Lactation Physiology L19 | Physiology Exam 3

Which embryonic fascia type are mammary gland derived from

ectoderm

What are alveoli and small ducts surrounded by

myoepithelial cells

Which functional unit of the mammary gland responds to oxytocin

myoepithelial cells

What makes up a collection of milk mammary gland lobuli

lobes

What are the functional unit of the mammary gland

alveoli formed by epithelial cells (of the parenchyma)

What is the pathway of milk flow out of the ducts in mammary gland

lactogenesis from alveoli → from lobe → mammary duct → gland cistern → teat cistern → streak canal

Which species has one final milk duct per mammary gland

• cow

• goat

• sheep

Which species has two final milk duct per mammary gland

• mare

• sow

Which species has ten or more final milk duct per mammary gland

• bitches

• queens

Where is milk produced in the udder

alveoli epithelial cells

Where is storage of milk between milkings or suckling occurs

• alveoli

• gland cistern

• teat cistern

Which species has large gland cisterns and teat cisterns

goats

How many mammary glands does goat have

2 mammary glands (1 pair)

How many mammary glands does horse have

2 mammary gland (1 pair)

How many mammary glands does sheep have

2 mammary gland (1 pair)

How many mammary glands does cow have

4 mammary glands (2 pairs)

How many mammary glands does sow have

14-18 mammary glands (7-9 pairs)

How many mammary glands does bitches/queens have

14-20 mammary glands (7-10 pairs)

How many total milk ducts are in a normal, healthy mare

4 milk ducts (1 pair x 2 final ducts =)

How many total milk ducts are in a normal, healthy female cow

4 milk ducts (2 pairs x 1 final duct =)

What is responsible for milk retention in udder of cow

smooth muscle sphincter surrounding teat canal

What is the difference between medial and lateral suspensory ligaments

medial - elastic tissue, originates from linea alba and prepubic tendon

lateral - fibrous tissue, originates from subpubic and prepubic tendon

Which suspensory ligament protects the superficial mammary gland vessels

lateral suspensory ligament

What is the purpose of the suspensory ligaments besides protection

carries weight of udder and milk

What type of tissue is formed by the medial suspensory ligament (and it originates where)

elastic tissue

originates from linea alba and prepubic tendon

What type of tissue is formed by the lateral suspensory ligament (and it originates where)

fibrous tissue

originates from subpubic and prepubic tendons

Which main artery branch supplies blood to udder

external iliac artery

With every liter of milk produced, during lactation, what is the percentage of cardiac output through the udder

10%

Where does venous blood flow along in the udder of cow

along the belly through the milk vein; subcutaneous abdominal vein

Where does lymph flow in the lactating cows

supramammary lymph nodes

What are the two causes of udder edema in prepartum cattle

• tight junctions loosening

• inc pressure in interstitium → occluding lymp vessels

Tight junctions loosening and inc pressure in interstitium causes what in prepartum cattles

udder edema

Udder has what type of innervation

sympathetic innervation

What part of anatomy in lactating cows are important for milk letdown (and why)

skin of teat bc of sensory receptors

When does mammogenesis occur

puberty

What hormones enable proliferation of ducts

• estrogen

• GH

• adrenal steroids

What hormones lead to development of alveoli of mammary gland

• prolactin

• progesterone

• placenta lactogen

During pregnancy of mother, what maternal hormones lead to development of alveoli of mammary gland

• progesterone

• prolactin

What causes lactogenesis to initiate lactation

alveolar cells development and differentiation into milk-producing cells

What is the definition of galactopoiesis

maintenance of lactation

What is the allometric growth of udders of cows

between 3mo-1yr, udder grows 2-4x faster than the rest of the body

During the pre-pubertal period, excessive feeding leads to what in lactating cows

growth of adipose tissue, decline of secretory tissue

With regards to the major hormones affecting mammary gland development, GH is secreted from what endocrine gland and its mammary effect

• anterior pituitary

• stimulates milk production

With regards to the major hormones affecting mammary gland development, Prolactin is secreted from what endocrine gland and its mammary effect

• anterior pituitary

• mammary effect

  • lactogenesis

  • cell differentiation

  • milk protein gene expression

With regards to the major hormones affecting mammary gland development, oxytocin is secreted from what endocrine gland and its mammary effect

