endocrinology
DESCRIPTION
ENDOCRINOLOGY. The Endocrine Glands & their Hormones. Basic principles in hormone actions: Many effects of one hormone are antagonized by another hormone This helps maintain HOMEOSTASIS. The Endocrine Glands & their Hormones. Pineal Gland. -Main hormone secreted MELATONIN - PowerPoint PPT PresentationTRANSCRIPT
ENDOCRINOLOGY
The Endocrine Glands & their Hormones
Basic principles in hormone actions:
Many effects of one hormone areantagonized by another hormone
This helps maintain HOMEOSTASIS
The Endocrine Glands & their Hormones
Pineal Gland
-Main hormone secretedMELATONIN
-Role Melatonin
--Mammals : Regulate reproductive activity in response to environmental light cyclese.g. Some mammals mate in summer (lot of light), while others mate in winter (low light).
The Endocrine Glands & their Hormones
Thyroid Gland
-Produces 3 main hormones
-Triiodothyronine (T3)-Thyroxine (T4)
Regulate body metabolism and areimportant in bone growth and maturationof the brain-Congenital lack of thyroid hormones:
Cretinism.-Calcitonin
Acts by reducing calcium levels
The Endocrine Glands & their Hormones
Parathyroid Gland
-Parathyroid Hormone
Raises Blood Calcium
(antagonize Calcitonin)
This hormone acts on bone, kidneyand the gut
The Endocrine Glands & their Hormones
Thymus Gland
-Thymosin : Stimulates the production of Lymphocytes
-Thymostatin : Inhibits the production of Lymphocytes
Thymus : Important for the neonatalproduction of antibodies
Thymus : Gland being at the centerof endocrine, neural, and immunesystems
The Endocrine Glands & their Hormones
Heart
-Granular cells in the heart musclesecrete Atrial Natriuretic Factor (ANF)
..ANF : Regulates blood pressure,blood volume, and excretionof water, sodium andpotassium
..ANF : Also a neuropeptide in the brain
The Endocrine Glands & their Hormones
Gastrointestinal Hormones
-The mucosa of the GI tract secretes a dozen PEPTIDE hormones3 most important:1. Secretin : Secreted in the small intestine
Stimulates the secretion ofpancreatic bicarbonate and hasother functions on digestion
2. Gastrin: Secreted in the walls of stomachStimulate hydrochloric acid secretionstimulate pancreatic enzyme secretion
3. Cholecystokinin : Secreted in the small intestineStimulate gall bladder contractionStimulate pancreatic enzyme secretion
The Endocrine Glands & their Hormones
Pancreas
Endocrine cells in the pancreas secrete2 major types of hormones
1. Insulin : Secreted in response to increase in blood glucose levels ;So insulin LOWERS glucose levels byINCREASING glucose UPTAKE in cellswhere it is stored as glycogen.2. Glucagon : Increases blood glucoselevels by stimulating the conversionof glycogen to glucose in the liver.
A parte : Insulin & Diabetes
Insulin & Diabetes
Diabetes : Hyperglycemia, ie. Elevated Blood Sugar
2 Types : The distinction is based uponwhether the blood sugar problem iscaused by insulin deficiency (Type 1)or insulin resistance (Type 2)
Type 1- Insulin Deficiency : There is notenough insulin produced by the pancreasso the patient must inject insulin on a dailybasis
Type 2 - Insulin Resistance : There is plenty ofinsulin but the cells of the body are resistantto its action so, increase in blood sugarThis form is controlled by a strict diet
The Endocrine Glands & their Hormones
Adrenal Glands
2 parts : Medulla & Cortex
Adrenal Cortex : 3 categories of steroidhormones
1. Mineralocorticoids2. Glucocorticoids3. Sex Steroids
Adrenal Medulla1. Adrenaline2. Noradrenaline
The Endocrine Glands & their Hormones
Adrenal Cortex
If there is a sodium deprivation,Aldosterone is secreted and actsto increase reabsorption ofsodium ions (NA+) in the kidneyssalivary glands, and sweat glands.
