5. Glands Flashcards
(177 cards)
1
Q
Define a gland
A
An epithelial cell or an aggregate of epithelial cells that are specialised for the secretion of a substance
2
Q
Define secretion
A
The production and release of materials by a cell or aggregate of cells
3
Q
List 3 things that glands receive stimulus from
A
- Brain(CNS)
- Chemicals
- Neighbouring cells
4
Q
What is usually considered to classify glands?
A
- their structure
2. how their products are released
5
Q
What do mucous and goblet cells both secrete
A
Mucin - protein which mixes with water to produce mucus
6
Q
What is the main difference between exocrine and endocrine glands?
A
Exocrine glands are ducted - secrete into a location through a duct
Endocrine glands are ductless - secrete directly into blood
7
Q
What do endocrine glands secrete?
A
Hormones
8
Q
What do exocrine glands secrete?
A
Enzymes or lubricants
9
Q
Give 3 examples of endocrine glands
A
- Pituitary gland
- Thyroid gland
- Parathyroid gland
10
Q
List 3 secretions of the anterior pituitary gland
A
- Hormones that regulate most of the glands of the endocrine system e.g LH,FSH,TSH,ACTH
- Prolactin - milk
- Somatotrophin - growth
11
Q
List 2 hormones secreted by posterior pituitary gland
A
- vasopressin
2. oxytoxin
12
Q
What is the function of the thyroid gland?
A
Produces thyroid hormones T3 & T4 that control metabolism;
calcitonin, involved in calcium homeostasis
13
Q
What is the function of the parathyroid gland?
A
Produces parathyroid hormone, calcium
homeostasis
14
Q
Which epithelial cells of the endocrine gland secrete the hormone?
A
ALL epithelial cells
15
Q
Give 6 examples of exocrine glands
A
- salivary glands
- Pancreas
- mammary
- sweat glands
- sebaceous gland
- Lachrymal gland
16
Q
Where are sebaceous glands found and what do they secrete?
A
Attached to hair follicle. Secretes sebum onto the skin and in the ear (contributes to earwax) to protect these tissues from pathogens. Lubricate the shaft of the hair for growth and waterproof the skin
17
Q
Where are Lachrymal glands found and what do they secrete?
A
In eye secrete water to moisten the eye, also produce lysozyme (an enzyme to attack bacteria).
18
Q
Which epithelial cells of the exocrine glands secrete the products?
A
only cells at the apex of the duct
19
Q
What do mammary glands produce?
A
Produces colostrum and milk in response to prolactin and oxytocin (hormones) to nourish neonates
20
Q
Explain the generation of exocrine glands
A
- Growth signal received
- Proliferation of [daughter] cells occurs and extracellular protein degradation enzymes produced
- Epithelial cells invade space created
- Central cells die off to produce duct
(canalicularisation) . - Apical cells differentiate to produce specific secretory products
21
Q
Explain the generation of endocrine glands
A
- Growth signal received
- Proliferation of [daughter] cells occurs and extracellular protein degradation enzymes produced
- Epithelial cells invade space created
- produce angiogenic factors to
stimulate blood vessel growth in and around the epithelial cells - Link to [mother] cells broken through apoptosis
22
Q
In thyroid follicles, what causes expansion of the follicle into a sphere?
A
Production of colloid between epithelial cells
23
Q
What do some of the cells at the secretory ends of exocrine ducts change into and why?
A
myoepithelial cells
: - Cells that have features of both an epithelial cell and a smooth muscle cell
- Help to eject secretions from the duct
24
Q
What are the two types of secretions
A
- Mucous
2. Serous
25
What are the 3 types of glandular secretions?
