Slide Set 2: The Mammary Gland Flashcards
1
Q
The mammary gland is composed of
A
☛ Modified sweat gland
☛ Exocrine gland
☛ Accessory gland to the reproductive system
2
Q
What are the major components of the mammary gland iin order:
A
- secretory system
- ductular system
- teats
3
Q
The udder has a complex structure consisting of the following:
A
- The mammary gland (s) components
- A supportive system
- Blood, nerve, and lymph systems
4
Q
How much does the udder weigh?
A
10-25 kg (empty)
5
Q
How many glands does the udder have? and what is the structure like? (4)
A
☛ Four separate simple glands (quarters)
☛ Each gland has one teat & one opening
☛ Right & left halves are entirely separate
☛ Rear quarters are bigger than forequarters
6
Q
Which quarter is bigger in the udder?
A
Rear quarters are bigger than forequarters
7
Q
How is the udder protected?
A
Skin (10-20% of the empty udder) provides protection but little support
8
Q
How is the udder attached to skin? How is the udder attached to the abdominal wall?
A
to skin by fine connective tissue
to abdominal wall by coarse connective tissue
9
Q
What are the two major groups of ligaments of udder?
A
Median Suspensory Ligaments (MSL)
Lateral Suspensory Ligaments (LSL)
10
Q
Where is median suspensory ligament located? What is the structure like?
A
- Arise from the midline of the abdomen and extend between the udder halves
- Divide the udder into two halves (left & right)
11
Q
The median suspensory ligament consists of:
A
Elastic and fibrous connective tissue
12
Q
What are the functions of the median suspensory ligament?
A
☛ Provide the primary support for the udder
☛ Provide elasticity needed by the udder to expand as
it fills with milk
☛ Shock absorption
13
Q
Where is lateral suspensory ligament located? What is the structure like?
A
- Arise from the tendons around the pubic bone
* Extend along both sides of the udder
14
Q
The lateral suspensory ligament consists of:
A
Mostly collagen connective tissue (non-elastic)
15
Q
What are the functions of the lateral suspensory ligament?
A
Provide support to the interior of the udder
16
Q
How many mammary glands does Doe’s udder has and what are the key characteristics? (deer)
A
- Two mammary glands drained by 2 teats
- Size varies considerably
- Teats are wide at the base and protrude like a funnel from the udder
- Teats are covered with fine hair Supernumerary teats are common
17
Q
How many mammary glands does Ewe’s udder has and what are the key characteristics? (sheep)
A
- Two mammary glands drained by 2 teats
- Teats and udder are smaller than in goats
- Gland cisterns are irregular & small
- Teats are covered with fine hair
- Supernumerary teats are common
18
Q
TRUE/FALSE
Gland cisterns of the Ewe’s udder are regular & big
A
FALSE
Gland cisterns are irregular & small
19
Q
How many mammary glands does Sow’s udder has and what are the key characteristics? (pig)
A
- 3-10 pairs of glands (average 6-7 pairs)
- arranged in two parallel row in either side of the ventral median line.
- There are two openings in each teat and each opening is connected to a separate duct and glandular system.
- Teats in front produce milk than the ones at the back
- Supernumerary teats and inverted nipples are common
20
Q
How many mammary glands does Mare’s udder has and what are the key characteristics? (horse)
A
- Two mammary glands each with 2 streak canals (4 glands)
- Teats are flat and broad with blunted tips
- Teats and udder are covered with fine hair and dark pigments
- Sweat and sebaceous glands are present
21
Q
What are the 4 major components of the women mammary gland?
A
1- Lobes
2- milk ducts
3- fat pad
4- connective tissue
22
Q
How many lobes does human mammary gland have? What are their some key characteristics?
A
- There are 15-20 lobes/breast
- Lobes are separated by connective tissue
- Each lobe is drained by its own lactiferous duct leading directly to the nipples
- Number and size of lobes varies between women and breasts
- There are 6-10 large collecting ducts
- Ducts expand slightly beneath the nipple to form sinuses (ampules)
23
Q
Where does milk stay before it gets ejected?
A
ampulla
24
Q
What is areola what are its functions?
A
– Pigmented skin in the center of the breast
– Contains sweat and sebaceous glands
– Contains nerve endings (send suckling signals to the brain)
25
What is nipple what are its functions?
– Terminal point for ducts (lactiferous duct)
– Surrounded by the areola
– During pregnancy, the color becomes darker because of increased pigmentation of the areola and the nipple
26
The core of the nipple is composed of _________
dense connective tissue &elastic fibers smooth muscle cells (circular & longitudinal)
27
The wrinkling of the skin on the nipple results from _________
the attachments of the elastic fibers
28
The contraction of these muscle fibers is responsible for ______ of the nipple.
erection
29
Most of the _________ located around the lactiferous ducts open onto the surface or sides of the nipple open onto the surface.
sebaceous glands
30
Compare the structure of lactating breast and inactive breast
- the main difference is the size of the lobule
- in late pregnancy the size of the breast increases.
