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Describe Endocrine Glands
- Derived from epithelial tissue
- Primary endocrine organs (ex. thryoid glands)
- Secondary endocrine organs (ex. heart)
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What are the primary endocrine organs?
- Hypothalamus & pituitary gland
- Pineal gland
- Thyroid gland & parathyroid gland
- Thymus
- Adrenal glands
- Pancreas
- Gonads
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Where are the hypothalamus and pituitary gland located?
Brain, connected by the infundibulum
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How many lobes are in the pituitary gland of a human? ... a pig?
2 - posterior, anterior
3 - posterior, anterior, intermediate
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What are the hormones of the posterior pituitary?
- Antidiuretic Hormone (ADH)
- - Paraventricular nucleus
- - Water balance and osmolarity
- Oxytocin
- - Supraoptic nucleus
- - Millk ejection
- - Uterine contractions during pregnancy
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What is the role of the Hypothalamic-Pituitary portal system?
Links two capillary beds`
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What do Tropic Hormones do?
Affect release of another hormone
- Releasing hormones
- Inhibiting hormones
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What is the common tropic hormone pathway?
1. Hypothalamus - secretes tropic hormone into capillary bed, blood enters veins
2. Anterior Pituitary - blood enters ant. pit. secretory cells through cap. beds, alters release of ant. pit. tropic hormone, ant. pit. tropic hormones enter bloodstream in cap. bed
3. Endocrine Gland - blood travels to distant endocrine gland to trigger release of hormone
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What two tropic hormones are inhibitory?
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What controls hypothalamic tropic hormone release?
- Neural input
- Hormonal - negative feedback
- Circadian rhythm
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What is circadian rhythm?
- 24 hour oscillation (sleep at night, awake during day)
- Controlled by Suprachiasmatic Nucleus of Hypothalamus
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Give an example of a short loop negative feedback in the endocrine system
Hypothalamus - Anterior Pituitary negative feedback loop
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Give an example of a long loop negative feedback in the endocrine system
Hypothalamus - Adrenal Gland negative feedback loop
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Decribe the Pineal Gland
Glandular tissue in brain
- Secretes melatonin
- - Function unknown
- - May be involved in circadian rhythm
- - Induces sleep
- - Suppresses reproductive functions
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What are the hormones of the thyroid gland?
- Thyroid hormones which regulate metabolism
- T4 - tetraiodothyronin
- T3 - triiodothyronine
Calcitonin which regulates calcium levels in blood (decreases)
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What does the Parathyroid Hormone (PTH) do?
Regulates calcium levels in blood
- Enhances
- - release of Ca from bones
- - Ca re-absorption from kidneys
- - re-absorption of Ca in intestines
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What does the Thymus secrete and what purpose do these secretions serve?
- Thymosin (alpha, beta, gamma)
- Regulates T cell funtion
- Involved in tissue repair
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Where are the adrenal glands located?
Above the kidneys
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What are the hormones of the Adrenal gland?
- Adrenocorticoids
- - Mineralocorticoids (aldosterone)
- - Glucocorticoids (cortisol)
- - Sex hormones (androgens)
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Describe Mineralocorticoids
- Secreted from zonae glomerulosa
- Regulates Na and K levels
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Describe Glucocorticoids
- Secreted from zonae fasciculata and reticularis
- Regulates body's response to stress
- Regulates metabolism
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Describe sex hormones (androgens)
- Secreted from zonae fasciculata and reticularis
- Regulate reproductive function
- Not main sex hormone producer, gonads are
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What does the Adrenal Medulla secrete?
- Secretory cells = Chromaffin cells
- - 80% Epinephrine
- - 20% Norepinephrine
- - <1% Dopamine
Under neural control, release must be very quick - Fight or Flight
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What does the exocrine pancreas secrete?
Acinar and duct cells secrete fluid and enzymes which enter digestive tract via pancreatic duct
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What cells are in the endocrine pancreas?
- Islets of Langerhans
- - Alpha cells (glucagon)
- - Beta cells (insulin)
- - Delta cells (somatostatin)
- - F cells (pancreatic polypeptide)
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What are the gonad and what hormones do they secrete?
- Male - testes
- - Testosterone
- - Androstenedione
- Female - ovaries
- - Estadiol
- - Progesterone
- - Placenta of pregnant female
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What are the secondary endocrine organs?
- Heart
- Kidneys
- GI Tract
- Liver
- Skin
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What controls the hormone levels in blood?
- Rate of hormone secretion
- Amount of hormone bound to plasma proteins
- Rate of hormone metabolism
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What are the sites of hormone metabolism?
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What can lipophilic be stored in?
Adipose tissue
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