1. Merocrine
2. apocrine
3. Holocrine
4. Cytocrine
26
What is merocrine secretion?
fusion of vesicles containing secretory substance with apical membrane to release it out of the cell
- A form of exocytosis
27
What is apocrine secretion?
partial loss of cytoplasm containing secretory substance
28
What is holocrine secretion ?
complete loss of cytoplasm or cell
29
Give examples of merocrine glands
Acinar and endocrine glands of the pancreas
30
Give examples of apocrine glands
Lactating mammary gland, sweat glands in the axila and external genitalia
31
Give examples of holocrine glands
Sebaceous gland in skin and tarsal glands in eyelid
32
What is Cytocrine secretion?
cells are released as a secretion
33
Give an example of a Cytocrine gland
Spermatid
34
What are the two pathways of merocrine secretion?
1. Regulated secretion
| 2. Constitutive secretion
35
What happens in regulated secretion?
Secretory granules accumulate in large vesicles and are released by exocytosis upon stimulation - need calcium ions to work
36
What happens in constitutive secretion?
The secretory product is not concentrated into granules but packaged into small vesicles and continuously released to the cells surface
Used mainly to repopulate the plasma membrane with plasma proteins
37
Describe the process of regulated merocrine secretion
Active process – uses energy
1. Contents of vesicle (cargo) can be anything within the cell
2. Active secretion requires specific signal (Ca2+ ions)
3. Vesicle migrates to cell surface along microtubules
4. In presence of Ca2+ ions, membrane of vesicle fuses with plasmalemma
5. Cargo released to extracellular space
38
In the neonatal period, are both fats and milk proteins secreted by apocrine secretion in the breast?
No, Only fats are secreted by apocrine secretion (signet fragment)
Milk proteins made in RER and on free ribososomes are packed into
vesicles produced by the Golgi
apparatus
- released by merocrine secretion
39
During lactation, are fats and milk proteins both secreted by apocrine secretion in the breast?
Yes,
both fats and
proteins are released by apocrine
secretion
40
Describe holocrine secretion using th sebaceous gland as an example.
1. The secretory cell gradually fills up with
secretory granules
2. The cell organelles degenerate
3. The cells die
4. The plasma membrane breaks and the contents (secretum) (sebum) empties
5. Dead cells are replaced by mitotic division of the basal cells
41
What is the structure of the Golgi apparatus?
>Stack of disc-shaped cisternae
>One end of discs are flattened (trans), the other concave(cis)
>Discs have swellings at their edges
>Distal swellings pinch off as migratory Golgi Vacuoles
42
What is the function of the Golgi apparatus?
> Transport through the sequential Golgi apparatus cisternae >Packaging of sorted contents through condensation
>Adding sugars to proteins and lipids (Glycosylation)
43
What are the Golgi product destinations?
.Majority extruded in secretory vesicles
>Some retained for use in the cell (e.g. lysosomes)
>Some enters the plasma membrane (glycocalyx*) *GLYCOCALX = Sweet husk
44
Define glycosylation of proteins
The covalent attachment of sugars by enzymes to proteins and lipids to form glycoproteins and glycolipids
45
Define glycation
formation of glycoproteins withoute enzymes
46
What re the 5 roles of glycosylation?
1. To aid protein folding
2. Prevents protein digestion by intracellular proteases
3. Prevents lipid digestion by intracellular lipases
4. Cell recognition (blood groups)
5. Role on cell to extracellular matrix attachment
47
Define exocytosis
Secretion of molecules outside the cell via a vesicle fuming to a membrane
48
Define endocytosis
Engulfing of molecules inside the cell via vesicle formation
49
Define phagocytosis
Phagocytosis is the process by which cells (phagocytes), envelop or engulf other cells or particles
50
Define pinocytosis
pinocytosis is the process in which liquid droplets are ingested by cells.
51
Which cells use pinocytosis?
Pinocytosis used by all cells, especially smooth muscle cells
52
What is paracellular transport?
When molecules move through an aqueous channel n the intercellular junction
53
What is transcellelar transport?
When molecules move though lipid cell membranes
54
How do impermeable substances pass through an epithelial membrane?
