Lecture 3 Flashcards
Pituitary gland ( AKA hypophysis)
- Small gland located in bony cavity just below hypothalamus
- Thin stalk connects pituitary gland to hypothalamus
The pituitary gland consists of two anatomically and functionally distinct lobes
- Posterior pituitary
- Anterior pituitary
Posterior pituitary
- neurohypophysis
- composed of nervous tissue
Anterior pituitary
- adenohypophysis
- consists of glandular epithelial tissue
Release of hormones from both anterior and posterior pituitary is controlled by
hypothalamus
Posterior pituitary
- Along with hypothalamus forms neuroendocrine system
- Does not actually produce any hormones
- Stores and releases two small peptide hormones
Post. pituitary peptide hormones:
- Vasopressin (ADH)
- conserves water during urine formation - Oxytocin:
Stimulates uterine contraction during childbirth and milk ejection during breast-feeding
ADH and oxytocin stored in:
Herring bodies of the posterior pituitary gland
Exercise in the heat
Maintain plasma volume become critical homeostatic concern
Losing large amount of fluid through sweating
Blood to skin for cooling & to muscle to nourish working muscle
To maintain cardiac output, venous return must be adequate.
How?
- 1st ADH secreted due to osmoreceptor stimulus
- osmolarity increases
- ECF decreases
- arterial BP decreases
Anterior pituitary
Secretes six different peptide hormones that it produces itself
Trophic hormones:
- TSH
- Adrenocorticotrophic hormone (ACTH)
- FSH
- LH
- GH
Not a trophic hormone:
- prolactin (PRL)
Thyroid-stimulating hormone (TSH)
Stimulates secretion of thyroid hormone
Adrenocorticotropic hormone (ACTH)
Stimulates secretion of cortisol by adrenal cortex
Follicle-stimulating hormone (FSH)
In females, stimulates growth and development of ovarian follicles; promotes secretion of estrogen by ovaries
In males, required for sperm production
Luteinizing hormone (LH)
In females, responsible for ovulation and luteinization; regulates ovarian secretion of female sex hormones
In males, stimulates testosterone secretion
Growth hormone (GH)
Primary hormone responsible for regulating overall body growth; important in intermediary metabolism
Prolactin (PRL)
Enhances breast development and milk production in females
- only non-trophic hormone secreted from ant. pituitary gland
Ant. pituitary gland made up of two cell types
Acidophils
Basophils
Acidophils:
Somatotropes - GH
Mammotropes - prolactin
Basophils:
Tirotropes - TSH
Gonadotroped - FSH, LH
Corticotropes - ACTH
Hypothalamic releasing and inhibiting hormones help regulate
anterior pituitary hormone secretion
Two most important factors that regulate anterior pituitary hormone secretion
Hypothalamic hormones
Feedback by target-gland hormones
Vascular Link Between the Hypothalamus and Anterior Pituitary
Would you expect the [ ] of hypothalamic releasing and inhibiting hormones in a systemic venous blood sample to be higher, lower, or the same as the [ ] of these hormones in a sample of the hypothalamic-hypophyseal portal system?
Highest [ ] in portal system because secreted in a ‘closed’ system
