Endocrine system is ____
Ductless, products are released directly into the bloodstream
Hormone
Biologic products that act on target cells
- production vs activity relies on other systems
- must be delivered, receptor binding specific, ability to respond
Steroid
- cholesterol derived
- gonadal
- adrenocortical
Peptide, polypeptide, proteins
- amino acid based
- thyroid, pancreas, some pituitary
Activity of hormone is based on _____
Mechanism of getting to 2nd messenger
Amino acid derivatives
- serotonin
- bradykinin
Arachadonic acid derivatives
- prostaglandins
- leukotrienes
- prostacyclins
Target cells
- effector organs
- receptor-mediated activity
- cell surface “second messenger”: cAMP, diacyl glycerol, inositol triphosphate, cGMP
- intracellular receptors: steroids (carrier proteins)
Negative feedback
If you block signal of B going to C, then C will diminish and you will have a buildup of B
Endocrine organs
- pituitary/hypothalamus
- pineal (3rd eye)
- thyroids
- parathyroids
- adrenals
- pancreas
- gonads
Pituitary/hypothalamus
- master gland
- connected at base of brain
- sella tursica (Turkish saddle)
- Rathke’s pouch
- combo of both neural and epithelial tissue
- beneath the thalamus and above the pituitary is the hypothalamus
2 portions
- anterior pituitary: adenohypophysis = epithelial
- posterior pituitary (neurophypophysis) = neural
Anterior pituitary hormones
Pars distalis: have control over entire body - ACTH - TSH - FSH - LH - GH Pars intermedia - MSH Pars tuberalis: the stalk - ACTH, FSH, LH
Anterior pituitary cells
Pars distalis - acidophils (stain pink) - basophils - chromophobes (take up little stain) Pars intermedia - basophils - chromophobes Pars tuberalis
Posterior pituitary
- supraoptic and paraventricular nuclei
- pars nervosa
- infundibulum
- hormones: oxytocin, and ADH
Is the posterior pituitary endocrine?
Techinically, no because it is not glandular, but it still releases products directly into the bloodstream
Hypothalamus
- regulates pituitary function via releasing hormones
- remember: negative feedback
Negative feedback system of the hypothalamus
Hypothalamus releases hormone –> passes thru portal system –> impacts pars distalis, activating the adrenal gland –> TSH goes to thyroid –> thyroid hormone negatively impacts the hypothalamus
Pineal gland
Aka: pineal body, epiphysis cerebri, 3rd eye (light sensitive)
- melatonin
Endocrine pattern
Highly vacoulated cytoplasm
Thyroid
- bilateral anterior cervical region
- embryologic branchial arches
- growth and metabolism
- hormones: T4, T3, calcitonin
Thyroid follicles
- follicular cells
- parafollicular cells: secrete calcitonin
- colloid: thyroglobulin
Are there tight junctions between thyroid follicles?
Yes, do not want thyroglobulin leaking out without going thru a cell first
Parathyroid glands
Four - cranial and caudal pole of each thyroid - para = besides Branchial arch derived (3,4) Calcium/phosphorous metabolism - rickets - osteomalacia
