S11) The Endocrine System Flashcards
Distinguish between the parasympathetic and sympathetic actions in terms of the following:
- Eye
- Salivary glands
- Heart
- Lung
- Intestines
- Kidneys / Gallbladder
- Bladder
- Rectum
What is endocrine communication?
Endocrine communication involves endocrine cells producing hormones which travel through the blood to reach all parts of the body
What is neuroendocrine communication?
Neuroendocrine communication involves neurosecretory cells releasing neurohormones which travel via the circulation to distant target cells e.g. hypothalamus, posterior pituitary and adrenal medulla
What are the organs of interest in the endocrine system?
- Liver
- Stomach
- Duodenum
- Pancreas
- Kidney
- Adrenal glands
Identify the hormones secreted from the following organs:
- Liver
- Kidney
- Duodenum
- Liver: angiotensin, IGF, thrombopoietin
- Kidney: renin, erythropoietin, thrombopoietin
- Duodenum: secretin, CCK
Identify the hormones secreted from the following organs:
- Pancreas
- Stomach
- Pancreas: insulin, glucagon, somatostatin
- Stomach: gastrin, ghrelin, somatostatin, histamine
Identify the hormones secreted from different parts of the adrenal glands
- Adrenal medulla: adrenaline, noradrenaline, dopamine
- Adrenal cortex: glucocorticoids, mineralocorticoids
What are the main functions of hormones?
- Reproduction
- Metabolism and energy balance
- Growth and development
- Body defences
- General homeostasis (water, nutrient, electrolyte balance)
Distinguish between hormone action on cell surface receptors and intracellular receptors
Describe the synthesis, storage, transport, receptor, response of peptide hormones
- Synthesis: made in advance
- Storage: stored in secretory vesicles
- Transport: dissolved in plasma
- Receptor: cell surface receptor
- Response to receptor-ligand binding: activation of secondary messenger systems
Provide some examples of peptide hormones
- Insulin
- Glucagon
- PTH
- ACTH
Describe the synthesis, storage, transport, receptor, response of catecholamines (amino-acid derived hormones)
- Synthesis: made in advance
- Storage: stored in secretory vesicles
- Transport: dissolved in plasma
- Receptor: cell surface receptor
- Response to receptor-ligand binding: activation of secondary messenger systems
Provide some examples of catecholamines (amino-acid derived hormones)
- Adrenaline
- Noradrenaline
Describe the synthesis, transport, receptor, response of steroid hormones
- Synthesis: made on demand
- Transport: bound to carrier proteins
- Receptor: intracellular receptor (cytoplasm / nucleus)
- Response to receptor-ligand binding: activation of genes for transcription & translation
Provide some examples of the steroid hormones
- Oestrogen
- Aldosterone
- Cortisol
Describe the synthesis, storage, transport, receptor, response and examples of thyroid hormones
- Synthesis: made in advance
- Storage: precursor stored in secretory vesicles
- Transport: bound to carrier proteins
- Receptor: intracellular receptor (nucleus)
- Response to receptor-ligand binding: activation of genes for transcription & translation
Provide some examples of thyroid hormones (amino-acid derived hormones)
- Thyroxine
- T4
Identify some processes that the hypothalamus facilitates
- Thermoregulation (sweating, shivering)
- HR & BP
- Feeding & satiety
- Circadian rhythms
- Lactation
Describe the surface anatomy of the pituitary gland
The pituitary is divided into two lobes:
- Anterior pituitary
- Posterior pituitary
Discuss the hypothalamo-hypophyseal portal system and the hormones involved
- Anterior pituitary – 4 stimulatory and 2 inhibitory hormones travel via the hypothalamo-hypophyseal portal system
- Posterior pituitary – ADH and oxytocin travel from the hypothalamus
What is stress?
Stress is commonly defined as a state of real or perceived threat to homeostasis
What is the stress response?
The stress response is the complex range of responses involving the endocrine, nervous and immune systems to maintain homeostasis in the presence of aversive stimuli (stressors)
What are the main effectors of the stress response?
- Hypothalamus
- Anterior pituitary gland
- Adrenal gland
What are the physiological adaptations of the stress response?
- Increased blood pressure
- Increased respiratory rate
- Increased blood glucose
- Inhibition of general vegetative functions (feeding, digestion, growth, reproduction, immunity)
What are the behavioural adaptations of the stress response?
- Increased awareness
- Improved cognition
- Euphoria
- Enhanced analgesia
The short-term stress response is stimulated by the release of catecholamines from the adrenal medulla.
Describe the effects of this
- Increased BP, HR, RR
- Increased blood glucose (glycogen broken down)
- Increased metabolic rate
- Increased alertness
- Decreased vegative functions
The long term stress response is stimulated by mineralocorticoid / glucocorticoid release.
Describe the effects of mineralocorticoid release
- Retention Na+ and H2O by the kidneys
- Increased blood volume and blood presure
The long term stress response is stimulated by mineralocorticoid / glucocorticoid release.
Describe the effects of glucocorticoid release
- Conversion of proteins and fats to glucose / broken down for energy
- Increased blood sugar
- Immune system suppression
What are the adrenal cortical hormones?
- Glucocorticoids (cortisol)
- Mineralocorticoids (aldosterone)
Adrenal cortical hormone secretion is controlled through the HPA axis.
Outline this
What are chromaffin cells and where are they found?
Chromaffin cells are epithelioid cells & modified neurons which are found in the central portion of the adrenal gland (the medulla)
What do chromaffin cells do?
- Chromaffin cells respond to nerve impulses carried by presynaptic sympathetic nerve fibres by releasing their secretory products of noradrenaline and adrenaline
- Therefore, chromaffin cells are considered the equivalent of postsynaptic neurons
Thyroid hormone secretion is controlled via the HPT axis.
Outline this
Describe the structure and function of the pineal gland
- Structure: midline structure in the brain
- Function: produces melatonin
Melatonin is involved in control of circadian rhythm.
Describe its control & neuronal pathway
- The neuronal pathway is from retina → hypothalamus → pineal gland
- Light exposure inhibits melatonin release
