The Pancreas, Hypothalamus, Pituitary and Growth Hormone Flashcards
Where are neurotransmitters and neural hormones produced?
In the cell body
Where do neurotransmitters and neural hormones travel?
Along the axon
Where are neurotransmitters and neural hormones stored?
In the axon terminals in vesicles and then releases
Where is the pituitary gland located?
At the base of the brain and attached to the hypothalamus
What does the hypothalamus control?
The secretion of pituitary hormones (when activated by neural input, the hypothalamus stimulates the pituitary gland to secrete hormones)
What do pituitary hormones stimulate?
Some stimulate target cells and some stimulate the secretion of hormones by other endocrine glands (in particular the anterior lobe)
How many parts are there to the pituitary gland?
2
What are the parts of the pituitary gland?
Anterior and posterior lobe
What is the posterior lobe of the pituitary gland made of?
Neural tissue
What is the posterior lobe of the pituitary gland connected to the hypothalamus by?
Neurons with cell bodies in the hypothalamus and axon terminals in the posterior pituitary capillary bed
What does the posterior lobe of the pituitary gland do?
Secrete hormones into the blood
Where are posterior pituitary hormones made and where do they travel?
Made in the hypothalamus (cell body of the neuron), travel down the axon and are stored at the axon endings until required (peptide hormones)
What communication does the hypothalamus use with the posterior lobe?
Neural communication
How does the hypothalamus use neural communication with the posterior lobe?
To release hormones into the blood (increase or decrease in frequency of action potentials leads to corresponding change in hormone release)
What hormones are released by the posterior pituitary gland?
Antidiuretic hormone and oxytocin
What does the antidiuretic hormone do?
Stimulates the kidneys to reabsorb water (the kidneys conserve water when the body dehydrates)
What does oxytocin do?
Stimulates the contraction of uterine muscles during child birth and milk release in breast feeding
What is an example of positive feedback?
Contraction of uterine muscles during child birth
What do the antidiuretic hormone and oxytocin have in common?
Both are peptide hormones made in the hypothalamus and stored in the posterior pituitary until required
How are the anterior lobe of the pituitary gland and the hypothalamus connected?
By blood vessels
Where are releasing hormones secreted?
Into capillaries
What do hypothalamic hormones do in the anterior lobe?
Stimulate or inhibit release of hormones from specific anterior pituitary cells
What is the stimulus for hypothalamus communication with the anterior pituitary?
Neural input within the hypothalamus
What does the hypothalamus do with regards to the anterior lobe?
Signals the anterior lobe. to release hormones by hormonal stimulation, secreting stored releasing (or inhibiting hormones)
What do the releasing or inhibiting hormones do?
Bind to the receptor on the membrane of a specific cell type and a specific peptide hormone is secreted
What does the growth hormone have direct effects on?
Muscle, liver and fat cells
How does the growth hormone directly effect muscle cells?
Stimulates protein synthesis (long term) and inhibits cellular uptake of glucose (short term)
How does the growth hormone directly effect liver cells?
Stimulates glucose synthesis (short term) which has the same effect as glucagon of increasing the blood glucose concentration
How does the growth hormone directly effect fat cells?
Increases triglyceride breakdown in adipose tissue (short term)
What are the indirect effects of the growth hormone?
Promotes the growth of bones, muscle and other tissues by causing release of somatomedin C, which promotes cell division (long term)
What does the growth hormone have a long term effect on?
Growth
What does the growth hormone have a short term effect on?
Metabolism
What is the pattern of growth hormone secretion over a day?
Growth hormone concentration has peaks and troughs but are highest when we are asleep
What is the pattern of growth hormone secretion over a lifetime?
Higher in children than adults, peaks during puberty and declines with age
What hormone does the hypothalamus release?
The releasing hormone
What does the releasing hormone do?
Travels through portal veins to the anterior pituitary gland
What does the anterior pituitary gland do?
Releases pituitary hormone
What does the pituitary hormone do?
Travels through the bloodstream to the target organ which is usually another endocrine gland
What does the target organ do?
Releases a hormone which causes an effect
What can the pituitary and releasing hormones do?
Feed back to the hypothalamus
What are the two neurons related to the growth hormone in the hypothalamus?
Somatostatin and GHRH (growth hormone releasing hormone)
What does the somatostatin neuron cause release of?
Growth hormone inhibiting hormone
What does the GHRH neuron cause release of?
Growth hormone release hormone
What happens in the anterior pituitary gland when GHRH or GHIH are received?
The growth hormone is released/inhibited and goes directly to the muscle and fat cells to cause direct effects or to the liver
What happens when the growth hormone is received by the liver?
Somatodenin C is released which has an indirect effect