Those that are impermeable may bind to cell surface receptors, be engulfed by the cell membrane (endocytosis) and then released inside the cell or expelled via membrane-limited vesicles out of the cell and into the extracellular space (exocytosis)
55
List the 3 types of glandular control
1. humoral stimulus
2. neural stimulus
3. Hormonal stimulus
56
Which glands use humoral stimulus?
Humoral stimulus through feedback loops most prevalent in endocrine glands
57
Which glands use hormonal stimulus?
Hormonal stimulus most prevalent in
| endocrine glands
58
Which glands use neural stimulus?
Neural stimulus solely controls
| salivary (exocrine) gland secretion
59
How are gland secretions controlled?
By negative feedback mechanism
60
What is neurocrine communication?
I don’t know
61
List the 3 type of hormones
1. Peptide hormone
2. Steroid hormones
3. Amino acid derived hormones - catecholamines
- thyroid hormones
62
Give examples of what hypothalamus deal with
```
—Thermoregulation
– Plasma osmolality via osmoreceptors
– Heart rate, blood pressure
– Feeding, satiety, regulation of the gastrointestinal tract
– Circadian rhythms, wakefulness, sleep
– Stimuli from the autonomic nervous system (both sympathetic and parasympathetic)
– Emotion, sexual behaviour, mood
– Lactation (suckling/baby crying)
```
63
How are portal circulatory systems different to the typical circulatory system?
In typical circulatory route, blood flows from the arteries to capillaries to veins.
In portal systems, blood flows from the armies to capillaries and then to portal vessels/veins and then to capillaries again and then to vein. There are two sets of capillaries instead of 1
64
What is the name of the portal blood supply to the anterior pituitary ?
Hypothalamus-hypophyseal portal system
65
At which week of gestation do endocrine glands form?
From week 5 onwards
66
Describe the structure and location of the thyroid gland
The thyroid gland consists of two almost spherical lobes joined together by a small connecting piece called the isthmus and is positioned low in the anterior surface of the neck. The isthmus lies just under (inferior to) the cricoid cartilage in the neck with thyroid lobes lying on either side of the trachea and away from the midline (more lateral).
Third or fourth cartilage down
67
What stimulates the production of the thyroid hormones T3 and T4/
1. Thyroid stimulating hormone (TSH) released by the pituitary gland
2. Thyroid stimulating antibodies (TSAbs)
68
What does high levels of T3 and T4 indicate and how does the body deal with it?
Indicates hyperthyroidism and so pituitary glands secrete less TSH so less stimulation of thyroid to make hormones
69
What does really low levels of T3 and T4 indicate and how does the body deal with it?
Indicates hypothyroidism and causes pituitary gland to secret more TSH. So more stimulation of thyroid gland
70
What are parafollicular cells?
Neuroendocrine cells that migrate into the thyroid during thyroid development in the embryo and produce the peptide hormone thyrocalcitonin/calcitonin
71
What is the role of parafollicular cells?
to monitor plasma calcium concentrations and decreases the levels (counteracts the function of PTH)
72
What is the major effect of parafollicular cells?
inhibits osteoclast activity in bone
73
What is the minor effect of parafollicular cells?
inhibits renal calcium and phosphate re-absorption in the tubular cells; more calcium and
phosphate excreted
74
What is an autoimmune disease?
An autoimmune disease is a condition in which your immune system mistakenly attacks your body’s own cells as it can’t recognise the cell’s antigen. Immune system release antibodies against own specific cells which destroy the cells eg by apoptosis.
75
Give 5 examples of autoimmune diseases
multiple sclerosis, psoriasis, Rheumatoid arthritis, inflammatory bowel disease, type 2 diabetes
76
Give two examples of autoimmune disorders that affect the endocrine system.
Hashimoto’s thyroiditis
| Grave’s disease
77
What is hashimoto’s thyroiditis?
Hypothyroidism
78
What is Graves’ disease?
Hyperthyroidism
79
In the case of autoimmune hypothyroidism(Hashimoto’s), what antibodies present in the blood can we detect and measure?
