Anatomy 18 - The Endocrine System Flashcards
What is the endocrine system
A system of ductless glands that regulate bodily function via hormones
What are the main functions of the endocrine system
It maintains homeostasis, it helps the body react to stress, it is a major regulator of growth and development and it controls physical and behavioural activities
How does it maintain homeostasis
By regulating activities such as the concentration of chemicals in body fluids and the metabolism of proteins, lipids and carbohydrates
What are the tissues/glands within the endocrine system known as
Endocrine glands
What do endocrine glands do
They secrete chemicals into extracellular space
What are the chemicals secreted by the glands called
Hormones
How is it determined which cells are acted on by specific hormones
Only cells with the compatible receptors will be affected by specific hormones
What are the three ways in which endocrine glands are stimulated
Hormonal, humoral and neural
What is hormonal stimulation
When the stimulation of a gland occurs through hormones being secreted from somewhere else e.g. the pituitary stimulating the thyroid
What is humoral stimulation
The stimulation of a target gland through the presence of a molecule within the bloodstream
What is neural stimulation
Stimulation of a gland via direct signals from the nervous system
What are the central glands of the endocrine system
The pineal and pituitary glands
What are the peripheral glands of the endocrine system
The thyroid, parathyroid, thymus, adrenal/suprarenal glands and the pancreas
Where is the pineal gland situated
In the roof of the 3rd ventricle
What are the cells within the pineal gland called
Pinealocytes
What is the major secretory product of the pineal gland
Melatonin
What is melatonin involved in
Regulating sleep
What is the pituitary gland split into
The anterior and posterior pituitary
What is the pineal gland involved in regulating
Day/night cycles
What is the anterior pituitary composed of
Glandular tissue
Function of the anterior pituitary
To manufacture and release hormones
Hormones released from where control secretion of hormones from the anterior pituitary
The ventral hypothalamus
Through what system is the secretion of hormones from the anterior pituitary controlled
The hypophyseal portal system
What is the posterior pituitary composed of
Neural tissue
Function of posterior pituitary
Acts as a storage area and releases neurohormones
Where are the neurohormones released by the posterior pituitary made
The hypothalamus
Where is the pituitary located
In the hypophyseal fossa of the sella turcia of the sphenoid bone
What takes up hormones released by the pituitary
The bloodstream
What hormones are secreted by the anterior pituitary
Growth hormone, thyroid stimulating hormone, adrenocorticotrophic hormone, follicle stimulating hormone, luteinising hormone and prolactin
What regulates growth hormone
Growth hormone releasing hormone and growth hormone inhibiting hormone
What does growth hormone target
The liver, muscle, bone and cartilage
What regulates thyroid stimulating hormone
Thyroid releasing hormone and feedback
What is thyroid regulating hormone involved in regulating
Metabolism
What regulated follicle stimulating hormone
Gonadotrophin-releasing hormone and feedback
What does follicle stimulating hormone target
The testes/ovaries
What does follicle stimulating hormone regulate
The development, growth, maturation and reproductive processes of the body
What occurs due to a lack of follicle stimulating hormone
Failure of sexual maturation
What is adrenocorticotrophic hormone regulated by
Corticotrophin-releasing hormone and feedback
What does adrenocorticotrophic hormone act on
The adrenal cortex
What causes the production of adrenocorticotrophic hormone
Stress
What does the release of adrenocorticotrophic hormone cause increased production of
Corticosteroids
What is luteinising hormone regulated by
GnRH and feedback
Where does luteinising hormone target
The ovaries/testes
What does luteinising hormone stimulate the production of
Testosterone, the development of the corpus luteum and causes ovulation
What does a lack of luteinising hormone cause
Failure of sexual maturation
What is prolactin regulated by
Prolactin releasing hormone and prolactin inhibiting hormone
Where does prolactin target
The mammary glands
What hormones does the posterior pituitary release
Oxytocin and antidiuretic hormone
What regulates oxytocin
The hypothalamus and also by uterine stretching and suckling
Where does oxytocin target
The uterus and breasts
What does oxytocin stimulate
Birth and milk production
What regulates ADH
The hypothalamus by the blood osmolarity and volume
Where does ADH target
The kidneys
What causes a release of ADH
The body being dehydrated
What secretes thyroid hormone
Follicle cells
Where does thyroid hormone effect
All cells except the brain, sleep, uterus and thyroid
What is the thyroid hormone involved in
The metabolism of carbohydrates, proteins and lipids
What do parafollicular cells secrete
Calcitonin
What is the function of calcitonin
To lower the level of Ca++ in the blood
What is the function of parathyroid hormone
To increase the level of Ca++ in the blood
What does the thymus secrete and what is it essential for
Peptide hormones and for normal development of T lymphocytes and the immune response
What is involved in the short term stress response
The adrenal medulla
What does the adrenal medulla cause
An increase in heart rate and blood pressure, it causes the liver to convert glycogen to glucose, causes the dilation of the bronchioles, causes an increase in alertness and metabolism
What does the pancreatic islets produce
Glucagon and insulin
What is glucagon involve in
The synthesis of alpha cells
What is insulin involve in
The synthesis of beta cells
What do beta cells cause
The blood sugar levels to be lowered
What do alpha cells cause
The blood sugar level to increase
What does the adrenal cortex synthesise
Corticosteroids
How many corticosteroids are produced by the adrenal cortex
24
What are corticosteroids synthesised from
Cholesterol
What are the three categories of corticosteroids
Mineralocorticoids, glucocorticoids and sex steroids
Function of mineralocorticoids
Control electrolyte balance
Function of glucocorticoids
Stimulate fat and protein catabolism and release fatty acids and glucose into the blood
What stimulates the secretion of glucocorticoids
Adrenocorticotropic hormone
What is involved in the long term stress response
The adrenal cortex
