24 Questions
Which part of the hypothalamus produces peptides, including oxytocin and antidiuretic hormone?
Supraoptic and paraventricular nuclei
What is the function of the primary capillary plexus in the hypothalamic-hypophyseal system?
To transport hormones from the hypothalamus to the adenohypophysis
What is the role of the inferior hypophyseal artery in the hypothalamic-hypophyseal system?
To supply blood to the adenohypophysis
What is the primary function of oxytocin?
To stimulate uterine contractions during childbirth
Where are hormone-releasing and hormone-inhibiting factors stored in the hypothalamic-hypophyseal system?
Median eminence
What is the primary function of the neurohypophysis?
To store and release oxytocin and antidiuretic hormone
Which of the following is a function of the adenohypophysis?
Producing and secreting hormones that regulate various bodily functions
What is the primary function of receptors in hormone signaling?
To translate the signal from the environment into the 'cell language'
Which of the following hormones is involved in social bonding?
Oxytocin
What is the primary function of the neurohypophysis?
To store and release hormones produced by the hypothalamus
Which of the following is a characteristic of the thyroid gland?
It is a gland located in the neck that produces hormones that regulate metabolism
What is the role of vasopressin in the body?
To regulate blood pressure and water reabsorption in the kidneys
What is the term for the system that consists of individual endocrine cells scattered throughout the gastrointestinal tract?
Diffuse neuroendocrine system
What is the term for the connection between the hypothalamus and the pituitary gland?
Hypothalamo-hypophyseal system
What percentage of the hypophysis is composed of the Pars Distalis?
75%
Which hormone is produced by the Thyrotrophs in the Pars Distalis?
TSH
What is the effect of vasopressin on the body?
Water management and body secretion
What is the function of oxytocin on the myometrium and oviducts?
Contraction of muscles
What type of cells are present in the Pars Intermedia?
Basophilic cells
What is the function of the Neurohypophysis?
Neurosecretion
What is the result of changes in the distribution of circulating blood on vasopressin secretion?
Increased secretion
What type of cells are present in the Neurohypophysis?
All of the above
What is the hormone produced by the Corticotrophs in the Pars Distalis?
ACTH
What is the effect of estrogen on oxytocin?
Amplification of oxytocin
Study Notes
Endocrine System vs Nervous System
- The endocrine system produces hormones that act on target tissues, organs, or cells, while the nervous system transmits signals through neurons.
Endocrine System's Function and Organization
- The endocrine system consists of glands (pituitary, thyroid, parathyroid, suprarenal glands, pineal body) and clusters of endocrine cells (islets of Langerhans in the pancreas) and individual endocrine cells scattered among the epithelial lining of the gastrointestinal and respiratory tracts.
Hormones
- Hormones are chemical substances that act on target tissues, organs, or cells, and are translated into a cellular response through receptors.
- Hormones can be peptides, proteins, or glycoproteins produced by endocrine cells.
Hypophysis (Pituitary Gland)
- The hypophysis is a small gland (0.5g) located in the sella turcica of the sphenoid bone.
- It has two parts: neurohypophysis (includes pars nervosa, neural stalk, and median eminence) and adenohypophysis (includes pars distalis, pars intermedia, and pars tuberalis).
Hypothalamo-Hypophyseal System
- The hypothalamo-hypophyseal system consists of neurons in the hypothalamus that produce peptides that are stored in the neurohypophysis or released into the adenohypophysis.
- The system regulates various bodily functions, including water balance, social bonding, and hormone regulation.
Pars Distalis
- Pars distalis is the largest part of the adenohypophysis (75%) and consists of cords of epithelial cells, capillaries, and fibroblasts.
- There are five types of secretory cells in pars distalis, each producing a specific hormone (STH, GH, PRL, FSH, LH, TSH, and ACTH).
Pars Intermedia
- Pars intermedia is a small part of the adenohypophysis and consists of basophilic cells, blood capillaries, and fibroblasts.
- Corticotropic cells in pars intermedia produce peptide POMC, which is converted into ACTH, MSH, LPH, and endorphin.
Pars Tuberalis
- Pars tuberalis is a funnel-shaped region surrounding the infundibulum of neurohypophysis and consists of secretory cells, fibroblasts, and blood vessels.
- Gonadotropins are secreted by cells in pars tuberalis.
Neurohypophysis
- Neurohypophysis consists of unmyelinated axons of neurons, pituicytes, and capillaries.
- It stores and releases vasopressin (ADH) and oxytocin, which regulate water management and milk duct contraction, respectively.
Hormones of the Neurohypophysis
- Vasopressin (ADH) regulates water management in the body.
- Oxytocin regulates myofibroblast contraction of the milk ducts and contraction of the myometrium and oviducts.
This quiz covers the basics of the endocrine system, including its function, organization, and components such as the hypothalamo-hypophyseal system, thyroid, parathyroid, and adrenal glands. Test your knowledge of histology and embryology!
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