The Endocrine System Flashcards
1.1 Define a hormone.
Specialised chemical messengers that alter the activity of a target cell.
1.1 Define the endocrine system.
A controlling system that produces and secretes hormones to influence metabolic activities through the blood.
1.2 Difference between endocrine and exocrine glands.
Exocrine glands secrete through ducts onto an epithelial surface. Endocrine glands secrete messengers into the bloodstream.
1.3 List 3 similarities and differences between the endocrine and nervous systems
Similarities: (x3)
○ Act via receptors
○ Hormones and neurotransmitters have multiple effects on the same organ
Chemicals can act as both neurotransmitters and hormones
Differences: (x3)
○ Communication: Endocrine communicates via chemicals, nervous system communicates via chemicals and electrical signals.
○ Distribution: Endocrine is widespread, nervous system is localised and specific.
○ Reaction to stimuli: endocrine is slow, nervous is fast
1.4 List the 2 main chemical classes of hormones and give examples of each
Steroids: Testosterone
Non-stoirds: Adrenaline/melatonin
1.5 Describe how hormones are transported to their site of action
Steroid are hydrophobic, must bind to transport hormones in blood. Target cells in nucelus
Non steroids are hydrophillic and mix easily with blood plasma. Target cell is cell membrane
1.6 Describe how hormones stimulate their target cells & state any differences between the main chemical groups of hormones
Steroid: lipid soluble & receptors are found within target cells cytosol. Binds to receptor molecule
Non steroids: cannot pass through cell membrane. Bind to receptor proteins on cell surface which activates second messengers (cAMP)
1.7 Describe how target cells can adjust their sensitivity to a hormone
Sensitivity = number of receptors
Up-regulation = increased cell receptors and cell sensitivity
Down regulation = decreased cell receptors and cell sensitivity
2.1 Describe the anatomy of the hypothalamus & pituitary gland & their relationship to each other (Hypothalamus)
Location: region of the diencephalon, forms the floor/part of walls of third ventricle. Superior to pituitary gland.
Function: major control centre of endocrines and ANS.
2.1 Describe the anatomy of the hypothalamus & pituitary gland & their relationship to each other (Pituitary)
Location: base of brain, inferior to hypothalamus, in sella turcica
Two regions: anterior and posterior
Connected to hypothalamus through stalk with a blood portal system. neural linkage for posterior pituitary and hypothalamus
2.2 List hormones produced by the hypothalamus, Whats the target organ/s or tissue & state principal effects of (TRH)
TRH: Thyrotropin-releasing hormone
Promotes secretion Prolactin (PRL) and Thyroid-stimulating hormone (TSH)
2.2 List hormones produced by the hypothalamus, Whats the target organ/s or tissue & state principal effects of (CRH)
(CRH) - Corticotropin-releasing hormone
Promotes secretion Adrenocorticotropic hormone (ACTH)
2.2 List hormones produced by the hypothalamus, Whats the target organ/s or tissue & state principal effects of (GnRH)
(GnRH) - Gonadotropin-releasing hormone
Promotes secretion follicle-stimulating hormone (FSH) and Luteinizing hormone (LH)
2.2 List hormones produced by the hypothalamus, Whats the target organ/s or tissue & state principal effects of (GHRH)
(GHRH) - Growth hormone-releasing hormone
Promotes secretion Growth hormone (GH)
2.2 List hormones produced by the hypothalamus, Whats the target organ/s or tissue & state principal effects of (PIH)
(PIH) - Prolactin-inhibiting hormone
Inhibits secretion Prolactin (PRL)