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First year semester 2 > Repro 3 > Flashcards

Repro 3 Flashcards

1
Q

List the vet definitions of puberty and what this means for male and female

A

Puberty = the acquisition of reproductive competence
MALE:
1. Age when ejaculate contains sufficient spermatozoa to fertilise
FEMALE:
1. Age where female can support a pregnancy without deleterious effects (successful preg and own growth not inhibited)

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2
Q

How does lactation affect cycling?

A
  1. L inhibits GnRH pulse generator
  2. Plasma FSH sufficient to allow follicle development BUT GnRH pulsatility is too low to allow ovulation
  3. Suckling frequency increases inhibition
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3
Q

Is a dairy or beef more likely to come into oestrus sooner and why?

A
  1. Dairy

2. Milked on average 2X a day vs beef milked at higher frequency

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4
Q

How does seasonality affect cycling?

A
  1. seasonality is controlled by GnRH pulse generator
  2. in spring = decreased melatonin which has a different affect on different species: sheep = suppresses pulsitility. Horses = increases
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5
Q

Normal physiological reasons when GnRH pulsatility is suppressed and ovarian cycles stop:

A
  1. Lactation
  2. Photoperiod - (day length) seasonality
  3. Pregnancy
    once animal starts = continues forever
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6
Q

Pathological inputs (physical or mental) to the GnRH pulse generator in animal. Especially what type of animal and why?

A

Type = newly calved dairy heifer as is a Metabolic athlete and:

  1. Stress, being bullied (introduced to herd),
  2. Weight loss (lactating),
  3. Lactating,
  4. Growing
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7
Q

Why can’t you throw hormones at a newly calved dairy heifer that isn’t coming into oestrus?

A
  1. not respond to drugs

2. cause of hypothalamus not firing

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8
Q

List the physiological and pathological reasons for decrease in GnRH pulse frequency

A 
Physiological:
1. Lactation
2. Pregnancy
3. Day length (photoperiod)
Pathological reasons
1. Starvation
2. Stress
3. Disease
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9
Q

Why can’t you throw hormones at a newly calved dairy heifer that isn’t coming into oestrus? What do you have to do instead?

A
  1. not respond to drugs
  2. cause of hypothalamus not firing
  3. have to sort the underlying problem: think “why not coming into oestrus?” bullied = stress? starving? disease?
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10
Q

Outline structure of mammary gland

A
  1. it is a modified sweat gland. Ectoderm epithelial cells

2. Species specific as to how it develops

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11
Q

How does mammary gland develop

A
  1. Modified sweat gland
  2. starts as mammary ridge: ectoderm cells
  3. starts to bud: species specific = diff number of glands, location and structure of teat
  4. Arise from lateral lines on ventral abdomen
  5. diff number of glands
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12
Q

Outline structure of mammary gland

A
  1. Highly organised and vascularised structure external to body cavity
  2. parenchyma = secretary tissue
  3. Milk duct connects to many alveoli which grow into lobules at lactation
  4. alveoli = like bunch of grapes
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13
Q

How does mammary gland develop

A
  1. Modified sweat gland
  2. starts as mammary ridge: ectoderm cells
  3. starts to bud: species specific = diff number of glands, location and structure of teat
  4. Arise from lateral lines on ventral abdomen
  5. Primary buds, then secondary.
  6. Buds then canalised (tube in them)
  7. most development after puberty
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14
Q

Comparative microanatomy of diff species

A
  1. Ruminants = 1 canal
  2. Horse and pig = 2-3 ducts to canal
  3. dogs and cats = multiple canals
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15
Q

What specialises the mammary epithelial cells of alveoli?

A
  1. Highly metabolically active cells on a basement membrane surrounded by collagenous extracellular matrix
  2. loads of rough ER, golgi, smooth ER
  3. milk synthesides across apical surface
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16
Q

What is the major composition of milk

A
  1. protein, fat, lactose

2. differs between sepcies

17
Q

What is the ion composition of milk

A

Na+, K+, Cl-, Ca2+

18
Q

Colostrum

A
  1. prepartum milk secretion
  2. Immunoglobulins produced by plasma cells in gland = passive immunity
    3, short window for absorption
  3. high in fats, proteins, Vit A, low in lactose
19
Q

What is lactogenesis and galactopoesis

A
  1. L = onset of milk secretion

2. GP = continuation of lactation

20
Q

What are the 2 stages of lactogenesis?

A

Stage 1: acquisition of secretory capability PRE PARTURITION
Stage 2: onset of copious secretion at/ around parturition

21
Q

What ensures the synchrony between stage 2 and partuition?

A

HORMONES

  1. inc cortisol (stress) (adrenal gland)
  2. inc prolactin (anterior pituitary)
  3. Inc oestrogen
  4. progesterone plummits = signal of end of gestation
22
Q

What happens when progesterone decreases at teh end of pregnancy?

A
  1. P affects receptors on milk producing cells to prolactin
  2. Prolactin binds
  3. allows synthesis of milk
23
Q

How is milk secretion maintained and what is its name?

A
  1. Galactopoesis
  2. requires hormones:
    a) prolactin = maintain alveolar cell metabolism
    b) oxytocin = remove milk
    c) GH, insulin, thyroid and cortisol all required indirectly
24
Q

How is milk secretion maintained and what is its name?

A

Galactopoesis

  1. requires hormones:
    a) prolactin = maintain alveolar cell metabolism
    b) oxytocin = remove milk from mammory gland + stimulate myoepithelial cells = muscle cells that sit around alveoli
    c) GH, insulin, thyroid and cortisol all required indirectly
  2. REQUIRED removal of milk: feedback inhibitor builds up if not removed
25
Q

Factors that affect milk yield

A
  1. Number of secretory cells in mammary gland
  2. blood supply to mammary gland
  3. Lactose = most important thing affecting volume.
  4. milk removal: suckling/ milking frequency
  5. water intake
26
Q

If an animal has low blood glucose what would happen to the milk produced and why?

A
  1. VOLUME would fall
  2. glucose is substrate for lactose
  3. fall blood glucose = fall in lactose, amount of milk produced = fall
27
Q

How is milk secreted?

A
  1. pushed out by myo epithelial cells (muslce cells) that sit around alveoli
  2. mammary epithelial cells of the alveoli secrete milk into alveolar lumen
28
Q

How does neonate get milk out is there is such a big resistance to flow due to small diameter network

A
  1. stimulates milk ejection reflex in mum

2. Milk PUSHED!

29
Q

Milk ejection

A
  1. Receptors around udder
  2. Brain important: smell and sound
  3. afferent to spinal chord = brain, hypothalamus, posterior pituitary = releases oxytosin in blood = bind to receptors in myoepithalial cells.
  4. neuroendocrine reflex

First year semester 2 (50 decks)

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