the endocrine system chapter 9. communication and control – slower and long lasting through...
TRANSCRIPT
The Endocrine System
Chapter 9
Communication and Control – slower and long lasting through hormones – chemical messages – that effect a target organ
Diseases (tumors) influence by: Hyposecretion – too little secretion Hypersecretion –two much secretion
All organs are glands: Exocrine – secrete products into ducts Endocrine – ductless glands Heterocrine Gland - Both (pancreas)
Origin Of Hormones
Hormones affects target cells Secreted by endocrine glands Secreted by neurons (neuro-hormones) -
neurosecretory cells Secreted by individual cells or tissues (Growth
Factors, prostaglandins, histamine)
Chemical Nature of Hormones
Derived from cholesterol
Derived from amino acids
Derived from fatty acids
Protein Hormones Second Messenger Hypotheses Cause specific affects on target
organs only Hormone binds to specialized
receptor – “first messenger” Second Messenger is Cyclic
Adenosine MonoPhosphate (cAMP)
The bonding of the hormone activates activates a G4 protein, which in turn activates adenylate cyclase (enzyme) to react with ATP to produce cAMP
Steroid Hormones Small – lipid soluble
Hormones Pass directly through the
cell membrane of target organs
Go to nucleus, interact with DNA to allow transcription of certain proteins
Prostaglandins
PG’s - tissue hormone – produced on a tissue and acts on nearby cells
Three groups PGA, PGE, PGF Might have a role in asthma, blood pressure
disorders, and ulcers
Negative Feedback
Reverses a change in a body condition Insulin – high blood-sugar content after a meal,
pancreas secretes insulin to move blood-sugar into cells, thus decreasing levels
Other types of Negative Feedback
Positive Feedback
More Uncommon than negative feedback Amplify changes rather than reverse them Labor – the contractions are amplified through
hormone control
Pituitary Gland Gland in hind brain about the size of a pea Anterior (adrenohypophysis)- gland / Posterior
(neurohypophysis) - nervous
Anterior (adrenohypophysis)- gland - hypothalamin releasing hormones get anterior to release hormones
Posterior (neurohypophysis) - nervous - nerve endings from hypothalamus cause hormones to be released
Hormones of Anterior Pituitary Tropic Hormones – Stimulates another endocrine gland to grow and
secrete its hormone
ANTERIOR GLAND - TROPIC TSH - (thyroid-stimulating) Growth and secretion of the thyroid ACTH - (adenocorticotropic) Growth of Adrenal cortex and
secretions FSH - (follicle stimulating) Growth and development of
Ovarian Follicles - providers of ova (eggs), release of estrogen/progesterone
LH - (Luteinizing) Control ovulation - maturation and bursting of follicle - males - interstitial cells
ICSH - (Interstitial cell)Testosterone secretion of testes
MSH - (melanin stimulating hormone) - synthesizes and spreads melanin - pigment
GH - (Growth Hormone) -stimulates growth by protein anabolism (building) - fat and glucose catabolism - enhances the movement of Amino acids across cell membrane Insufficient GH - dwarfism Oversecretion - giagntism
Prolactin - (lactogenic) - stimulates milk production, in males excess may decrease sex hormones
Posterior Pituitary Hormones
ADH- retention of water by kidneys (diuretic - loss of water by kidneys)- maintained by osmoreceptors in the brain
Oxytocin - stimulates uterine contraction - positive feedback
Thyroid Gland ---Parathyroid Gland Located in the neck, below the
larynx Thyroxin (T4 - four atoms of
iodine - accelerates metabolism Calcitonin - decreases blood
calcium, puts calcium into bones
Triiodothyronine (T3 three atoms of iodine) -energy for metabolism - five times as potent as thyroxin
Small (usually 4) found on the back of the thyroid
Increases Blood Calcium - breaks down bone
Adrenal Glands
Adrenal Glands - Lie on top of the kidneysTwo separate endocrine glands the adrenal cortex and
the adrenal medulla
ADRENAL GLANDS CORTEX Glucocorticoids - maintain
blood pressure, sugar, stress - cortisol
Mineralocorticoids - increase blood sodium, decrease blood potassium
sex hormones - small amount secreted, female converted to estrigens
Medulla Produces epinephrine and
norepinephrine for stress response - sympathetic inervation
The effects include increase heart rate, breathing rate, and all assoisiated sympahtetic responses
Pancreatic Islets/ Islets of Langerhans Alpha cells = glucagon, Beta cells = insulin
Female and Male Sex Hormones Ovaries – female, Testis - male Female characteristics and fertility - release of
estrogen and progesterone Male - secretes testosterone - interstitial cells -
controls male sexual development
PLACENTA Temporary endocrine gland secretes choriongonadotropin hormone - maintains corpus luteum - high in
urine = pregnancy PINEAL Small pine-coned shaped gland at the roof of the third ventricle of the brain Also called third eye – responds to senses Produces melatonin inhibits ovarian activity influences menstrual cycle biorhythms
HEARTAtrial Natriuretic Hormone – secreted by the walls of
the atria – regulates fluid and electrolytes THYMUS
Located in mediastinum. Has cortex and medulla Houses lymphocytes secretes thymosin - immune regulator