Stress Hormone, converts storedproteins to carbohydrate during stress.Antiinflammatory andImmunosuppressive functions.
Androgen
Estrogen
Influence sexual differentiationand bodily changes during puberty
The Endocrine Glands & their Hormones
Adrenal Medulla
Adrenaline : Released followingstress due to environmental extremes; Increases heartrate and blood glucose levelsso, increases the amount of workthe muscles can do (FLIGHT)
Noradrenaline : As Adrenaline, act as a NTin the brainPeriphery; increase blood pressureand constrict blood vessels(noradrenaline, stress, and heart disease…)
The Endocrine Glands & their Hormones
Gonads ; Testes
The male gonads : produces Androgens
Primary androgen = TESTOSTERONEOther androgen : Dihydrotestosterone
Androstenedione
Testosterone : Important for masculinizationControl of sperm productionDevelopment of male sexualcharacteristicsActivation of sexual and aggressive behaviors
The Endocrine Glands & their Hormones
Gonads ; Ovaries
2 major classes of hormonesESTROGENSPROGESTINS
Primary ESTROGEN : Estradiolothers : Estriol
EstroneSynthetic estrogens : Birth control pillsEstrogens : -Development of sexual
characteristics at puberty -Influence metabolic rate -Influence sexual and maternal behavior
The Endocrine Glands & their Hormones
Gonads ; Ovaries
PROGESTIN : Progesterone
-Stimulates breast and uterine enlargement at puberty & during menstrual cycle-Maintains pregnancy (inhibits menstrualcycle during pregnancy)
Other hormone released at the end ofpregnancy : RelaxinActs to prepare the birth canal.
Estrogen and Progesterone act in synergy.
The Endocrine Glands & their Hormones
Placenta
-Hormones secreted by the fertilized egg(Used in pregnancy tests)
Human Chorionic Gonadotropin (HCG)Act by keeping progesterone high at thebeginning of a pregnancy
Human Placental Lactogen (HPL)Stimulates the mammary glands to beginto secrete milk
PART II
The Pituitary Gland & its Hormone
Also calledthe HYPOPHYSIS
The Pituitary Gland & its Hormone
-Attached to the HYPOTHALAMUS
-Secretion of the pituitary hormones is regulated by hypothalamus
-HYPOTHALAMIC-PITUITARY connection
The Pituitary Gland & its Hormone
ANATOMY
-3 parts
--> Anterior Lobe-pars distalis
--> Intermediate Lobe-pars intermedia
--> Posterior Lobe-pars nervosa (“neural” cells)direct extensionof the hypothalamus
AD
EN
Oh
ypo
ph
ysisN
EU
RO
hyp
op
hysis
The Pituitary Gland & its Hormone
Attaches the hypothalamus to thepituitary. Also calledthe Infundibulum
Neurohypophysis
-Neuroscretory Cells -Paraventricular nucleus (PVN) -Supraoptic nucleus (SON)
-Hormones secreted
-OXYTOCIN-VASOPRESSIN
PVN SON
AXONS
The Pituitary Gland & its Hormone
Attaches the hypothalamus to thepituitary. Also calledthe Infundibulum
Neurohypophysis
PVN SON
AXONS
OXYTOCIN & VASOPRESSIN-Are really HYPOTHALAMIC hormones
-OXYTOCIN :
2 main functions
--> promotes uterine contractions --> stimulates milk ejection from mammary glands during lactation
-VASOPRESIN :
--> Antidiuretic hormone --> Raises blood pressure --> promotes water reabsorption by kidneys --> centrally : may promote memory
- Binding proteins for both oxytocin & vasopressin
--> Neurophysins
The Pituitary Gland & its Hormone
Attaches the hypothalamus to thepituitary. Also calledthe Infundibulum
Neurohypophysis
PVN SON
AXONS
The Pituitary Gland & its Hormone
Attaches the hypothalamus to thepituitary. Also calledthe Infundibulum
Adenohypophysis
AXONS
ADENOHYPOPHYSIS (ANTERIOR)
Mechanism for release of hormones
True endocrine gland because release hormone in the bloodstream(hypophysal portal system)
