Endocrine System -13.2 Flashcards
How many lobes does the pituitary gland have and what are they?
Anterior Pituitary and Posterior Pituitary
* It has two lobes
What connects the hypothalamus to the pituitary gland?
The pituitary stalk (infundibulum)
Why is the pituitary gland called the “master gland.”
It releases several trophic hormones - up to 8
What controls the pituitary gland?
The hypothalamus - via (releasing hormones and neurons through pituitary stalk)
Does the posterior pituitary produce hormones?
No, it is considered to be part of the nervous system - does not produce any hormones
- Releases and stores hormones (ADH and Oxytocin) that are produced in the hypothalamus - but are transferred through the neuronal axons
Does the anterior pituitary produce hormones?
Yes, it is a hormone synthesizing gland - produces up to 6 hormones
- hgh
- ACTH
- TSH
*FSH
*LH
*Prolactin
How is the anterior pituitary stimulated?
series of blood vessels (portal system) carries releasing hormones from hypothalamus to pituitary - hormones inhibit or stimulate the release of hormones from this gland
What does hGH released by the anterior pituitary do?
regulates growth, development, and metabolism
Cell division - bone and muscle growth
Is hGH a tropic hormone?
Yes, but it can have direct stimulation on some body tissue
What does hGH stimulate the liver to release?
growth factors
What physiological processes does hGH and growth factors affect?
- protein synthesis
*Cell division and growth - growth of cartilage, bone, and muscle
*Metabolic reaction and the release of fats stored in adipose tissue
What happens if large amounts of hGh is produced during childhood?
Gigantism
What happens if there is an insufficient production of hGH during childhood?
Dwarfism
What is acromegaly?
When someone reaches adulthood and skeletal growth is completed - and there is still an overproduction of hGH.
Can’t grow in height - bones and soft tissues widen
What caused Creutzfeldt - Jakob disease?
A child who received hGH treatment.
What did genetic engineering produce in 1985?
Synthetic hGH - gene that codes hGH is injected into bacteria - bacteria produces rapidly creating hGH
Describe the thyroid gland in regards to its location?
Located directly below larynx
Has two lobes - one on each side of the trachea
What is the primary affect of thyroxine (T4?)
To increase the rate at which the body metabolizes protein, fat, and carbohydrates for energy
Does thyroxine have a specific target organ?
No, it stimulates the cells of the heart, kidney, liver, and skeletal muscles to increase the rate of cellular respiration
Other than metabolism what other effects does thyroxine have?
It plays an important role in the growth and development of children - organizes various cells into the tissues and organs
What happens if thyroxine fails to develop properly in childhood?
Cretinism
What does an individual with cretinism look like?
They are stockier and shorter than the average child
Without hormonal injections early in life they will have developmental delays
What happens if there is an extremely low level of thyoxine produced?
Hypotyroidism
What happens to an adult with hypothyroidism?
*They feel tired
*Slow pulse rate and puffy skin
*Hair loss
*Gain weight
* Slow metabolism
What happens if there is an overproduction of thyroxine in an adult?
Hyperthyroidism
What happens to an adult with hyperthyroidism?
They have:
*anxiety
*insomnia
*heat tolerance
*irregular heart beat
*fast metabolism - lose weight
What is a severe state of hyperthyroidism?
Grave’s disease
What happens with Grave’s disease?
They bodies immune system attacks the thyroid
Produces swelling of muscles around the eyes - protrude affecting vision
How can hyperthyroidism be treated?
*Medication
*Removal of part of thyroid
*Irradiation of part of thyroid
What controls thyroxine secretion?
A negative feedback loop
What is the process of Thyroxine being produced from anterior pituitary?
- Anterior pituitary releases thyroid stimulating hormone - causes thyroid gland to secrete thyroxine
- Thyroxine levels rise - thyroxine feeds back to hypothalamus and anterior pituitary to stop releasingW TSH and therefore thyroxine
What does the thyroid require in order to make the thyroid hormones?
It requires iodine - short form of the for thyroxine - refers to four iodine molecules in the hormone
What if there is an insufficient amount of iodine in diet?
Thyroxine cannot be made - no signal to stop the secretion of TSH by the anterior pituitary
- Person would be tired, no energy, slow metabolism
What if there is a relentless stimulation of the thyroid gland?
Goitre - enlargement of the thyroid gland
What is calcium essential for?
Healthy teeth and skeletal development
* Plays a crucial role in blood clotting, nerve conduction, muscle contraction
What hormone in the blood regulates calcium levels?
Calcitonin
What happens when calcium levels in the blood rises?
Calcitonin stimulates the uptake of calcium by the bones
Reabsorption of calcium by the kidneys
What are parathyroid glands?
Four glands that are attached to the thyroid?
What hormone does the parathyroid glands produce?
A hormone called parathyroid hormones
What happens if there is a low amount of calcium in the blood?
The paraythorid gland will be stimulated and parathyroid hormone will be produced
What does parathyroid hormone do?
Raises blood calcium levels
- breakdown of bones to release clacium
*Reabsorption of calcium by kidneys from urine (activates vitamin D)
*Vitamin D stimulates the absorption of calcium from food by the intestines
