Lecture 8 - Enodcrine Tissues And Glands Flashcards
Name some examples of glands containing endocrine cells/tissue:
Hypothalamus
Pituitary gland
Thyroid gland
Parathyroid gland
Adrenal gland
Pancreas
Where is the pituitary gland located?
At the base of the brain superior to the hypothalamus
What hormones does the Hypothalamus secrete?
TRH
CRH
GHRH
GHIH
PRH
GnRH
How is the pituitary gland structure?
Into 2 parts:
Anterior pituitary (front)
Posteriori pituitary (back)
What hormones does the anterior pituitary gland secrete?
TSH
ACTH and MSH (Both have POMC precursor)
FSH
LH
Prolactin
GH
Where is the Thyroid gland located and how is it structured?
Anterior to the trachea
2 lobes joined by a bridge called the Isthmus
What hormones does the thyroid gland secrete?
T4 (thyroxine or tetraiodothyronine)
T3 (triiodothyronine)
Where are the parathyroid glands located?
On the dorsal surface of the thyroid glands
4 of them in 2 pairs
What do the parathyroid glands secrete?
PTH (parathyroid hormone)
Where are the adrenal glands located?
On the top of the kidneys
Ad = on top of
Renal = kidneys
How are the adrenal glands structured?
2 parts
Outer adrenal cortex
Inner adrenal medulla
What hormones does the adrenal cortex secrete?
Mineralocorticoids
Glucocorticoids
Androgens
Where is the pancreas located?
Left of and posterior to the stomach
What are the exocrine secretions of the pancreas?
Digestive enzymes into duodenum
What are the secretions from the endocrine portions of the pancreas and what are these portions called?
Islets of Langerhans
Alpha cells = glucagon
Beta cells = insulin
Delta cells = somatostatin
What hormones does the posterior pituitary gland secrete but not produce?
ADH (anti-diuretic hormone)
Oxytocin
What hormones dos the liver produce?
IGF (Insulin like growth factor)
Angiotensinogen
Angiotensin (increases blood pressure)
Thrombopoietin
What hormones does the kidney produce?
Erythropoietin
Thrombopoietin
Renin
Calcitriol
What are the 4 main types of hormones?
Peptide and Glycoprotein hormones
Steroid hormones
Amino-acid derived hormones
Lipid hormones
How are Peptide hormones and glycoproteins synthesised and stored?
Made in advance
Stored in secretory vesicles
How are Peptide hormones and glycoproteins transported in the blood?
Dissolved in plasma
Where are the receptors for Peptide hormones and glycoproteins?
Plasma membrane of cells
(Water soluble)
How do Peptide hormones and glycoproteins affect cells?
Activate a second messenger system
Activates gene expression
Give some examples of Peptide hormones and glycoproteins:
Insulin
Glucagon
Prolactin
ACTH
PTH
Gastrin
How are steroid hormones synthesised and stored?
They are not stored
Synthesised on demand
How are steroid hormones transported in the blood?
Bound to carrier proteins
Where the receptors for steroid hormones?
Mainly in the cytoplasm or nucleus of a cell
(Lipid soluble so can cross cell membrane)
How do steroid hormones affect cells?
Activate genes for transcription and translation
Normally bind to receptors Ono a region of DNA called Hormone Response Elements (HREs)
Give some examples of steroid hormones:
Oestrogen
Progesterone
Cortisol
Glucocorticoids
Mineralocorticoids
How are amino acid-derived hormones synthesised and stored?
Synthesised in advance and stored in secretory vesicles
What are the 2 types of Amino acid-derived hormones?
Catecholamines
Thyroid hormones
How are Catecholamines transported in the blood?
Dissolved in the plasma
Where are the receptors for Catecholamines?
Cell membrane
How do Catecholamines affect cells?
Activate second messenger systems which affect gene expression
Give some examples of Catecholamines and where are they produced?
Adrenal Medulla
Adrenaline
Noradrenaline
Dopamine
How are Thyroid Hormones transported in the blood?
Bound to carrier proteins
Thyroxine binding globulin
Where are Thyroid Hormones receptors found?
In the nucleus
How do Thyroid Hormones affect cells?
Activates genes for transcription and translation
What are the 2 thyroid hormones?
T3
T4
How are lipid hormones synthesised and stored?
Synthesised on demand
NOT STORED
How are lipid hormones transported in the blood?
Dissolved in plasma
AND
Bound to carrier proteins
Where are the receptors for lipid hormones?
Cell membrane
How do lipid hormones exert there affects on cells?
Activates second messenger systems which affect gene expression
Give some examples of lipid hormones:
Thromboxanes
Prostaglandins
Endocannabinoids
What strucutre connects the hypothalamus to the pituitary gland?
Pituitary stalk (infundibulum)
Which gland is central to homeostasis?
Hypothalamus
How does blood travel through a portal system?
Travels through 2 sets of capillaries before returning to the heart
Blood from first set of capillaries collects in portal vessels which then branch into another capilary network in another location before returning back to veins to the heart
How is the Hypothalamo-hypophyseal portal system structured?
First capilary network in hypothalamus
Then second capillary network in anterior pituitary
What type of secretion occurs in the hypothalamus and pituitary?
