Avian Phys 4

1. Coracoids—help wing movement and shoulder support

2. Cervical vertebrae—S shape to minimize impact stress

3. Spinal vertebrae—fused for wing movement

4. Lighter bones

5. Hollow bones that are part of the respiratory system—pneumatic bones

6. Medullary bone—source of calcium

Differences in bird skeletons

Skull (23 bones), sternum, vertebrae (42 bones), ribs (14 bones)

Axial skeleton

Walk on their toes

digitigrades

Long bones, short bones, flat bones, irregular

Bone types

Where bones grow in length

epiphyseal growth plate

Grows bone in diameter

IGF-1

Normal bone cell

Osteocytes

deposit calcium and build bones

osteoblasts

resorb bone to release calcium

osteoclast

Striated muscle cells

Cardiac and skeletal

Unstriated muscle cells

smooth

voluntary muscles (can move)

skeletal

involuntary muscles (can’t move)

cardiac and smooth

muscle cells, can’t replicate

myofibers

motor end plate → ACH → nicotine receptor → sodium at proximal end → T tubules → sarcoplasmic reticulum

How muscles are activated

Two parts on actin (thin filament)

Troponin and tropomyosin

Covers binding site when muscle not activated

tropomyosin

acts as a lock for tropomyosin

troponin

when actin binds to myosin

power stroke

spread of action portential through these

T tubules

Calcium is released from

sarcoplasmic reticulum

more work = more time

load velocity

multiunit smooth muscle

neurogenic

single unit of smooth muscle forms this

funtional synctia

How much calcium does a hen deposit in an egg

10%

1. Progressive decrease in structuralized bone

2. bone fragility and fracture

3. 20-35% of mortality in leghorns

4. best cure is excerise!

Osteoporosis

Functions of calcium

build bone, shell formation, muscle contraction, blood clotting

muscle cramps, calcium tetany, cardiac dysfunction

Hypocalcemia

calcium phosphate crystalizes and hurts organs

Hypercalemia

3 pools of calcium

bone, intracellular, circulating extracellular

responds to hypocalcemia, synthesized in skin, liver, and kidney, increase gut absorption of calcium

Calcitriol or vitamin D3

Makes PTH, helps with hypocalcemia, resorbs bone, increase intestinal absorption with D3, reduces loss of urinary calcium

Parathyroid gland

helps with hypercalcemia, inhibit resorption, increase loss of urinary calcium

Calcitonin

genetic, organs match genetics

sex determination

ZW

Female

ZZ

Male

hormonal, brain match organs, estradiol

sex differentiation

puberty

sex activation

cholesterol → pregnenolone →testosterone => Aromatase (estrogen and estradiol) or DHT

sex steriods

1. released from pit. 15hrs prior to ovulation

2. stimulates follicular granulosa development

3. stimulate steroidgenesis in folicular granulosa

FSH

GnRH surge → __ surge; stimulates ovulation

LH

parental behavior, secreted just before parturition, stimulated by VFP, inhibits ovaries, induces broodiness

prolactin

inhibits repro behaviors

GnIH

bit at end of cloaca (like a funnel)

phallic tubercle

Produce testosterone

Leydig cells

spermazoa and liquid component

semen

have large phallic bodies

Anseriformes and ractites

ovary → infundibulum → magnum→ isthmus → uterus → vagina

hen oviduct

only fit sperm reach it, go to sperm storage tubules, 90% sperm lost in 1hr

UVJ

germinal disk right under, sperm have to eat through it, 1-100s of sperm enter

Perivitelline membrane

long term stressors in breeder barn

early death

nutrition, environment, lighting

unfertilized eggs

incubation issue with humidity

late death

storage, transport, sanitizing, incubation, floor eggs

fertile dead