- the weight of the breast is 150-200g (non lactating)
- in lactating female the weight of the breast is 500g
- if you make a cross section of the lobule you find a group of
31
What are the components of the mammary tissue? How are they separated?
Lactating
- Parenchyma (lobuloalveolar tissue) ---> ductular and secretory system
```
Non-lactating
- Stroma consists of
•Connective tissue
• Adipose tissue
• Nerve & blood tissue
```
32
What is the function of the connective tissue of mammary gland?
Support the ductular & secretory tissues
33
What is the composition of a desirable connective tissue?
- Minimum connective tissue
| - Maximum secretory & ductular tissue
34
The mammary ductular system starts at the ______ & ends at the ______
alveoli
| streak canal
35
What is the order of the mammary ductular system?
terminal ductule --> mammary duct --> gland cistern --> teat cistern
36
What is the largest structure of the mammary gland?
Lobule
37
The lobule is composed of bunch of alveolar cells. Where does the milk go from the lobule after it is secreted?
they empty the milk into the alveolar duct tube then join each other to form the mammary duct
38
Does the milk composition change once the milk is secreted?
No change in milk occurs once it moves into the duct.
39
Where is the milk stored in between milking? Give examples from mammals
A- Large reservoirs in ruminants (cisterns)
B- Small reservoirs in rats and guinea pigs
C- No reservoirs in rabbits and humans
Cisterns may hold up to 1⁄2 of the milk in the gland
In B& C, most of the milk produced is located in the lobualveolar tissue
40
Where do humans store milk in between milking?
humans don't have cistern and they store the milk within the duct or/and the alveolar system
41
What is the teat structure like in udder?
- 4 teats drain a separate gland
- Fore teats are longer than the rear teats
- void of hair and sweat glands
- most innervated part of the udder
42
_______ contracts around the teat canal to control the ease (speed) of milking
Sphincter muscle
43
How long is the teat canal and what are its key characteristics?
* 7-16 mm long
* 0.08 mm diameter
* Lined with cells that produce bacteriocides
44
What are the key characteristics of teat cistern?
• Milk storage (continuous with gland cistern)
45
What is a lobe?
A group of lobules
46
What is a lobule?
A group of alveoli
47
What is alveoli?
A cluster of alveolus
48
What is alveolus (acinus)?
A single layer of epithelial cells surrounding a central lumen
49
In an ascending order, the secretory tissue is composed of
alveolus
alveoli
lobule
lobe
50
What is the function of the mammary ductular system? What are its structures and key characteristics?
Milk storage in cows
☛ Gland cistern is the largest collection point (400 ml)
☛ Teat cistern holds 30-40 ml of milk
51
What is the function of the myoepithelial cells around the alveoli?
myoepithelial cell surrounds the alveolus
contractile, squeezes the milk from outside
release the milk from the alveoli to the duct system
they have hormonal receptors - oxytocin (most important hormone for milk ejection
52
What is a mammary barrier?
this is a cross section of the alveolar system
| the components that sep the blood and the milk
53
What is myoepithelial cell?
Muscular smooth cell that contracts the alveolus to expel milk into the lumen
54
The basic unit of milk synthesis is ______
Secretory epithelial cell
55
What is the histology of secretory epithelial cell?
Cuboidal shape, lining the alveolar lumen is a single layer
56
What are the major components of secretory epithelial cell?
☛ Nucleus
☛ Endoplasmic reticulum (rough & smooth ER)
☛ Golgi apparatus
☛ Membranes & junctions
57
What are the membranes of the secretory epithelial cells?
- basement membrane
- basal membrane
- apical membrane
58
What is the function of the basement membrane in secretory epithelial cells?
separates stromal & epithelial compartments
59
What is the function of the basal membrane in secretory epithelial cells?
site of milk precursors uptake by the secretory cell
60
What is the function of the apical membrane in secretory epithelial cells?
site of secretion of milk components
61
site of milk precursors uptake by the secretory cell is _________
basal membrane
62
site of secretion of milk components _______
apical membrane
63
What are the types of cell junctions in secretory epithelial cells?
- tight junctions
- gap junctions
- desmosomes
64
What is the functions of the tight junctions in secretory epithelial cells?
seals adjacent cells together & prevent leakage of materials through intercellular spaces
65
What is the function of the gap junctions in secretory epithelial cells?
route for exchange of molecules between adjacent cells
66
What is the function of the desmosomes in secretory epithelial cells?
maintaining cell adhesion
67
What is the function of the Rough Endoplasmic Reticulum in secretory epithelial cells?
Site of protein biosynthesis
68
What is the function of the Smooth Endoplasmic Reticulum in secretory epithelial cells?
