Endocrine

Endocrine & Nervous

• rely on release of chemicals
• share many chemical mssger 
• regulated primarily by -ve feedback 
• common goal: to preserve homeostasis by coordinating & regulating activities of other cells, tissues, organs, systems 

Hormone class

• peptide
• range from short polypeptide chain of aa to small proteins 
• water soluble = hydrophilic 
• cell surface receptor 
• insulin, glucagon, ACTH, PTH, TRH, GH
• steroid/lipid derivatives
• eicosanoid or cholesterol 
• lipophilic 
• + ic receptor 
• release by gonads, adrenal gland 
• estrogen, progesterone, corticosteroid 
• amino acid derivatives 
• tyrosine & tryptophan 
• TH
• catecholamine - EP, NE, dopamine
• Trp - melatonin 

Water-soluble hormone action

• act on receptor in PM
• receptor coupled via G protein to >1 IC 2nd mssger mediate target cell response
• Insulin, glucagon
• hormone + receptor + G protein 
• ATP to cAMP 
• open ion channel & activate enzymes
• GHIH
• hormone + receptor + G protein
• cAMP to AMP 
• reduced enzyme activity 
• OT/EP
• hormone + receptor + G protein
• open Ca channel & release of stored Ca from ER/sER
• Ca + calmodulin
• activates enzymes 

Lipid-soluble hormone action

• + receptor in cytosol/nucleus 
• activated receptor-hormone complex alters gene exp
• newly formed mRNA directs synthesis of specific proteins on ribosomes 
• new proteins alter cell's activity - metabolic activity & structure 

Hormone secretion

• neural 
• humoral - chemical changes in blood
• hormonal - other hormone 

Thyroid hormone production

• iodine ions actively transported into cytoplasm
• iodide to iodine & + tyrosine of thyroglobulin
• tyrosine + iodine = TH remain in thyroglobulin
• follicle cells remove thyroglobulin from follicle cavity by endocytosis
• thyroglobulin is broken down 
• releasing aa & TH to be recycled
• TH diffuse into bloodstream
• thyroid binding globulin transport TH molecule 

Thyroidectomy 

• low Ca, hypothyroidism if parathyroid gland affected 
• TH still high after surgery 
• continue release of stored TH
• take time to adjust/re-establish a balance 
• T4 half life = 1w

Gland	Hormone	Target	Function
Hypothalamus	TRH	Ant. pit.	TSH
	CRH		ACTH
	Gonadotropin RH		FSH LH
	GHRH GHIH - somatostatin		GH
	PRH PRIH - dopamine		PRL
	ADH	Post. pit.	ADH
	OXT		OXT
	SNS	Adrenal medulla	EP, NE
Ant. pit.	TSH	Thyroid	TH
	ACTH	Adrenal cortex	Stimulate hormone secretion
	FSH	Ovaries Testes	Promotes ovarian follicle development  Stimulate estrogen Promotes maturation of developing sperm
	LH	Ovaries Testes	Induces ovulation Secrete estrogen & progesterone Secrete androgen
	GH	Musculo- Skeletal Cartilage  Adipose Liver	Body growth  Metabolism  Lipolysis  Release FA into bloodstream Glycogenolysis  Release glucose into bloodstream Somatomedin/IGF synthesis
	PRL	Mammary	Milk production
	MSH	Skin	Melanocyte  Suppress appetite
Post. pit.	ADH	Kidney	Retain H2O  Decrease urination Vasoconstriction
	OXT	Uterus	Smooth muscle contraction Promote milk ejection
Thyroid follicle Parafollicular	Triiodothyronine T3	Most body cells	Metabolism, BMR Increase rate of O2 & energy consumption Increase HR Rise in BP Increased sensitivity to SNS RBC formation Accelerated bone mineral turnover
	Thyroxine T4
	Calcitonin	Kidney  GI Osteoclast	Increase Ca excretion Prevent Ca absorb Lower Ca  Suppress osteoclast activity
Parathyroid principal cell	PTH	Kidney  Bone  GI	Increase Ca reabsorption Ca release  Increased calcitriol Ca absorption
Adrenal cortex Zona granulosa  Zona fasciculata  Zona reticularis	Mineralocorticoid:  Aldosterone	Kidney	Decrease Na & H2O loss Renal reabsorption of Na
	Glucocorticoid: Cortisol	Liver Muscle  Adipose	Increase BG  Release aa Release lipid, lipolysis Increase resistance to stress Anti-inflammatory
	Androgen		Pubic hair  Sex drive
Adrenal medulla	EP	SNS
	NE
Pancreatic beta	Insulin	All body cells	Decrease BG  Promote glucose uptake Glycogenesis  Inhibit gluconeogenesis  Protein synthesis  TAG synthesis
Alpha	Glucagon	Liver  Muscle  Adipose	Increase BG  Gluconeogenesis  Glycogenolysis  Lipolysis
Delta	Somatostatin		Inhibin
Polypeptide	PP	Gallbladder	Inhibit contraction Pancreatic enzyme Control rate of nutrient absorption
Ovaries	Estrogen		Menstrual
	Progesterone		Menstrual  Maintain pregnancy  Feminine shape
Placenta	hCG	Uterus	Thicken lining support embryos
Testes	Testosterone	Muscle Vocal	Develop secondary characteristics
Pineal	Melatonin	Brain	Sleep-wake cycle
Thymus	Thymosin  Thymopoietin	T cell	T cell maturation