Endocrinology Flashcards
What are the functions of the parasympathetic system?
Rest/digest vs Fight/Flight Sympathetic
What is neurocrine communication and where does it occur?
Neutrons release transmitters into blood to target cells with receptors.
It occurs at anterior pituitary, posterior pituitary and adrenal medulla and hypothalamus.
What does the thymus gland produce?
Thymus produces thymosin which aids T-cell maturation
What are the properties of peptide hormones?
- Made in advance and stored in secretory vesicles
- Dissolved in plasma
- Cell membrane receptor
- Examples include insulin, glucagon, Prolactin, ACTH, PTH, gastrin
What are the properties of steroid hormones?
- Synthesised on demand from precursors
- Bound to carrier proteins
- Intracellular receptor
- Examples include testosterone, oestrogen, aldosterone, progesterone
What are the properties of thyroid hormones?
- Made in advance and stored in secretory vesicles
- Dissolved in plasma
- Cell membrane receptor
- Examples or thyroxine and triodothryonine
What are the properties of catecholamines?
- Made in advance and stored in secretory vesicles
- Bound to carrier proteins
- Intracellular receptor
- Examples are adrenaline, noradrenaline
How do cell surface receptors work differently to intracellular receptors?
Intracellular receptor induce changes to mRNA expression whereas cell surface receptors work via secondary messengers
What are the functions of the hypothalamus?
Hypothalamus deals with
– Thermoregulation, panting, sweating, shivering
– Plasma osmolalty via osmoreceptors
– Heart rate, blood pressure
– Feeding, satiety, GIT regulation
– Circadian rhythms, wakefulness, sleep (afferents from retina)
– Autonomic input/stimulation via connections to the sympathetic and
parasympathetic systems
– Emotion, sexual behaviour
– Lactation (suckling/baby crying)
What does the hypothalamus produce?
- ADH and oxytocin that travel to posterior pituitary
- 6 hormones that travel via the hypothalamo-hypophyseal portal system to the anterior pituitary, 4 stimulatory, 2 inhibitory
Give a definition of stress
Stress is commonly defined as a state of real or perceived threat to homeostasis. Maintenance of homeostasls In the presence of aversive stimuli (stressors) requires activation of a complex range of responses involving the endocrine, nervous, and immune systems, collectively known as the stress response. Activation of the stress response initiates a number of behavioral and physiological changes that improve an individual’s chance of survival when faced with homeostatic challenges
What are some behavioural changes and physical adaptations that accompany the stress response?
Behavioral effects of the stress response include increased awareness, improved cognition, euphoria, and enhanced analgesia.
Physiological adaptations initiated by activation of this system include increased cardiovascular tone, respiratory rate, and intermediate metabolism, along with inhibition of general vegetative functions such as feeding, digestion, growth, reproduction, and immunity
The principal effectors of the stress response are localized in the hypothalamus, the anterior lobe of the pituitary gland, and the adrenal gland
What are chromaffin cells?
The central portion of the adrenal gland, the medulla, is composed of a parenchyma of large, pale-staining epithelioid cells called chromaffin cells.
Numerous myelinated, presynaptic sympathetic nerve fibers pass directly to the chromaffin cells of the medulla.
When nerve impulses carried by the sympathetic fibers reach the catecholamine-secreting chromaffin cells, they release their secretory products adrenaline and noradrenaline (neurocrine). Therefore, chromaffin cells are consideredthe equivalent of postsynaptic neurons
What are the hormones of the posterior pituitary?
The posterior pituitary hormones are oxytocin and ADH, both are produced in the hypothalamus, travel down the neuronal axons and are secreted adjacent to the capillaries of the posterior pituitary.
What does the pineal gland produce?
It produces melatonin. Melatonin is involved in control of circadian rhythmn. Light exposure inhibits melatonin release. The neuronal pathway is from retina to
hypothalamus to pineal gland
Melatonin inhibits release of gonadotrophins (LH and FSH)
Perhaps most important thing to know is that it calcifies in early adulthood and is therefore visible on skull x-rays.
