The Endocrine System Flashcards
Where does the sympathetic NS prioritise blood to in an emergency?
prioritises blood flow to brain, skeletal muscle, heart in emergency – skin vasoconstriction to minimise blood lose in injury, venoconstriction = increase cardiac return
Define endocrine
secrets hormones into the blood without ducts, wide spread, long lasting effects
Define neurocrine
neuron secrets substance into blood = hypothalamus, posterior pituitary, adrenal medulla
What are hormones and their main function ?
50 types, Control/regulate –> reproduction, metabolism, energy balance, growth/development, body defences, homeostasis. Can only trigger a reaction in specific cells = target cells with the right receptors, AA: cell membrane, steroid: intracellular. Hormone cascade: some hormones exist to control other hormones
What are the 2 main types of hormones, and where are their receptors?
AA (water soluble) or steroidal (lipid soluble). Protein hormone –> surface receptors. Steroid hormone –> intracellular receptors
What is a gland?
any structure that makes and secrets a hormone
What is the thymus?
Atrophy in teens. Function –> maturation of bone marrow dervied stem cells into T cells = thymic education. Prod thymosin = promotes T cell maturation
What is the pituitary?
Pea-sized structure located at base of the brain, just below hypothalamus, 2 lobes = anterior blood attachment, posterior nerve attachment
Describe the posterior pituitary
Connected by neurones, prod: oxytocin, ADH – both prod in hypo, travel neuronal axons, secreted to capillaries
Describe the anterior pituitary
Connect via blood supply, Prod: FSH= regulate growth and trigger sexual maturity, ACTH (adrenocorticotropic), TSH, LH, GW, prolactin
What is the thyroid gland?
Hypothalamic-pituitary-thyroid axis = thyroid gland prod thyroxin T3 T4 = -ve feedback loop on hypothalamus and anterior pit = anterior pit prod TSH, thyroid stim hormone. Controls metabolic rate
What are adrenal glands?
On top of kidneys. Adrenal cortical hormones = glucocorticoids (cortisol) mineralocorticoids (aldosterone)
Outline the HPA axis
hypothalamic release of corticotropin-releasing hormone (CRH). CRH binds to CRH receptors on anterior pituitary gland, adrenocorticotropic hormone (ACTH) is released. ACTH binds receptors on adrenal cortex and stimulates adrenal release of cortisol. Short/long –ve feedback from cortisol to AP and hypo
What are chromaffin cells?
Central = medulla = contains chromaffin cells (modified neurons) – nerve impulse = release adrenaline and noradrenaline –> considered neurocrine because chromaffin cells are considered the equivalent of postsynaptic neurones
What does the pancreas secrete?
BETA cells: Insulin. ALPHA cells: glucagon = regulates blood sugar