Thyroid peroxidase
Thyroid globulin
TSH receptor blocking antibodies
80
In the case of autoimmune hyperthyroidism(Grave’s), What does one of the circulating antibodies mimic and thereby cause hyperthyroidism?
Thyroid stimulating immunoglobulin(antibody) Mimic TSH so bind to TSH receptors on thyroid and stimulate thyroid to release more T3 and T4 hormone so normal TSH levels decrease due to negative feedback but wont have an effect because antibodies are still there so cannot be controlled.
81
What are the features of Gave’s disease (hyperthyroidism)?
Symptoms;
high thyroid hormone - metabolism higher so weight loss, heat intolerance(really hot)
Features:
• Goiter- swelling on neck due to overactive thyroid - can happen in both hyper and hypo but classically in hyper
• Bulging eyes - exothalmos - ophthalmopathy
• Skin - red swollen - pretibial myxedema
82
What is the role of the parathyroid gland?
Constantly monitor plasma calcium concentrations
83
Describe the function of the parathyroid gland
1. Plasma calcium is low, then parathyroids make parathyroid hormone (PTH)
2. PTH causes the bones to release calcium into the blood and absorb more
from the GIT
3.Classical negative feedback loop (calcium reaches set point; parathyroid glands STOP making PTH
84
Why does parathyroid disease (over-production of PTH from a parathyroid
tumour leading to high blood calcium) causes symptoms of the brain,
muscles, and bones?
Calcium is the most important element for the nervous system, the muscular system, and the skeletal system.
• Calcium provides the electrical system for our nerves, and muscles, allowing the nerves to conduct electricity and the muscles to contract
85
Where are the adrenal glands found and what are their shapes?
The adrenal glands are found on top of the kidneys. The right and left adrenal glands have inferential shapes. The left adrenal gland is a crescent moon shape and right adrenal gland is pyramid shape
86
What is the adrenal medulla composed of ?
parenchyma of large,
| pale-staining epithelioid cells called chromaffin cells - modified neurons
87
Numerous myelinated, presynaptic sympathetic nerve
| fibres pass directly to the chromaffin cells. What happens when a nerve impulse reaches the chromaffin cells?
When nerve impulses reach the catecholamine-secreting chromaffin cells, they release their secretory products catecholamines. Examples of catecholamines include dopamine; norepinephrine(noradrenaline); and epinephrine (adrenaline)
88
What are chromaffin cells considered equivalent to?
postsynaptic neurons
89
Describe the three layer of the adrenal cortex and the hormones made in each layer.
Outer – Zona glomerulosa
Aldosterone regulates BP
Middle – Zona fasciculata
Glucocorticoids (cortisone/cortisol) mobilises fats, proteins and carbohydrates (but not during fasting/starvation)
Inner – Zona reticularis
Androgen precursors i.e. androstenedione, DHEA, etc.
90
What is the main function of all the hormones released by the adrenal gland
Stress response
91
Define stress
state of real or perceived threat to homeostasis
92
Define stress response
Maintenance of homeostasis in the presence of aversive stimuli (stressors) [that] requires
activation of a complex range of responses involving the endocrine, nervous and immune
systems
93
What are the behavioural changes that occur during the stress response?
* increased awareness
* improved cognition
* euphoria
* enhanced analgesia
94
What are the physiological changes that occur during the stress response?
* Increased cardiovascular tone
* Increased respiratory rate
* Increased intermediate metabolism
Decreased vegetative functions such as feeding, digestion, growth, reproduction, and immunity
95
What are the adrenal cortical hormones?
glucocorticoids (cortisol) and mineralocorticoids (aldosterone)
96
Where are the principal effectors of the stress response localised?
hypothalamus, the anterior lobe of the pituitary gland, and the adrenal gland
97
Describe the pathway to bring about the response to short term stress
Short term stress detected in the hypothalamus which sends a nerve impulse to the CNS which send another nerve impulse to the adrenal medulla which release catecholamines which bring about the response
98
What is the short term stress response?
