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Body Logistics > 6. Endocrine Tissues > Flashcards

6. Endocrine Tissues Flashcards

1
Q

Give some examples of organs that contain endocrine cells and tissues.

A

Thymus, heart, liver, stomach, kidney, ovaries, testes.

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2
Q

Where is the pituitary gland located and what does it secrete?

A

Base of the brain.
Anterior - thyroid stimulating, adrenocorticotropics, FSH, LH, GH, prolactin.
Posterior - antidiuretic hormone/vasopressin, oxytocin

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3
Q

Where is the thyroid gland and what does it secrete?

A

Anterior to the trachea, in two lobes joined by ismus

Thyroxine T4, triiodothyronine T3

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4
Q

Where is the parathyroid gland and what does it secrete?

A

Lies on the dorsal surface of thyroid gland
4 glands - 2 pairs
Secretes para-thyroid hormone

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5
Q

Where are the adrenal glands located and what do they secrete?

A

Top of each kidney, two sections; medulla inner and cortex outer surrounding medulla.
Cortex secretes corticosteroids, steroid hormones.
Medulla - chromaffin cells, release of adrenaline and noradrenaline.

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6
Q

Where is the pancreas and what does it secrete?

A

Left of and behind the stomach, is both an exocrine and endocrine gland.
Exocrine secretes digestive enzymes into duodenum.
Endocrine has islets of Langerhans:
- Alpha - glucagons
- Beta - insulin

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7
Q

What endocrine hormones affect the heart?

Produced from the heart as can be an endocrine organ

A

Atrial natriuretic factors act on kidneys.
Relaxes arterioles inhibits renin and aldosterone
Prevents sodium reabsorption by kidney, less salt

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8
Q

What endocrine hormones does the stomach produce?

A

Gastrin stimulates gastric acid secretion
Ghrelin and leptin appetite control
Somatostatin inhibits secretion of hormones
Secretin stimulates secretion of water and bicarbonate

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9
Q

What endocrine hormones does the liver produce?

A

Insulin-like growth factor mediates GH dependent growth
Angiotensinogen precursor for angiotensin
Angiotensin increases blood pressure, vasoconstrictor
Thrombopoietin regulates production of platelets

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10
Q

What endocrine hormones does the duodenum produce?

A

Secretin stimulates of water and bicarbonate

Cholecystokinin stimulates pancreatic enzymes

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11
Q

What endococrine hormones does the kidney produce?

A

Renin converts angiotensin 1 to 2
Erythropoietin produces RBCs by bone marrow
Calcitriol promotes calcium absorption
Thrombopoietin regulates production of platelets

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12
Q

What are peptide hormones?

Describe their characteristics.

A

Glycoproteins, e.g. insulin, glucagon, prolactin, PTH
Made in advance and stored in secretory vesicles.
Dissolved in the plasma, receptors on membranes.
Activates second messenger systems.

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13
Q

What are steroid hormones?

Describe their characteristics.

A 
Synthesised on demand from precursors.
Bound to carrier proteins as lipophilic.
Receptors within nucleus or cytoplasm.
Activation of genes for transcription.
e.g. oestrogen, androgens, aldosterine, cortisol
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14
Q

What are catecholamines?

Describe their characteristics.

A

Made in advance stored in secretory vesicles.
Dissolved in plasma, attach to receptors on membrane.
Activate second messenger systems.
e.g. adrenaline, noradrenaline, also dopamine

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15
Q

What are thyroid hormones?

Describe their characteristics.

A

Made in advance as precursors, stored in vesicles.
Bound to carrier proteins, receptors on nucleus.
Activates genes for transcription and translation.
Thyroxine T4 and triiodothyronine T3.

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16
Q

What are lipid hormones?

A

Endocannabinoids are lipid neurotransmitters, can bind to cannbinoid receptors.
Anandimide acts on cannabinoid receptors throughout the body controlling pain.

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17
Q

What can the hypothalamus control?

A

Thermoregulation
Plasma osmolality
Heart rate and blood pressure
Feeding, circadian rhythms, emotion, sexual behaviour
Lactation, stimuli from autonomic nervous system

18
Q

What does the hypothalamus produce?

A

Vasopressin (ADH) and oxytocin

Six hormones that travel via the hypothalamo-hypophyseal portal system to anterior pituitary.

19
Q

Describe the structure of the pituitary gland

Also known as the hypophysis

A

Divided into two lobes, anterior and posterior joined by stalk known as infundibulum.

20
Q

What is a portal system?

A

Differ from typical circulatory route, blood passes through two sets of smaller vessels before returning to the heart.
Blood collects in portal vessels/veins then brancing into capillary network to second location before branching to heart.

21
Q

What are two examples of a portal system?

A

Hypothalamo-hypophyseal portal system

Hepatic portal vein

22
Q

Outline the development of the endocrine system?

A

From 5 weeks onwards.
1. Pituitary develops from neurohypophyseal bud and hypophyseal pouch (Rathke’s pouch)
2. Thyroid develops from 2nd pouch in pharynx
3. Parathyroid and thymus develop from 3rd/4th
4. Pancrease from foregut
5. Adrenals develops from intermediate mesoderm and neural crest, in centre of foetus
Takes 8-12 weeks to develop pituitary
Bud grows around mouth and Rathke’s pouch
Infundibulum grows around pouch pressing it, closes around mouth - pars intermedia cavity.

