFT) tenses passively to clamp the digits around a perch
What are the two primary flight muscles?
Pectoralis muscle
Supracoracoideus muscle
What are the points of origin and insertion of the pectoralis muscle?
Origin: Deep keel of sternum
Insertion: Humerus
What is the function of the pectoralis muscle?
The pectoralis muscle allows for downward stroke of the wing during flight
What are the points of origin and insertion of the supracoracoideus muscle?
Origin: Deep keel of sternum
Insertion: Dorsal humerus via a tendon
What does the tendon of the supracoracoideus muscle pass through to insert onto the dorsal humerus?
Triosseus canal
What is the function of the supracoracoideus muscle?
The supracoracoideus muscle raises the wing during flight
Which jugular vein is more easily accessible in birds?
Right jugular vein
Why do birds only have a single body cavity?
Birds only have a single body cavity as they do not have a diaphragm
What is the name of the single body cavity present in birds?
Coelomic cavity
Which aortic arch does the avian aorta develop from?
Right fourth aortic arch
How many chambers does the avian heart have?
Four chambers
Which organ surrounds the avian heart?
The liver surrounds the avian heart
What is the structure of avian erythrocytes?
Nucleated erythrocytes
What are ceres?
Ceres are a fleshy, membranous covering through which the nostrils (nares) open
What is the most significant paranasal sinus in birds?
Infraorbital sinus
Which structure allows the oral cavity to communicate with the nasal cavity?
The nasal cavity communicates with the oral cavity via the choana
(T/F) Birds have incomplete cartilaginous tracheal rings
FALSE. Birds have complete cartilaginous tracheal rings
Which structure in the avian respiratory tract is responsible for vocalisation?
Syrinx
What is the syringeal bulla?
The syringeal bulla is an enlarged region of the syrinx in some species of bird which adds resonance to the sound produced
Describe the structure of the avian lower respiratory system
Birds have a system of air sacs throughout their body which connects to their lungs
What are the three cranial air sacs?
Cervical air sac
Clavicular air sacs
Cranial thoracic air sacs
What are the two caudal air sacs?
Caudal thoracic air sacs
Abdominal air sacs
Which breathing pattern is used by birds?
Unidirectional breathing
Describe the unidirectional breathing pattern in avian species
During the first inhalation, some air enters the lungs and undergoes gaseous exchange, while the rest of the air flows into their caudal air sacs. During the first exhalation, this fresh air moves from the caudal air sacs into the lungs for gaseous exchange. During the seconds inhalation,the stale air in the lungs flows into the cranial air sacs. Then, during the second exhalation, the stale air in the cranial air sacs flows out through the trachea
What allows for such efficient gaseous exchange within the avian lungs?
The avian lungs have a network of pathways known as parabronchi which have a continuous network of air capillaries in their walls which have a close association with blood capillaries, allowing for more efficient gaseous exchange
What is the protective, keratinised sheath surrounding the beak?
Rhampotheca
What is the crop?
The crop is a blind-ending diverticulum that out-pouches from the oesophagus and acts as a temporary storage area
What are the two regions of the avian stomach?
Proventriculus
Gizzard
What is the function of the proventriculus of the avian stomach?
The proventriculus is the glandular region of the avian stomach
What is the function of the gizzard of the avian stomach?
The gizzard is the muscular region of the avian stomach
What is the site of fermentation and water reabsorption in the avian gastrointestinal system?
Paired caeca
What is the cloaca?
The cloaca is the point of exit for the digestive, urinary and reproductive system in birds
What are the three structural divisions of the cloaca?
Coprodeum
Urodeum
Proctodeum
What is the vent?
The vent is the sphincter that controls the expulsion of material from the bird
(T/F) In avian species, the right gonads are functional however the left gonads are vestigial
FALSE. In avian species, the left gonads are functional however the right gonads are vestigial
Where does fertilisation take place in the avian female reproductive tract?
Infundibulum
Which component of the egg is produced in the ovaries of the female reproductive tract?
Egg yolk
Which component of the egg is produced in the magnum of the female reproductive tract
Albumen (egg white)
Which component of the egg is produced in the isthmus of the female reproductive tract
Shell membranes
Which component of the egg is produced in the uterus of the female reproductive tract
Egg shell
What is the function of the sperm host glands in the avian vagina?
Sperm host glands store sperm and are mechanically stimulated by the expulsion of an egg to release the sperm which will then travel to the infundibulum of the oviduct for fertilisation
How many lobes do the avian kidneys have?
Avian kidneys have three lobes
Birds have both mammalian and reptilian nephrons. What does this mean?
Birds have nephrons both with and without loops of Henle so are able to produce concentrated urine and conserve water but not as efficiently as mammals
How do birds excrete their nitrogenous waste?
Birds excrete their nitrogenous waste as uric acid
Why is uric acid redirected to the paired caeca before being excreted from the vent?
Uric acid is redirected to the paired caeca for further water reabsorption before being excreted from the vent
Which aspect of avian renal function confers an advantage over the mammalian system?
Nitrogenous waste is secreted as uric acid which prevents its reabsorption and benefits water conservation
What is the function of the renal portal valve in avian species?
The renal portal valve is a smooth muscle valve that can direct blood flow from the posterior extremities to either the caudal vena cava or through the kidneys
Do birds have a urinary bladder?
No, birds do not have a urinary bladder
Identify these ventral neck structures
Identify these coelomic cavity structures
Identify these coelomic cavity structures
Identify these structures of the avian gastrointestinal tract
Identify these structures of the avian gastrointestinal tract
Identify these structures of the avian female reproductive tract