1. Increased heart rate
2. Increased BP
3. Glycogen converted to glucose in liver and released to blood
4. Dilation of bronchioles
5. Changes in blood flow patterns leading to increased alertness, decreased digestive system activity and reduced urine output
6. Increased metabolic rate
99
Describe the pathway to bring about the response to long term stress
Long term stress detected by the hypothalamus which secretes corticotrophin releasing hormone(CRH) which causes the anterior pituitary gland to secrete ACTH which travels to the adrenal cortex via the blood and causes the release of mineralcorticoids and glucocorticoids which bring about the long term stress response
100
What is the long term stress response?
1. Retention of sodium and water by kidneys
2. Increased blood volume and BP
3. Proteins and fats converted to glucose or broken down for energy
4. Increased blood sugar
5. Suppression of immune system
101
Does the pancreas contain endocrine or exocrine glands?
Both
102
What are the acinar glands of the pancreas grouped into?
Lobules
103
What are the lobes in the pancreas lobules hold together by?
Connective tissue
104
What do the pancreas lobules contain?
Numerous zymogen granules
105
Where are the zymogen granules released into?
```
through numerous
intercalated ducts to
pancreatic duct
• Which joins with bile duct to
make common bile duct
```
106
How can the islet of langerhan be identified in a stained sample?
Lighter in colour than rets
107
What does the exocrine function (acini) produce?
```
Produces:
• Trypsinogen (converted to trypsin)
• Chymotrypsinogen (converted to chymotrypsin)
• Lipase
• Amylase
• Ribonuclease
• Deoxyribonuclease
• Gelatinase
• Elastase
```
108
What are the endocrine functions(islet of langerhan)?
1.α cell – Glucagon (catabolises glycogen to glucose)
.β cell - Insulin (uptake and storage of glucose)
3.δ cell – Somatostatin (inhibits insulin and glucagon secretion)
4.PP cell - Pancreatic polypeptide (inhibits bile, pancreatic enzyme and bicarbonate secretion) 5.D-1 cell – Vasoactive intestinal peptide (similar to glucagon, stimulates enzymatic secretion and gut motility)
109
What are the 3 exocrine salivary glands?
1. Parotid gland
2. submandibular gland
3. sublingual gland
110
Are parotid glands serous or mucous?
Almost totally serous but do have a small amount of mucous cells - so produces both serous and mucous fluids
111
Are submandibular glands serous or mucous?
Mostly serous but more mucous than parotid
112
Are sublingual glands serous or mucus?
Almost completely mucous
113
How can you identify serous glands from mucous glands in specimen?
Serous - closed and cannot see lumen very well, dark staining. possess granular cytoplasm and nuclei which are spherical and vesicular in appearance
Mucous - pale staining cytoplasm and nuclei which appear to be pushed against the basal cell membrane
114
What are zymogen granules
Specialised storage organelles which allow the sorting,packaging and secretion of digestive enzymes
115
Where in the parotid glands are zymogen granules found?
Serous cells
116
Where are the parotid glands?
Next to the ear
117
Where are the submandibular glands found?
Underneath the mandible
118
When are submandibular glands palpated?
When someone has an oral infection
119
What are the two parts that the submandibular gland is split into?
Superficial surface and internal surface
120
What is the superficial surface and internal surface separated by in the submandibular gland?
Mylohoid muscle
121
Does the submandibular surface contain mucous acini or serous acini?
Mucous acini
122
Does the internal layer contain mucus or serous acini?
Serous
123
What is the name of the duct that connects the submandibular glad to sublingual gland and has its outlet underneath the tongue?
Wharton’s duct
124
Where does the parotid duct discharge?
High up in the oval cavity
125
How are he salivary glands stimulated?
By the autonomic nervous system only
126
Are the salivary glands controlled by parasympathetic or sympathetic nervous system?
