Endocrinology Flashcards
Define the term hormone and describe how hormones can be classified according to their chemical composition.
HORMONE - A regulatory substance produced in an organism and transported in tissue fluids such as blood to stimulate specific tissues/cells.
Classifications of hormones
STEROID - Cytoplasmic/nuclear receptors
PEPTIDE - Membrane receptors
AMINE - Similar to steroid hormones - activates transcription of specific genes
Distinguish between exocrine and endocrine glands.
EXOCRINE
A gland which releases a secretion external to or at the surface of an organdie means of a canal or duct.
ENDOCRINE
Secrete their products, hormones, directly into the blood rather than through a duct
Identify the endocrine glands and describe the effects of the hormones they produce.
HYPOTHALAMUS - Produces releasing hormones. TRH, PRF, PRIF, CRH, GnRH, GHRH & SS
ANTERIOR PITUITARY GLAND - TSH (Thyroid stimulating hormone, increases basal metabolic rate), PRL (Prolactin, increases milk secretion), ACTH (adrenocorticotrophic hormone, increases cortisol production), LH (Luteinizing hormone, ovulation), FSH (Folicle stimulating hormone), hGH (Human growth hormone)
POSTERIOR PITUITARY GLAND - ADH (anti-diuretic hormone, works on kidneys), Oxytocin (Child birth and lactation)
THYROID GLAND - Thyroxine, tri-iodothyronine and calcitonin (lowers Ca and phosphate levels in the blood)
ADRENAL GLANDS - Adrenaline and Noradrenaline
KIDNEYS - EPO (increases RBC production), Calcitrol (promotes calcium absorption)
OVARIES - Oestrogen
TESTES - Progesterone
Describe how hormones are regulated.
Hormones are self-regulating via negative feedback systems.
Describe the structure of the hypothalamus and the pituitary gland and list the hormones each produces.
HYPOTHALAMUS - located in the diencephalon, produces releasing hormones (TRH, PRF, PRIF, CRH, GnRH)
PITUITARY GLAND - Split into posterior and anterior.
- Anterior (TSH, PRL, ACTH, LH, FSH, hGH)
- Posterior (ADH, Oxytocin)
Describe the role of the hypothalamus in controlling the anterior and posterior pituitary.
Produced the releasing hormones that travel to the pituitary gland. The pituitary gland then produces stimulating hormones. If less releasing hormone is produced, less stimulating hormone will be produced.
Give examples of hormone-producing tissues that are not classical endocrine glands.
Heart - ANP
Brain - BNP
Small intestine - CCK, Secretin
Pineal gland - Melatonin
Describe hormone-induced physiological changes that occur when a person is stressed.
STRESS -> corticotrophin releasing hormone -> adrenocorticotrophic hormone -> adrenal cortex -> cortisol secretion -> speed up heart, redirect blood from GI tract to muscles, vasodilation of blood vessels, dilation of pupils
Outline the structural and functional organisation of the Autonomic Nervous System (ANS)
Split into the parasympathetic (rest-and-digest) and sympathetic (fight-or-flight) systems. Sympathetic post-ganglionic neurones are long and produce noradrenaline as a neurotransmitter. All others are acetylcholine.
Illustrate the pre-ganglionic and post-ganglionic elements of autonomic innervation.
SYMPATHETIC
Pre = short, Post = long
PARASYMPATHETIC
Pre = long, Post = short
Name the main neurotransmitters of the ANS and identify their sites of release.
Acetylcholine
Released at all synapses apart from post-ganglionic in the sympathetic system
Noradrenaline
Released at post-ganglionic synapses of the sympathetic division
Name 3 differences between the parasympathetic and sympathetic divisions of the ANS
Neurotransmitters - Sympathetic uses noradrenaline as well as ACh
Structure - Sympathetic has short pre-ganglionic and long post-ganglionic, parasympathetic is the other way around
Positioning - Sympathetic come from the thoracic and lumbar sections of the spinal chord, parasympathetic comes from the brain and cerviacle region and the brain.
Describe the adrenal gland, its hormones and its interaction with the ANS
The adrenal gland has 3 zones, zona glomerulosa, zona fasiculata and zona reticularis.
The adrenal medulla is derived from neural tissue. Hormones are able to act on sympathetic effector cells.