23
Q

Describe the main pathways within the posterior pituitary.

A

ADH affects kidneys.
Oxytocin - males, smooth muscle in prostate
In females, uterine smooth muscle, mammary glands.

24
Q

Describe the pathways for LH and FSH.

A

LH and FSH produced by anterior pituitary.
LH - ovaries to produce oestrogen, progestrone
- Testes to produces inhibin and testosterone.
Same for FSH.

25
Q

Describe some of the other pathways for the anterior pituitary lobe.

A

ACTH direct control by nervous system overrides, autonomic nervous system.
TSH to thyroid gland for T3 T4 release.
GH to liver to somatmedins to bone, muscle, tissue.
MSH melanocytes, make melanin.

26
Q

How are pituitary hormones controlled?

A

All subject to constitutive and regulated merocrine secretion, hence why there is always a small concentration of these hormones in the blood.

27
Q

Describe the levels of thyroid hormones in hypothyroidism and hyperthyroidism.

A

Hyperthyroidism - low TSH, high T3 and T4
Overactive production of T3/T4 but feedback to TSH.
Hypothyroidism - high TSH, low T3/T4
If there are low levels of T3/T4 will feed back to hypothalamus and pituitary for higher levels TSH.

28
Q

What is Hashimoto’s?

A

High TSH, low T3 and T4
Thyroiditis, hypothyroidism.
Autoimmune disease that gradually destroys thyroid gland, fatigue, weight gain, muscle pain.

29
Q

What is Grave’s disease?

A

TSI antibodies cause increases in T3 and T4 as act like TSH. Hence low levels of TSH.

30
Q

What are parafollicular cells?

A

Neuroendocrine cells that migrate into the thyroid during thyroid development in the embryo.
Produce calcitonin, independent of thryoid hormone synthesis. Inhibits osteoclast activity and renal calcium and phosphate reabsorption.

31
Q

What is the parathyroid gland?

A

Makes PTH to increase plasma calcium levels, causes bone to release more calcium.
Calcium is essential in nerve conduction and muscle contraction.

32
Q

Describe the characteritics of the adrenal medulla.

A

Composed of chromaffin cells, modified neurons.

Myelinated presynaptic sympathetic nerve fibres pass through these cells. Cause release of products.

33
Q

Describe the structure of the adrenal cortex.

A 
Three layers:
- Outer zone glomerulosa, aldosterone
- Middle zone fasciculata, corticoids
- Inner zone reticularis, androgen precursors, sex
Main for stress response
34
Q

What is the stress response?

A

A state of real of perceived threat to homeostasis.
Maintenance of homeostasis in the presence of stressors allows for activation of responses in endocrine, nervous and immune systems.

35
Q

Describe some of the changes during the stress repsonse.

A

Behavioural changes - increased awareness, improved cognition, euphoria, enhanced analgesia
Physiological adaptations - increased heart rate and respiratory rate, increased immediated metabolism.
Decrease in vegetative functions as not needed.

36
Q

Describe the pathway for the stress response.

A

Principle effectors are localised in the hypothalamus, anterior lobe of pituitary and adrenal gland.

  • Production of corticotrophic releasing hormone in hypothalamus.
  • Passes through HPP system into pituitary.
  • Corticotrophs in anterior pituitary allow production of adrenocorticotrophic hormone into blood.
  • ACTH receptors in adrenal cortex for response.
37
Q

How are chromaffin cells neurocrine secretion?

A

Sympathetic preganglionic signals pass down the spinal chord to the adrenal medulla, where chromaffin cells are the equivalent of post synaptic and release adrenaline.

38
Q

Describe the adrenal gland responses to stress.

A

Short term:
- Nerve impulses to preganglionic fibres and adrenal medulla to cause release of catecholamines.
Leads to increased heart rate, blood pressure, dilation of bronchioles, increased metabolic rate.
Long term:
- CRH to ACTH in pituitary, to adrenal cortex, corticoids.
Leads to retention of sodium and water, increased blood pressure, increased blood sugar levels.

39
Q

Describe the structure of the pancreas.

A

Grouped into lobules which contain lobes, connected by connective tissue. Connect through numerous intercalated ducts to make pancreatic duct.
Pancreatic duct joins with bile ducts to make common bile duct, which dumps all secretions into small intestine.
Intercalated duct lined with cuboidal epithelium.

40
Q

Describe the endocrine gland component of the pancreas.

A

These are the islets of Langerhans.
Alpha cells secrete glucagon.
Beta cells secretes insulin.
Delta cells produce somatostatin which inhibits these secretions.
G cells gastrin, EC cells secretin (enterochromaffin)

41
Q

Describe the exocrine function of the pancreas.

A

These are the acini.
Produce trypsinogen, chymotrypsinogen.
Lipase, amylase, ribonuclease (and deoxy) elastase.

Body Logistics (9 decks)

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