Both
127
What is the function of the parasympathetic NS in salivary secretion?
Produces a large volume of watery saliva rich in enzymes - serous cells
128
What is the purpose of the sympathetic NS in salivary secretion?
Produces small, thick secretion of saliva rich in mucus - mucous gland cells are controlled by sympathetic
129
How do you remember which cells are controlled by sympathetic and parasympathetic?
Sympathetic - flight or fight - mouth drys up, sweat more - SSS
130
What is the largest exocrine gland in the body?
Liver
131
Where is the pancreas?
On the right hand side underneath the rib cage
132
How many parts is the liver divided into?
Two
133
Which part of the liver can regenerate in a year?
Left lobe
134
What are the two sources of blood supply to the liver?
1. Hepatic portal vein
| 2. Hepatic artery
135
give an overview of the hepatic portal system
1. Blood from the artery is passed into a set of capillaries in the stomach and small intestines.
2. Nutrients and toxins are absorbed into the blood which passes into the hepatic portal vein.
3. The blood then passes into a second set of capillaries in the liver where nutrients and toxins leave the blood.
4. The blood then passes into the hepatic vein and then back to the heart through the inferior vena cava
136
How and why is the structure of the capillary bed in the stomach and small intestines different to the capillary beds in the liver?
Capillary bed in the stomach and small intestines is much smaller than the capillary beds in the liver. This is because the capillary beds in the liver are not really capillaries but specialised tubes called sinusoids which which makes the vessels larger than normal.
137
Describe the blood supply from the hepatic artery
Blood from the aorta travels straight into the hepatic artery which flows into the liver. - oxygenated blood
138
Describe the blood supply to the liver is the hepatic portal vein
1. Oxygenated blood from the aorta pass into the spleen which interacts with the reticular sites inside the spleen.
2. The blood comes back out through the splenic vein
3. Which meets with blood coming from the inferior mesenteric vein(blood from the large intestines)
4. Which also joins with blood from the superior mesenteric vein(blood from the stomach and small intestines)
5. All these join to make the portal vein which takes the deoxygenated blood t the liver.
139
How much blood reaching the liver is oxygenated (from hepatic artery) and how much is deoxygenated (from hepatic portal vein) ?
About 25-30% is oxygenated and 70-75% is deoxygenated
140
Where does the blood enter into in the liver?
Lobule
141
What is a lobule?
The basic functional units of the liver
142
What are hepatocytes?
Liver cells
143
What happens to the blood reaching the lobules from the hepatic artery and portal vein?
They mix in the sinusoids (not capillaries )
144
Describe fully what happens inside the lobules
1. After the blood from the hepatic artery and portal vein has mixed. As the blood flows through the sinusoids, hepatocytes absorb solutes from the plasma and oxygen from RBC and secret materials such as plasma proteins into the blood.
2. The blood then leaves the sinusoids and enters the central vein of the lobule
3. The central veins eventually merge to form the hepatic vein which then empties into the vena cava.
145
What is the name of the passageway that connect the central vein to the bile duct?
Bile canaliculi
146
What vessels are included in the portal triad of the liver?
1. Hepatic artery
2. Portal vein
3. Bile duct
147
What are the 3 types of vessels?
1. Continuous
2. Fenestrated
3. sinusoids
148
Where are continuous vessels found?
Brain/most of the body
149
Where are fenestrated vessels found?
Pituitary/ small intestine / Kidneys/ some endocrine glands
150
Where are sinusoid vessels found?
Spleen/ bone marrow / Liver/ lymph nodes
151
Why do fenestrated vessels contain fenestrations?
The fenestrations(gaps) help to get substances (fluids, electrolytes, proteins) through the capillary endothelium fast into the tissue
152
What makes sinusoids different and why?
They have an incomplete basement membrane and big gaps in the endothelium layer so large substances, even cells can get through the gaps. Very useful in organs where cells are produced and need to pass the cells into the the bloodstream
153
Why are H&E staining of liver lobules very red?
