Endocrine system, physiology of domestic animals, test 3
Nerve response signals hormone.
Suckling stimuli travels up spinal cord to hypothalamus
neurocrines secrete oxytocin
travels down axon, released in blood
contraction of smooth muscle of mammary gland
milk to teat
Endocrine vs Neuro
NS fast, short duration
ES cellular metabolism, growth and reproduction. Long term, slow-acting.
Interact closely--dopamine, histamine, somatostatin are in endocrine and neuro. Endocrine cells can be controlled by neurons.
a cell or group of cells that secretes a chemical messenger (hormone) directly into the bloodstream.
a chemical messenger that is produced by one or a group of cells, secreted directly into the bloodstream and transported to distant target cells, eliciting a response
neurohormones. Chemical messengers secreted by axonal terminal of neuron directly into bloodstream.
can act on distant cell. Oxytocin.
a chemical messenger secreted by a cell into ISF that acts on a DIFFERENT type of neighboring cell.
a chemical messenger secreted by a cell into ISF that acts on the cell of origin or an identical neighbor.
Endocrine hormone classification
Peptide hormone: peptides, polypeptides, proteins, produced by adrenal medulla, pituitary gland, hypothalamus, thyroid gland, parathyroid gland, pancreas, placenta, endometrium
Steroid hormone: derived from cholesterol. Produced by gonads, adrenal cortex, fetal membranes (placenta).
Protein hormone synthesis
synthesized as preprohormones, cleaved in rough ER to make prohormones, golgi apparatus to form active hormones, STORED in granules, released in response to stimuli
steriod hormone synthesis
made from cholesterol in the liver
released AS SYNTHESIZED
Transport of hormones in blood
Peptide/protein hormones are hydrophilic, dissolve in plasma
steroid and thyroid hormones are lipophilic carried in plasma bound to proteins. Must unbind before it can penetrate a target cell.
Peptide hormone-cell interaction
receptors are on or next to membrane (outside).
changes enzymatic activity in target cell if stimulated
effect occurs fast, lasts less than 1 hour
steroid hormone-cell interaction
stimulated receptor changes synthesis of specific proteins
effect occurs slow, lasts hours to days
Functions of the endocrine system
control of physiologic functions like
metabolism (energy and mineral)
Hormones in energy metabolism
hormones in mineral metabolism
hormones in growth
hormones in reproduction
luteinizing hormone (LH)
Follicle stimulating hormone (FSH)
small amount of hormone produces significant effects due to gain of signal
Negative feedback control
when the released hormone can go back up to the hypothalamus and pituitary to stop production of the tropic hormone
Adrenal axis negative feedback
Hypothalamus secretes CRH
CRH acts on anterior pituitary
anterior pituitary secretes ACTH
ACTH goes to adrenals
adrenals produce cortisol
cortisol tells hypothalamus and pituitary to stop producing
less common than negative feedback
when production of the final hormone stimulates more hormone to be produced.
Seen in ovulation (estrogen makes more estrogen and progesterone)
Hormone patterns change based on light rhythms as well as negative feedback
Interface between ES and NS.
Produces peptides and amines to influence pituitary
Part of diencephalon, floor of third ventricle, connected to hypophysis.
made up of anterior (adenohypophysis) and posterior (neurohypophysis).
anterior made from pouch of pharyngeal mucosa
posterior made from outgrowth of hypothalamus. Remains connected by stalk.
direct axonal connection.
Hormones secreted by posterior pituitary are synthesized by hypothalamus, carried by axon, posterior secretes into veins, then systemic. Called neurocrines. Vasopressin (ADH) and Oxytocin. Peptide hormones. Direct hormones.
Secreted into blood, cause response not more hormone.
released by posterior pituitary.
contraction of smooth muscle (mammary gland and uterus)
released by posterior pituitary.
conservation of water, increased blood pressure.
disorder of water metabolism characterized by polyuria, dilute urine and polydipsia.
caused by defective secretion of ADH (Central) or renal lack of response to ADH (nephrogenic)
partial or complete
Central diabetes insipidus
lack of secretion of ADH causes water disorder with dilute urine and dehydration.
nephrogenic diabetes insipidus
when kidneys don't respond to ADH, leads to dehydration and dilute urine
Syndrome of inappropriate antidiuretic hormone secretion (SIADH)
hypersecretion of vasopressin (ADH).
often neoplastic or drug reaction
hyponatremia (low NA+) because body is SO dilute.
concentrated urine, over-hydration
portal system links anterior hypophysis with hypothalamus.
hypothalamic releasing factors stimulate endocrine cells within anterior pituitary to secrete hormones into capillary system
capillary systems in hypothalamus and in anterior pituitary that coalesce and drain into systemic veins.
Hypothalamic releasing hormones (7)
released from hypothalamus into portal system, stimulate anterior pituitary to secrete hormones into capillaries
Thyrotropin-releasing hormone (TSH)
Gonadotropin releasing hormon (GnRH)
Growth hormone inhibiting hormone (GHIH)
Growth hormone releasing hormone (GHRH)
Corticotropin-releasing hormone (CRH)
Prolactin-releasing factor (PRF)
Prolactin-inhibiting hormone (dopamine) (PIH)
Anterior pituitary hormones (6)
all are peptide hormones. All are tropic except prolactin.
Growth hormone (somatotropin)
Thyroid stimulating hormone (TSH)
Follicle-stimulating hormone (FSH)
Lutenizing hormone (interstitial-cell-stimulating hormone) (LH or ICSH)
increased production of insulin by islet cell tumors
Opposite of diabetes mellitus (causes low glucose in blood and urine, lots of storage).
LOTS in ferrets
produced by alpha cells in islets of langerhans
increases blood glucose levels. (opposite of insulin. Action/reaction pair)
decreases glycogen synthesis, increases glycogenolysis and increases gluconeogenesis.
Stimulated by low glucose, Symp NS and Para NS,
INHIBITED BY SOMATOSTATIN
Glucagon and insulin
work together to keep blood glucose levels steady. After a meal, blood glucose is high, insulin released. Hours later, glucagon released.
extremely rare tumor of alpha cell of islets of langerhans causing increased secretion of glucagon
superficial necrolytic dermatitis (on feet and hock area), hyperglycemia
inhibitor of secretion of pancreatic hormones (insulin, glucagon, pancreatic polypeptide). inhibitor of growth hormone secretion, inhibitor of digestive process, decreasing absorption, secretion and motility.
secreted by D cells of pancreas, brain and GI tract.
Secretion stimulated by nutrients, neurotransmitters (ACH, epinephrine, norepinephrine)
tumor of delta cells of endocrine pancreas
extremely rare (bearded dragons).
anorexia, vomiting, hyperglycemia, anemia
secreted by F cells of endocrine pancreas.
effects in GI tract (not exactly sure how--inhibits pancreatic/gallbladder secretions,increases gastric emptying and motility)
secretion stimulated by intestinal hormones (CCK, Secretin, Gastrin), vagus, and ingestion of protein.
Inhibited by SOMATOSTATIN
Pancreatic polypeptide disease
pancreatic polypeptidomas are very rare. Pancreatic tumors can cause multiple hormone problems