The Pituitary Gland & its Hormone
Median eminence
1. Neurosecretory cells of the hypothalamus release their hormones at the median eminence
2. Hormones circulate in bloodstream
3. Carried to the adenohypophysis
4. Stimulates secretion of other hormones from the adenophysis
5. These hormones are then released in the bloodstream to reach their target cells.
The Pituitary Gland & its Hormone
Attaches the hypothalamus to thepituitary. Also calledthe Infundibulum
Adenohypophysis
AXONS
Adenohypophysis : 6 hormones
1. Growth Hormone (GH) (also called ‘somatotropin’) …’tropic’=stimulating effect
GH = promotes growth in almost all body cells
A lot of attention for degenerativedisease…..
-Alzheimer-Parkinson-Anti-Aging
etc.
The Pituitary Gland & its Hormone
Attaches the hypothalamus to thepituitary. Also calledthe Infundibulum
Adenohypophysis
AXONS
Adenohypophysis : 6 hormones
2. Adrenocorticotropic HormoneACTH
Role : Stimulates synthesis andrelease of glucocorticoidhormones
‘Hypothalamic-pituitary-adrenalaxis’
1970’s : Role of memory….little problems…..
The Pituitary Gland & its Hormone
Attaches the hypothalamus to thepituitary. Also calledthe Infundibulum
Adenohypophysis
AXONS
Adenohypophysis : 6 hormones
3. Thyroid Stimulating HormoneTSH
Role : Stimulates the synthesis andrelease of thyroxine (T4)and triiodochyronine (T3)from the thyroid.
The Pituitary Gland & its Hormone
Attaches the hypothalamus to thepituitary. Also calledthe Infundibulum
Adenohypophysis
AXONS
Adenohypophysis : 6 hormones3 last hormones= ….gonadotropic hormones
4. Follicle stimulating hormone (FSH)
Role : In both sexes, promotes thedevelopment of reproductivecells (gametes) and promotes secretion ofgonadal hormones
Males : stimulates sperm productionFemales : stimulates growth of
primary follicle of ovary
The Pituitary Gland & its Hormone
Attaches the hypothalamus to thepituitary. Also calledthe Infundibulum
Adenohypophysis
AXONS
Adenohypophysis : 6 hormones3 last hormones= ….gonadotropic hormones
5. Luteinizing hormone (LH)
Role :
Female : Stimulates ovulation and formation of progesterone- secreting cells
Males : Stimulates cells that secrete androgens (e.g. testosterone)
The Pituitary Gland & its Hormone
Attaches the hypothalamus to thepituitary. Also calledthe Infundibulum
Adenohypophysis
AXONS
Adenohypophysis : 6 hormones3 last hormones= ….gonadotropic hormones
6. Prolactin (PRL)
Role : Initiates milk synthesis inmammary glands
Other functions related to growth & parental behavior
Interaction with serotonin also(important in depression)
The Pituitary Gland & its Hormone
Attaches the hypothalamus to thepituitary. Also calledthe Infundibulum
Adenohypophysis
AXONS
Non traditional hormone from theadenohypophysis
--> beta-endorphin
Derivative from POMC
POMC : synthesized in the parsdistalis and pars intermedia
Broken down into ACTH, MSH &beta-endorphins by enzymes
The Pituitary Gland & its Hormone
Beta-Endorphin : Role to play in --> Analgesia--> Learning and Memory--> Psychiatric diseases--> Feeding, Thermoregulation,--> Blood pressure--> also called the ‘drug of the jogger’…..
The Pituitary Gland & its Hormone
Attaches the hypothalamus to thepituitary. Also calledthe Infundibulum
Pars Intermedia
AXONS
Pars Intermedia :
Not present in adult humans butpresent in fetal humans and mammals
Synthesize the hormone calledMelanocyte stimulating hormoneswhich acts in amphibian to changeskin color….
..