11.2 The Endocrine System Flashcards
What happens within the parasympathetic and sympathetic responses for the following organs and tissues:
Eyes, salivary glands, heart, lungs, stomach, liver, kidney (just for symp), intestine, bladder
- Contract pupil vs dilate pupil
- Stimulates saliva vs inhibits saliva
- Slows heartbeat vs accelerates heartbeat
- Constricts bronchi vs dilates bronchi
- Stimulates digestion vs inhibits digestion
- Stimulates bile release vs stimulates glucose release
- sympathetic - stimulates adrenaline and noradrenaline release
- Stimulates peristalsis and secretion vs inhibits
- Contracts bladder vs relaxes bladder
Which vessels do sympathetic nerve fibres innervate?
All vessels apart from capillaries and precapillary sphincter which follow local control
If a vessel had strong sympathetic tone, would this lead to vasoconstriction or vasodilation?
Strong sympathetic tone
Smooth muscle contraction
Vasoconstriction
If a vessel had weak sympathetic tone, would this lead to vasoconstriction or vasodilation?
Weak sympathetic tone
Smooth muscle relaxation
Vasodilation
What areas does the sympathetic division prioritise blood flow to in times of emergency?
Blood vessels leading to the brain, skeletal muscles and heart
Name 3 differences between the nervous and endocrine system.
- NS - neurones for messages, ES - blood used
- NS - fast moving but short-lived, ES- slower moving and lingering effects
- NS- localised, ES - targets broad areas
What are hormones and their functions?
Regulatory substance that travels in blood.
Control and regulate:
- reproduction
- metabolism and energy balance
- growth and development
- body defences
- general homeostasis i.e water nutrient, electrolyte balance
Name the main two types of hormones and their derivatives (2 each).
Glycoprotein derived -
Peptide and steroid
AA derived - tyrosine derived -
Catecholamines and thyroid
Name the four types of hormones derived from glycoproteins and tyrosine, their method of travel, receptor location and effect.
Peptide, steroid, catecholamine, thyroid
Peptide and catecholamine travel via plasma, receptors lie on cell surface, trigger a second messenger system.
Steroid and thyroid travel bound to carrier protein and receptors lie intracellularly, activate transcription and translation
What is a gland?
A structure that makes and secretes a hormone
Where is the thymus located and what does it do? (3)
1) Superior mediastinum
2) Fully formed and functional at birth but involutes after puberty
3) Thymic cell education - maturation of bone marrow derived stem cells into T cells using hormone thymosin
Difference between the connection from hypothalamus to anterior and then posterior pituitary?
Hypothalamus and anterior pituitary connected via blood - hypothalamo-hypophyseal portal system
Hypothalamus and posterior pituitary connected via neurone axons.
What is the hypothalamus and its function?
- Below thalamus in forebrain
- Point that Nervous system and endocrine system interact
- Thermoregulation, heart rate BP, circadian rhythms, feeding satiety and GI regulation, emotional and sexual behaviour, lactation, produces ADH and oxytocin that travel to posterior pituitary, produces thyrotrophin releasing hormone TRH that travels to anterior pituitary and then thyroid gland
What is the pituitary gland?
Pea sized body attached beneath hypothalamus. It has two lobes; anterior and posterior
It releases hormones responding to the releases of hypothalamus.
Explain the actions of the posterior pituitary
- Oxytocin and ADH produced in hypothalamus
- Travel down NEURONAL axons to posterior pituitary gland.
- Secreted into adjacent capillaries
Note Antidiuretic hormone acts on kidney for water retention
Note oxytocin targets breast for lactation and contraction of uterus for child birth - feel good hormone!
Explain the actions of the anterior pituitary
- Anterior pituitary makes its own hormones but need confirmation to release from hypothalamus
- Hypothalamus secretes hormones that travel through the hypothalamo-hypophyseal portal system (so blood) to anterior pituitary to stimulate or inhibit hormone release in anterior pituitary
- Releases prolactin - target breast for milk production, growth hormone - bone, gonadotropic hormones (FSH, LH) for gonads, thyroid stimulating hormone (TSH) for thyroid, ACTH (adrenocorticotrophic hormone) for adrenal glands.
What is the thyroid gland?
- Located in the base of neck
2. Regulation of metabolic rate
Explain the hypothalamo-pituitary-thyroid axis
- NEURONES in hypothalamus produce TRH (thyrotrophin releasing hormone)
- NEUROCRINE secretion into portal system
- Reach anterior pituitary and stimultates production of TSH (thyroid stimulating hormone) and ENDOCRINE secretion out of gland
- Reach thyroid producing thyroxine - T3 AND T4 - in blood
- Negative feedback as when T3 AND T4 reach hypothalamus, it stops producing TRH
What is the stress response?
- Real/perceived threat to homeostasis causes stress
- The presence of stressors activates endocrine, nervous and immune response
- Principle effectors are localised in hypothalamus, pituitary gland (Anterior), adrenal gland and changes :
- increased awareness, cognition, euphoria
- enhanced analgesia
- increased cardiovascular tone, respiratory rate, intermediate metabolism
- inhibition of vegetative functions (feeding, digestion, growth)
What are the adrenal glands?
On top of the kidneys.
Two parts:
Adrenal Glands
- produce adrenal corticoid hormones (glucocorticoids, mineralcorticoids)
- long term stress response
Adrenal medulla
- inner part of adrenal glands have chromaffin cells
- release adrenaline and noradrenaline into blood
- though of as postsynaptic neurones
- therefore neurocrine secretion
- short term stress response
What are chromaffin cells?
Inner part of adrenal glands - adrenal medulla.
Produce adrenaline and noradrenaline as a response to nerve impulse from hypothalamus to spina cord to adrenal medulla.
Considered neurocrine as cells are considered as post-synaptic neurones
Outline the HPA axis.
Hypophyseal-pituitary-adrenal axis
- Hypothalamus produces corticotropin releasing hormone
- pituitary gland produces ACTH
- stimulates adrenal release of cortisol - gluco and mineral
- long term stress response
What does the pancreas secrete?
Alpha cells secrete glucagon to increase blood sugar
Beta cells secrete insulin to lower blood sugar
What is the pineal gland and how does it work?
- Located between two hemispheres in groove
- Produces melatonin to regulate circadian rhythms
- retina recognises light, information to hypothalamus, information to pineal gland
- inhibition of melatonin produced
- less sleep - Inhibits LH, FSH
- Calcified in early adulthood
