6.3 Avian Anatomy Flashcards
How are birds modified for flight?
Forelimbs modified to wings
Feathers - streamline, contour, steering
Bones fused and pneumatised
Large sternum for origin of flight muscles
Triosseal canal - brace between sternum and wing
What are the three main muscles associated with flight?
Triosseal canal
Supracoracoideus muscles
Pectoralis muscles
Describe the triosseal canal
Furcula (fused clavicles)
Coracoid
Scapula
Tendon runs through to connect supracoracoid muscles to humerous
Responsible for lifting wings during recovery stroke
Describe the avian GIT
No teeth
Crop - food storage
Gizzard - mechanical grinding of food
No omentum
Ceca variable
Cloaca - communal termination of urinary and intestinal tract
Bursa of Fabricius (lymphoid tissue in dorsal wall)
Describe the avian repro anatomy
Paired testes
Single left ovary and oviduct (varied egg production)
Many species are sexually monomorphic
Sexing by DNA testing
Describe avian air sacs
9 air sacs (1 clavicular, 2 cervical, 2 cranial thoracic, 2 caudal thoracic, 2 abdominal)
Describe avian trachea anatomy
Large deadspace
Compensate with large todal vol. and low respiratory frequency
Describe avian lung anatomy
Trachea, mesobronchi, ventrobronchi, parabronchi
What are the three forms of calcium in avian species?
Hydroxyapatite - in bone
Intracellular calcium
Extracellular calcium - ionised and protein-bound
What are the three hormones regulating calcium?
Vitamin D3
Parathyroid Hormone
Calcitonin
Describe Vitamin metabolism
Provitamin D -UVB-> Vit D3 (Cholecalciferol)
Cholecalciferol -LIVER-> Calcidiol
Calcidiol -KIDNEY-> Calcitriol
Calitriol is hormonally active metabolite of vit D3 that facilitates absorption, uptake, deposition, and excretion of calcium.
Sex hormone in egg laying birds
Oestrogen effects storage, mobilisation, transport
Describe the role of parathyroid hormone
Produce by parathyroid gland due to low Ca2+
- ↑ renal tubular reabsorption of calcium
- ↑ bone resorption
- ↑ VitD3 -> Calcitriol conversion in kidneys
