Lecture 7: Endocrine system and stress physiology Flashcards
(36 cards)
What are the major processes the endocrine system controls?
Behaviour
-Reproduction
-Growth and development
-Maintaining electrolyte, water and nutrients balance of the blood
-Regulating cellular metabolism and energy balance
-Defences against stressors (neuroendocrine integration)
What are the 4 main endocrine axes? why are they important?
-The most chronic and prolonged response to stress events are the result of endocrine axes
- Adreno-cortical axis
- Somatotropic axis
- Thyroid axis
- Posterior pituitary axis
What types of hormones exist?
-Amino acid-based molecules (includes proteins, peptides and amines)
-Steroids (made from cholesterol)
-Lipids (prostaglandins)
Hormone interaction is very specific
How do hormones take action?
-Reception of the signal: hormone binds to specific receptor protein
-Signal transduction
-Response: a change in cells behaviour
One hormone can bind to a variety of receptors in various target cells- different response to the same hormone (depends where the hormone binds ie the receptor)
Ex Adrenaline, in heart cells causes cellar contraction, in liver cases glycogen breakdown
TRUE OR FALSE: Hormones can stimulate other hormones
TRUE
-This is the most common stimulus ex hormones of the hypothalamus stimulate the pituitary and hormones from the pituitary stimulate the adrenal cortex
-As the final (target cell) hormones increase they “feed back” to inhibit release of initial emulating hormones
-This leads to rhythmic relate- levels rising and falling again and again
TRUE OR FALSE: changing blood levels of certain ions and nutrients may also stimulate certain hormones
TRUE
-Ex decreasing blood calcium levels prompt release of parathyroid hormone (PTH)
-The blood calcium levels soon rise- ending the stimulus for PTH release
TRUE OR FALSE: in isolated cases only nerve fibres stimulate hormone release.
TRUE
-EX sympathetic nervous stimulation of the adrenal medulla to release noradrenalin and adrenal during periods of stress
What is the control of release by the negative feedback loop?
-Some internal or external stimulus triggers hormone secretion
-Leads to increase levels of hormones in the body
-The rising levels inhibits further hormone release
(regulated by neg feedback pop by levels in blood stream)
What are endocrine glands?
-Are ductless
-Release hormones into the blood or lymph
-Ex hypothalamus, pituitary, thyroid, adrenal gland
What is the hypothalamus’ role in the endocrine system?
-Receives info from nerves
-Sends nervous + endocrine signals
-Uses pituitary gland to relay directions (hormones) to other glands
-Posterior pit- composed of nervous tissue
-Anterior pituitary- composed of endocrine cells
What is the posterior pituitary’s role in the endocrine system?
-Acts as a storage for hormones produced in the hypothalamus
-The releases them into the blood stream
-OXYTOCIN:during parturition (birth) and lactation
-ANTIDIRECTIC HORMONE (ADH): inhibits or prevents urine volume production=blood volume increases
What is the anterior pituitary’s role in the endocrine system?
-Endocrine gland
-Produces and releases 6 hormones in total
1. Growth hormone
2. Prolactin
3. ACTH (adrenocorticotropic hormone)
4. TSH (thyroid stimulating hormone)
5. FSH (follicle stimulating hormone)
6. LH (luteinizing hormone)
1 and 2 effect non-endocrine target
Where is the adrenal glands and what does it do?
-It is essentially 2 endocrine organs
-Cortex (glandular)
-Medulla (neural)
medulla is central and is surrounded by the cortex
ON TOP OF KIDNEYS
What are the different parts of the adrenal cortex?
-Consists of 3 layers of cells (from outermost towards the centre)
-Mineralcorticoid-secreting area
-Glucocorticoid-secreting area
-Sex hormone secreting area
What is the adrenal medulla and what does it produce?
-Develops from a knots of nervous tissue
- Is stimulated by the sympathetic NS
-2 hormones -catecholaimes
-Epinephrine (adrenaline)
-Norepinephraine (Noradrenaline)
-Responsible for the fight or flight response
What is the thyroid gland and what does it produce?
-makes 2 hormones
- Thyroid hormone (major metabolic hormone)
- Calcitonin (Ca2+ metabolism)
-Thyroid hormones
-T3-triiodothyronine
-T4-thyroxine
Control rate of glucose levels burn into energy
What is a psychosocial Stressor?
- Must work through cognitive appraisal mechanics-cant directly cause the stress response
- They are real or imagined environmental events
-Stressful situation from experience processed stressful environment can trigger stress response
-ex speech in class or back to school new classmates/exam.
-Health exam can be + or -
- Have to access situation bc don’t know from + or -
What is biogenic stressor?
1.Work directly on neurological triggering nuclei- no cognitive-affect processing
2.EX of caffeine, nicotine, pain, extreme cold or heat-Cold or raining, still cause stress but don’t think about it
What is Eustress?
- Play behaviour
-Glucocortiids in blood can increase even tho its from a positive experience
-In clinical setting if take sample don’t know if its from + or -so behaviour is important
What is stress?
-Complex term referring to psychological and physiological changes that occur in response to real or perceived threat to homeostasis called ALLOSTASIS
-When encountering an aversive stumbles that is interpreted as potentially harmful the body initiated a complex pattern of endocrine, neural, and immunological activity (stress response)
What is allostasis?
-Achieving stability through change (psychological or physiological)
-Affects many body fins including change in:
-Cardio fxn
-Respiration
-Glucose metabolism.
-Muscle tension
-Digestion
What are the 2 board “stress” categories?
Eustress: “good Stress” is a + form of stress that may be preceded as pleasurable
-Can have similar physiological effects as distress ie increase heart rate and elevated glucocorticoids which in themselves are not harmful
-It is positive response to demands
-Ex running during play bout
Distress:
-Develops over a relatively long period of time
-However, acute distress can also occur in response to short, intense stressor
-An animal may be in distress even it appears to recover rapidly after removal of the stressor or the conclusion of the procedure
(prolonged, unpredictable, uncontrollable)
Both:General public often uses “stress” and “distress” interchangeably
-Broader construct of stress has become synonymous with distress
What is the stress response?
-Evolved to handle physical threats such as temp changes to the appliance of predator, psychological threats elicit a similar response
-Coping mechanisms/adaptive changes
-Behavioural reactions
-Activation of the sympathetic nervous system and adrenal medulla
-Secretion of stress hormones (glucocorticoids) can measure hormones
-Mobilization of immune system will be activated
-May involve at least one of the before minted systems although none of them is by itself necessary or sufficient to denote stress
-Physiological responses are not necessarily the same for all stressors, but some common ones
What is the transition from stress to distress?
-Depends on stressor: duration and intensity
-ex short term restraint- no marked problems in adaptation
-long term restraint- distress smites expressed by vocalizations and gastric ulcers
