Endocrine system part 2 Flashcards
Endocrine signalling
The hormone is secreted from cells, diffuses into the blood or carried to the target organ
Gap junctions
Provide channels between adjacent cells
Synaptic signalling
Found in the nervous system where neurotransmitters are released from a nerve ending and diffuse to receptors
Where is paracrine signalling important?
During embryological development where many growth factors are released from cells and stimulate other cells
In the gastrointestinal tract, gut hormones secreted from the enteroendocrine cells (EEC) interact with receptors on neighbouring epithelial cells
The activities of the pineal gland and the pituitary gland are controlled from regions of the
Hypothalamus
The thyroid gland affects
Cell metabolism
Key functions of the kidney
Produces the hormone that controls red blood cell production: Erythropoietin and converts vitamin D to its active form calcitroil
Role of the adrenal gland
The outer cortex secretes steroid hormones and the inner medulla secretes catecholamines
Hormones that carry information from the periphery to the CNS
Leptin
Thyroxine
Ghrelin
Secretin
Hormone secreting cell integrates information
Vasopressin
Thyrotropin-releasing hormone (TRH)
Aldosterone
Glucagon
Melatonin
Insulin
Main features of the pituitary gland
Hypothalamus
Infundibulum
Anterior pituitary
Pars intermedia
Posterior pituitary
Role of the infundibulum
Connects the pituitary gland to the hypothalamus
How is the anterior pituitary gland connected to the hypothalamus
Through a vascular portal system
How is the posterior pituitary gland and the hypothalamus linked
The posterior pituitary contains nerve fibres that originate in the hypothalamus
Role of the pars intermedia
In foetal and early life it secretes melanocyte-stimulating hormone that results in skin pigmentation. It regresses in adults and becomes filled with colloid
The median eminence
Lies adjacent to the infundibulum
It is one of the circumventricular organs found that lack a blood-brain barrier. This allows the secreted releasing hormones to enter the capillary network. The releasing hormones are then carried into the portal capillary plexus that delivers them to the anterior pituitary endocrine cells.
Neurons from the hypothalamic nuclei release their neurotransmitters (releasing hormones) into
the capillary plexus in the medium emimence
Relationship between hypothalamus, releasing hormone and anterior pituitary
Hypothalamic nuclei secrete releasing hormone into the median eminence from which they diffuse into the capillaries are carried into the anterior pituitary
Trophic hormone, gland hormone, anterior pituitary and gland hormone
The anterior pituitary stimulates the release of trophic hormone
Trophic hormone stimulates the secretory gland, which stimulates the gland hormone
What does TRH and TSH mean
Thyroid releasing hormone and thyroid stimulating hormone
Feedback control of thyroid gland activity
High centres stimulate the hypothalamus (body temperature), which stimulates the release of TRH, which stimulates the anterior pituitary, which stimulates the release of TSH, which stimulates the thyroid gland to release thyroxine.
TSH inhibits
The release of TRH which comes from the hypothalamus
Feedback control of adrenal cortical activity
Hypothalamus receives information about levels of stress. Hypothalamus stimulates the release of CRH, which stimulates the anterior pituitary, which stimulates the release of ACTH which stimulates the adrenal cortex to release cortisol
Feedback control of gonadal activity in males
The hypothalamus receives information related to sexual activity. This stimulates the release of GnRH, which stimulates the Anterior pituitary, which stimulates the release of FSH and LH, which stimulates the testes to release testosterone
Feedback control of gonadal activity in females
Hypothalamus receives information related to sexual activity. Hypothalamus stimulates the release of GnRH, which stimulates the anterior pituitary, which stimulates the release of FSH and LH, which stimulates the ovaries to release estrogen and progesterone
Feedback control of prolactin secretion
Hypothalamus inhibits and stimulates dopamine release, which inhibits the anterior pituitary which stimulates prolactin, which stimulates the mammary gland to stimulate suckling
How do hormones go from the hypothalamus to the target organs (via the posterior pituitary)
Nuerons from the hypothalamic nuclei release their hormones from their nerve endings in the PP.
They enter the posterior pituitary capillary bed and are carried from the gland in the venous blood
After passing through the right side of the heart and lungs, they enter the circulatory system and are carried to their target organs
Major features of the control of vasopressin release
Decreased arterial blood pressure is caused from hyperosmolality and decreased plasma volume, which stimulates the posterior pituitary to release vasopressin, which stimulates the arterioles to vasoconstrict and the kidneys to retain water
Control of oxytocin release during labour
Hypothalamus causes the posterior pituitary to release oxytocin which causes the uterus to contract
Control of oxytocin release during suckling
Hypothalamus causes the posterior pituitary to release oxytocin which causes the mammary gland to eject milk
What does suckling do
It stimulates sensory nerves that carry information to the brain
Thyroid hormones are transported into cells by
Membrane transport proteins; they do not diffuse into cells
Thyroid hormones affect virtually every cell in the body
True
Which hormones associated wit thyroid function can be measured in the plasma
Thyroid stimulating hormone (TSH)
T4
T3
Hypothyroidism
When thyroid hormones are elevated
Hyperthyroidism
When thyroid hormones are depressed
Features associated with hypothyroidism
Reproductive failure
Slow HR
Weakness/lethargy
Features associated with hyperthryoidism
Insomnia
Fast heart rate
Anxiety
Nervousness