Intracellural channels for material transfer
69
What is the function of the golgi apparatus in secretory epithelial cells?
☛ Site of protein packaging (formation of casein micelle) ☛ Site of lactose biosynthesis
70
What is the function of the nucleus in secretory epithelial cells?
contains the genetic materials of the secretory cell
71
What is the function of the secretory vesicles in secretory epithelial cells?
Transport of protein, lactose & salts from the Golgi to the apical membrane
72
What is the function of the cytoplasm in secretory epithelial cells?
☛ Site of fatty acid synthesis
☛ Contains enzymes,
macromolecules & nutrients
73
What are the important arteries that bring oxygenated blood from heart to mammary gland?
1. mammary arteries (external pudic)
2. cranial mammary artery
3. caudal mammary artery
4. aorta
74
Where does external pudic artery feed into?
has two branches for each half of the udder
75
Where does cranial mammary artery feed into?
front side of the udder
76
Where does caudal mammary artery feed into?
rear part of the udder
77
What are the two veins that collect blood from the udder?
1. external pudendal vein
| 2. subcutaneous vein (milk vein)
78
What are the veins that bring the blood back to the heart?
1. vena cava
2. external iliac
3. external pudic
4. subcutanous abdominal vein
79
How is the teat controlled by the nervous system?
two types of control
1. autonomic (involuntary) divides into sympathetic and parasympathetic
2. somatic (voluntary)
80
The nervous system in the teat is responsible for:
1. milk ejection
| 2. milk inhibition
81
How does the nervous system control milk ejection?
The highest innervation in all mammary gland there is nerve ending on the teat and the young will suckle and the signals will be sent to the brain to secrete oxytocin. oxytocin will bind to the myoepithelial cell and that will start the contraction of the myeoepithelial tissue
82
Milk ejection has two components:
1. ________
2. ________
and the collective name for this is ________
- neural
- hormonal
NEUROHORMONAL REFLEX
83
How does the nervous system control milk inhibition?
milk inhibition is caused by the sympathetic nervous system
that nervous system is activated during stress under stress
VASOCONSTRICTION
less flow to the mammary gland which means less milk. it happens to most of the mammalian species
dairy cows its a big problem. cow comfort which means you need to make the cow happy to avoid stress
happy cows mean more milk
84
How is the nervous system of the mammary gland innervated?
- Innervation of the udder is sparse
- No direct innervation of the secretory cell
- No parasympathetic innervation
- Neural receptors (somatic NS) are present in the skin of the teats and udder (greatest innervation is in the teat)
- Sympathetic innervation is associated with arteries
85
______ nervous system controls blood flow to the udder
Sympathetic
86
______ innervation is associated with arteries
Sympathetic
87
Neural receptors (_____ NS) are present in the skin of the teats and udder (greatest innervation is in the teat)
somatic
88
Stimulation of the sympathetic nervous system (e.g. stress) causes:
- vasoconstriction of blood vessels
- reduces blood supply to the mammary gland
- reduction in milk yield
89
How is the lymphatic system of the mammary gland structured?
- Lymph vessels carry tissue fluid (lymph)from tissue spaces to lymph nodes
- Lymph nodes filter the tissue fluids to remove foreign materials
- thoracic duct
- veins
90
What are the main functions of the lymphatic system in the mammary gland?
- Carries waste products away from active cells
- Carries chylomicrons
- Carries immune bodies from lymph nodes
- Carries co-aggulating proteins
- Dissipate heat from cells
91
Lymph vessels travel in a ______ direction to the _______ lymph node
dorsal-caudal
| supramammary
92
Lymph moves only in one direction toward the ______
Supramammary lymph node
93
How is the lymphatic system of the mammary gland of dairy cows structured?
✰ Dairy cows have two supra-mammary lymph node (one on top of each half of the udder
✰ Valves in lymph vessels cause lymph to move only in one direction
✰ Subcutaneous lymph vessels are very prominent in mature cows
✰ Accumulation of excessive fluid in subcutaneous lymph vessels may cause udder edema (accumulation of fluid between udder skin and secretory tissues)
94
What happens when lymph fluid accumulated in the lymph vessels?
Accumulation of excessive fluid in subcutaneous lymph vessels may cause udder edema (accumulation of fluid between udder skin and secretory tissues)
95
Where does the lymphatic fluid drain in women's breast?
- Lymph drains from superficial to deep space and most lymph exits through retro-mammary space at the rear of the breast
- Central & lateral parts of the mammary gland (~75%) drain into the axillary lymph nodes
- 20% drains into internal mammary lymph nodes (inner & outer parts of the breast)
96
Central & lateral parts of the mammary gland (~75%) drain into the ______
axillary lymph nodes
97
20% drains into _______ (inner & outer parts of the breast)
internal mammary lymph nodes
98
Lymph drains from _________ space and most lymph exits through __________ at the rear of the breast
superficial to deep
| retro-mammary space