Because eosin stains proteins red and the liver cells are making huge amount of protein
154
What is the general shape of a liver lobule?
Hexagonal - though may sometimes differ
155
How many separate portal triads may be found on a lobule usually?
6
156
How many nuclei do hepatocytes usually contain?
2 or 3 nuclei
157
How can you identify the portal vein from the bile duct and hepatic artery in a histology picture?
The portal vein is much larger than the other two
158
What type of cell is a hepatocyte?
Epithelial
159
What is the white space between the portal vein and hepatic artery in the liver filled with?
Fat - not adipose tissue but triglycerides and cholesterol because one of the functions of the liver is to process cholesterol
160
Why do hepatocytes have more than one nucleus?
Because hepatocytes need to make a lot of protein so need to make lot of mRNA
161
List2 cells found in the sinusoid lumen
1. Kuppfer cells
| 2. Pit cells
162
What is the space of disse?
The space between the endothelial layer of the sinusoid and hepatocytes
163
List two cells found in the space of disse
1. Dendritic cell
| 2. Stellate cell
164
What is the function of the dendritic cell?
Exact function in liver not known but considering function in other parts of the body, it can be used that its function is to grab hold of pathogens and act as antigen presenting cells which present the antigens to T cells.
165
What is the function of pit cells?
To identify cancer cells that enter the sinusoids and destroy them-called natural killer cells
166
How are hepatocytes different from other epithelial cells?
1. Epithelial cells have a basal surface and a apical surface opposite.
But hepatocytes have two apical surfaces instead of 1 basal surface.
2. In normal Epithelial cells, specialises like microvilli sit on the apical surface. But, in hepatocytes, specialisations like microvilli sit on the basolateral surface
167
What are kupffer cells?
Specialist macrophages that form part of the sinusoidal lining
168
What is the function of Kupffer cells?
1. Trap and phagocytose any damaged or aged erythrocytes
that were missed by the spleen
2. Ingest pathogens
3. After splenectomy, these cells take over the removal of 120
day old (aged) erythrocytes
169
What are kupffer cells constantly exposed to?
gut-derived bacteria, microbial
| debris, cell debris and bacterial endotoxins
170
Why are the vessels in the liver being perforated with large holes useful?
Allow Kupffer cells to migrate into liver tissue at sites of inflammation and damage
171
What is the function of stellate cells?
Take up vitamin A and coalesce the vitamin A into lipid droplets that is then stored
172
What happens to stellate cells in liver cirrhosis?
hepatic stellate cells lose
their vitamin A storage
capability and differentiate into myofibroblasts(both muscle cell and fibroblast).
These synthesise and deposit collagen within the perisinusoidal space, resulting in liver fibrosis
173
What are the 4 functions of the liver?
1. Storage
2. Anabolism(production)
3. catabolism(destruction)
4. Other functions
174
What does the liver store:
```
• Iron
• Vitamins A, B12, D and K
o Lipid soluble vitamins
• Glycogen
• Copper
```
175
Give examples of anabolism in the liver
```
More than 60% of all the body’s proteins
• Major plasma proteins
>Albumin
• Enzymes
> Catalase and coagulation factors • Lipid carrier proteins
>Apolipoproteins (HDL, LDL, etc)
• Amino acid synthesis
• Haemopoiesis in the fetus (from week 5 to week 32)
```
176
Give examples of catabolism in the liver
• Drugs
• Hormones
>Steroids, insulin, glucagon, etc
• Haemaglobin
> Bilirubin passed to gall bladder
• Poisons/toxins
• After splenectomy – removal of
RBCs
177
What are the other functions of the liver?
```
• Bile production (exocrine)
• Filtering of cell debris from blood
• Hormones/Growth factors
(endocrine)
>Angiotensinogen, Thrombopioetin and IGF-1
• Modifies hormones for excretion or
function
>Oestrogen, progesterone
```
>Thyroxine to T3, Vitamin D3 to calcitriol
