Chemical Coordination and Integration Flashcards
Endocrine System- Characteristics
- Glands lack ducts (Ductless glands)
- Glands release hormones into the blood directly
- Hormones are released in small quantities
What are the two groups of endocrine glands?
Lipid soluble and water soluble
Lipid soluble- Group I
Receptors are seen on the cytoplasm of the target cells
Example: Steroid hormones
Water soluble- Group II
Receptors are seen on the plasma membrane of target cells
Example- Protein hormones
Protein hormone- Mechanism
- Protein hormone binds to receptor on the target cell
- Conformational change occurs in receptor
- Activated H-R complex stimulates G-protein
- G protein stimulates membrane bound enzyme adenylate cyclase
- Adenylate cyclase catalyses the conversion of ATP—-> cyclic AMP (cAMP)
- cAMP stimulates protein kinase
- Protein kinase stimulates specific enzymes present in the target cell to perform specific metabolic activities
What conversion is catalysed by adenylate cyclase?
ATP —> cAMP
What does cAMP stimulate?
Protein kinase
What does protein kinase stimulate?
Protein kinase stimulates specific enzymes present in the target cell to perform specific metabolic activities
Steroid hormones- mechanism
- Steroid hormones are lipid soluble so they can easily diffuse through cell membranes
- Selective binding to receptors in cytoplasm
- H-R complex binds to specific genes and activates/inhibits them.
- Gene transcription is altered. Protein synthesis is altered. It stimulates or inhibits the enzymes that performs specific metabolic activities.
Hypothalamus- location
Lies on the undersurface of the brain between the thalamus and the pituitary gland
CRH- full form+ what gland is it released by + effect
Corticotropin releasing hormone
Released by the hypothalamus
Effect: Stimulates adrenocorticotropic hormone (ACTH) from anterior pituitary. ACTH then stimulates adrenocorticosteroid hormones from adrenal cortex.
TRH- full form+ what gland is it released by + effect
Thryrotropin releasing hormone
Released by the hypothalamus
Effect: Stimulates release of thyroid stimulating hormone from anterior pituitary.
GnRH- full form+ what gland is it released by + effect
Gonadotropin releasing hormone
Released by the hypothalamus
Effect: Stimulates the release of gonadotropins (LH and FSH) from anterior pituitary
PRLH- full form+ what gland is it released by + effect
Prolactin releasing hormone
Released by the hypothalamus
Effect: Stimulates the release of prolactin from the anterior pituitary
GRH- full form+ what gland is it released by + effect
Growth releasing hormone
Released by the hypothalamus
Effect: Stimulates the release of growth hormones from anterior pituitary
Pituitary gland- location
It is located at the base of the hypothalamus and is connected by a stalk called infundibulum
How many hormones do the anterior and posterior lobes of the pituitary gland release respectively?
Anterior lobe- 6 hormones
Posterior lobe- 2 hormones
Name the hormones released by the anterior lobe of the pituitary gland
- TSH- Thyroid stimulating hormone
- ACTH- Adrenocorticopic hormone
- Gonadotropins
- PRL- Prolactin
- Lipotropins
- Growth hormone
TSH- full form+ what gland is it released by + effect
Thyroid stimulating hormone
It is released by the anterior lobe of the pituitary gland
Effect: Stimulates thyroid gland and helps secretion of thyroxine
ACTH- full form+ what gland is it released by + effect
Adrenocorticotropic hormone
Released by the anterior lobe of the pituitary gland
Effect: Stimulates growth of adrenal gland and helps secretion of hormones of adrenal gland
Gonadotropins: what gland is it released by + effect
Released by the anterior lobe of the pituitary gland
Effect: Stimulates gonadial activities and helps secretion of LH and FSH
PRL- full form+ what gland is it released by + effect
Prolactin releasing hormone
Released by the anterior lobe of the pituitary gland
Effect: Helps in maintaining pregnancy, enlargement of breasts during pregnancy to facilitate lactation
Lipotropins: what gland is it released by + effect
Released by the anterior lobe of the pituitary gland
Effect: Stimulates release of fatty acids from stored body fat
GH- full form+ what gland is it released by + effect
Growth hormone
Released by the anterior lobe of the pituitary gland
Effect: Stimulates body growth and metabolism
Name the hormones released by the posterior lobe of the pituitary gland
- Oxytocin
- ADH- Antidiuretic hormone/vasopressin