• posterior pituitary

• milk ejection reflex

With regards to the major hormones affecting mammary gland development, dopamine prolactin-inhibiting hormone is secreted from what endocrine gland and its mammary effect

hypothalamus

• inhibits PRL secretion

With regards to the major hormones affecting mammary gland development, estrogen is secreted from what endocrine gland and its mammary effect

ovary

• mammary duct growth

With regards to the major hormones affecting mammary gland development, progesterone is secreted from what endocrine gland and its mammary effect

ovary

• mammary lobuloavelor development

• inhibition of lactogenesis

With regards to the major hormones affecting mammary gland development, placenta lactogen is secreted from what endocrine gland and its mammary effect

placenta

• mammary alveoli development

When is udder development more evident (and why is it more evident)

by middle of gestation, prolactin helps form colostrum

What are the main milk components of colostrum

• IgG, IgA, IgM

• vitamin A

• fats

• proteins; casein albumin

What Igs are passed down in colostrum

IgG, IgA, IgM

in ruminants, IgG1 (instead of IgG)

In lactating mare and sows, IgG, IgA, IgM are absorbed extensively and [selectively or non-selectively] in what time period

selectively

in 12-48 hrs

In lactating ruminants, IgG, IgA, IgM are absorbed extensively and [selectively or non-selectively] in what time period

nonselectively

in 12-48 hrs

What hormones stimulates lactogenesis

prolactin

What is the inhibition and stimulation of the release of prolactin

inhibition of prolactin → dopamine

stimulation of prolactin → VIP

What is the physiological pathway of lactogenesis

1. nipple stimulation by suckling

2. afferent fibers to dorsal horn of spinal cord

3. anterolateral columns to brainstem

4. → medial forebrain bundle to synthesize VIP and modulate TIDA neuron activity

5. signals to posterior pituitary to dec dopamine, inc VIP

6. inc prolactin secretion in blood

7. in blood, inc prolactin to alveolar cells of mammary glands

8. cycle starts over again

What is protein composition of milk (physiologically)

• casein

• lactalbumin

• lactoglobulin

• Igs

• enzymes

What is fat composition of milk (physiologically)

• all the glycerides

  • mono-

  • di-

  • tri-

• FFA

• phospholipids

• steroids

What is carbohydrate composition of milk (physiologically)

lactose

Where is most organic components of milk synthesized

in mammary gland

What are the precursors of milk composition (physiologically)

• glucose (→ carbs)

• amino acids (→ proteins)

• fatty acids (→ fat)

What are the precursors of triglycerides in the biosynthesis of milk

• fatty acids derived from diet and adipose tissues

• glucose (in monogastric species) OR VFA (from ruminants)

What two organs assist in chylomicron and VLDL production for biosynthesis of milk in mammary gland

• SI

• liver

What are the percentages of triglycerides synthesis in lactation

• ~50% of FA derived from diet and adipose tissue

• ~50% of de novo synthesis in mammary gland

In ruminant species, what is an important precursor for de novo synthesis of FA

VFA:

• acetate

• butyrate

• ketones

In monogastric species, what is an important precursor for de novo synthesis of FA

glucose

What type of acids are precursors and synthesis of triglycerides in lactating mammary glands

fatty acids

What type of metabolism does glucose undergo for lactogenesis in alveolar cells of mammary glands

phosphorylation

Where and How is lactose synthesized in alveolar cells of mammary glands

in golgi appartus by lactose synthase

How is lactose (primary carbohydrate in milk) synthesized using phosphorylation of glucose (in relation to cell golgi apparatus)

In Alveolar Cell of mammary gland

1 glucose + 1 galactose = [lactose synthase enzyme in golgi apparatus] => lactose

What milk components are secreted by membrane route

• water

• urea

• glucose

• ions

What milk components are secreted by golgi route

• lactose

• casein

• calcium

What milk components are secreted by extrusion

milk fat

What milk components are secreted by transcytosis

Ig

What needs to be performed in order to maintain lactogenesis

milk needs to be continuously removed

Suckling/neuroendocrine can be elicited in what manner

cephalic manner

When are oxytocin levels the highest in lactation process of milking machine

• preparation

• application of teat cups

When does suckling begin in domestic species

1 or 2 hours after birth

When does suckling begin in litter-nursing species (dogs, cats, pigs) species

suckling starts immediately after birth

Which species performs suckling immediately after birth

• pigs

• cats

• dogs

What happens if suckling is delayed

hypoglycemia

How does pregnancy affect milk production

dec milk production

In cows, when is recommended that milking is discontinued

40-60 days after calving (dry period)

After 2 days of last emptying, what occurs to alveolar cells in milking cows

involution of alveolar cells

What is the purpose of bovine somatotropin (rBST)

inc milk production