Merocrine secretion
Both regulated and constitutive
In Graves’ disease what type of autoantibodies are acting and what do they cause?
Thyroid Stimulating Immunoglobulins
Bind to TSH receptors acting like TSH
Cause:
-LOW TSH
-HIGH T3 AND T4
What happens in Hashimotos disease?
Auto antibodies destroy thyroid tissue
Causes:
-HIGH TSH
-LOW T3 and T4
HYPOTHYROIDISIM
What hormone do parafollicular cells produce and where are they found?
Calcitonin (Peptide hormone)
Thyroid gland
What type of cells are parafollicular cells?
Neuroendocrine cells
What is the effect of parafollicular cells producing calcitonin?
DECREASES PLASMA Ca2+ LEVELS
COUTERACTS PTH
How does Calcitonin decrease plasma Ca2+ levels?
Inhibits osteoclast activity so inhibits bone resorption
Inhibits renal calcium and phosphate re absorption
What is the role of the parathyroid gland?
Monitors plasma calcium concentrations
What hormone does the parathyroid gland produce which increases plasma Ca+ concentration?
PTH
How does PTH increase Ca2+ levels in the plasma?
Stimulates osteoclast activity (stimulates bone resorption)
Prevents calcium loss by kidneys and more calcium absorbed by GI tract
What is indicative of Hypoparathyroidism?
Hypocalcaemia
Hyperphosphatemia
What occurs as a result of parathyroid dysfunction?
Affects ability to regulate Calcium levels
Affects nerve conduction, muscle contraction, bone strength
What is the shape of the right adrenal gland?
Pyramid
What is the shape of the left adrenal gland?
Crescent shape
Which part of the adrenal gland is endocrine tissue?
Adrenal cortex
Which part of the adrenal gland is neuroendocrine tissue?
Adrenal Medulla
What is the name of the parenchyma (functional cells) that produce the Catecholamines in the adrenal glands?
Chromaffin cells
How are chromaffin cells special?
They are modified post-synaptic sympathetic neurones
Pre-synaptic sympathetic nerve fibres pass directly to them
What hormones (Catecholamines) do the Chromaffin cells produce?
Adrenaline
Noradrenaline
What 3 layer compromise the Adrenal Cortex?
Zona Glomerulosa (outer)
Zona Fasiculata (middle)
Zona Reticularis (inner)
Remember GFR
What steroid hormones (Corticosteroids) does the Zona Glomerulosa produce and what is their function?
Mineralocorticoids (e.g Aldosterone)
Regulates Blood Pressure BP
What steroid hormones (Corticosteroids) does the Zona Fasiculata produce and what is their function?
Glucocorticoids (e.g Cortisol or Cortisone)
Increases blood glucose levels (Glycogenolysis, lipolysis, proteolysis)
What steroid hormones (Corticosteroids) does the Zona Reticularis produce and what are their function?
Androgen precursors (DHEA)
Go onto to make sex hormones
What is the definition of Stress?
A state of real or perceived threat to homeostasis
What is the stress response?
It is the complex range of responses involving the endocrine, nervous and immune systems collectively to maintain homeostasis in the presence of aversive stimuli/stressors
What behavioural changes does the activation of the stress response cause?
Increased awareness
Increased cognition
Euphoria
Enhanced analgesia (not feeling pain)
What physiological adaptation are caused by the activation of the stress response?
Increased Cardiovascular tone
Increased respiratory rate
Increased intermediate metabolism
In terms of sympathetic and parasympathetic pathways, what is the affect of cortisol?
Shuts down parasympathetic pathways
What are the 3 overall affects of the corticosteroids produced by the adrenal cortex in the fight or flight response?
Inc BP
Inc Blood glucose
Inhibit parasympathetic pathways
Where is Corticotropin Releasing Hormone made?
What is its affect?
CRH made in hypothalamus
Travels to anterior pituitary via Hypothalmo-hypophyseal portal system
Simulates ACTH production (Adrenocorticotropic Hormone)
ACTH binds to adrenal cortex simulating production of Adrenal corticosteroids
Why is the secretion of adrenaline and noradrenalin considered neurocrine secretion?
Chromaffin cells = post syntactic neurones
Release hormones directly into blood from neurone
What is the long term stress response relative to the adrenal glands?
High Mineralocorticoids = High sodium low potassium, increased blood volume and pressure
High Glucocorticoids = Increased proteolysis, lipolysis increased blood glucose then causes supressed immune system
How are cells grouped in the pancreas?
In lobules
Which part of the pancreas carries out the exocrine function?
Acinar glands/cells
What are zymogen granules?
Specialised storage organelles which package, process and store they digestive enzymes in the exocrine pancreas
What ducts are present in the pancreas?
Intercalated ducts join lobules which then join to the pancreatic duct which joins to the bile duct
Where do the digestive enzymes of the pancreas get released into?
The duodenum
What are the smaller paler sections called found in the pancreatic lobules?
Islets of Langerhans
What are the main important cells in the islets of Langerhans and what do they produce?
A = glucagon
B = Insulin
Delta = Somatostatin
Function of glucagon:
Increase blood glucose
Function of insulin:
Decrease blood glucose
Function of somatostatin:
Inhibits insulin and glucagon secretion
What is the name if the cell that produces the digestive enzymes in the pancreas?
Acini
