The Hypothalamus:
- Possess several nuclei responsible for producing hormones
- Post: Paraventricular nucleus, supraoptic nucleus
- Ant: Arcuate nucleus, preoptic nucleus
- Regulates the secretions of the anterior pituitary
- Via hormones secreted into the blood
- Produces hormones secreted through the posterior pituitary
- Carried to posterior pituitary along axons
- Connected to the pituitary by way of the infundibulum
- Lacks a blood-brain barrier
Reulatory Hormones of the Hypothalamus
- Regulate the secretions of the anterior pituitary
- Releasing hormones
- Stimulate the production & secretion of specific anterior pituitary hormones
- Inhibiting hormones
- Block/deter the production & secretion of specific anterior pituitary hormones
- Hormones regulated by both releasing and inhibiting hormones
- PRL and GH
Pituitary Gland: Also called the hypophysis
- Connected to the hypothalamus via the infundibulum
- Has two three anatomically and functionally distinct lobes
- Anterior pituitary (glandular)
- Intermediate lobe
- Posterior pituitary (neural)
- Hormones released by the pituitary gland are directly controlled by the hypothalamus
- Anterior pituitary (vascular link)
- Posterior pituitary (neural pathway)
Posterior Pituitary:
- Neurosecretory neuron cell bodies located in the hypothalamus
- Supraoptic & paraventricular nuclei
- Synthesize vasopressin (ADH) and oxytocin
- Axons from these neurons travel to the posterior pituitary
- Hormones are stored in their axon terminals located within the posterior pituitary
until stimulated for release
- Cells within each nuclei can make either vasopressin or oxytocin, but not both
Hormones of the Posterior Pituitary:
- Oxytocin: Milk ejection/letdown - causes the movement ("let down") of mammary milk
into the subareolar sinuses
- Uterine contraction: Stimulates uterine contraction / inhibited by elevated blood
progesterone levels
, - Secreted during menses to aid in the expulsion of uterine epithelium
- Secreted during sexual intercourse to aid the movement of sperm through the
uterus
- Social behavior: Invokes feelings of contentment, reduced anxiety, calmness and security
in the company of a spouse or significant other
- Vasopressin (aka antidiuretic hormone, ADH)
- Increases the reabsorption of water into the plasma, thereby reducing urine
production
- Vasoconstriction results in increased blood pressure
Anterior Pituitary: Different cell types produces specific hormones
- Somatotropes: Secrete growth hormone (GH)
- Thyrotropes: Secrete thyroid-stimulating hormone (TSH)
- Corticotropes: Secrete adrenocorticotrophic hormone (ACTH) and b-endorphin
- Lactotropes: Secrete prolactin (PRL)
- Gonadotropes: Secrete follicle-stimulating hormone (FSH) and luteinizing hormone (LH)
- Two factors regulate hormone release:
- Hypothalamic hormones
- Feedback by target-gland hormones
Tropic Hormones of the anterior Pituitary
- Anterior pituitary is often referred to as the master gland of the body
- In general, the function of the hormones of the ant. pituitary is to control growth,
metabolism, and reproduction
- Trophic hormones
- Follicle Stimulating Hormone (FSH) & Luteinizing Hormone (LH)
- Regulate hormone activity in the gonads
- Collectively called gonadotropins
- Thyroid Stimulating Hormone (TSH)
- Regulates hormone secretion of the thyroid
- Adrenocorticotropic (ACTH)
- Regulates hormone production and secretion of the adrenal cortex
- Growth Hormone (GH): AKA somatotropin
- Affects metabolism and regulates hormone production by the liver
Hormones of the anterior Pituitary:
- Hormones
- Prolactin (PRL): Controls milk production (♀) and plays a role in the immune response
(♀ & ♂)
- Melanocyte Stimulating Hormone (MSH)
- Stimulates the rate of melanin synthesis by melanocytes and the distribution of
melanocytes in the skin
- Little effect in humans; also produced in the intermediate lobe of the pituitary
- Possess several nuclei responsible for producing hormones
- Post: Paraventricular nucleus, supraoptic nucleus
- Ant: Arcuate nucleus, preoptic nucleus
- Regulates the secretions of the anterior pituitary
- Via hormones secreted into the blood
- Produces hormones secreted through the posterior pituitary
- Carried to posterior pituitary along axons
- Connected to the pituitary by way of the infundibulum
- Lacks a blood-brain barrier
Reulatory Hormones of the Hypothalamus
- Regulate the secretions of the anterior pituitary
- Releasing hormones
- Stimulate the production & secretion of specific anterior pituitary hormones
- Inhibiting hormones
- Block/deter the production & secretion of specific anterior pituitary hormones
- Hormones regulated by both releasing and inhibiting hormones
- PRL and GH
Pituitary Gland: Also called the hypophysis
- Connected to the hypothalamus via the infundibulum
- Has two three anatomically and functionally distinct lobes
- Anterior pituitary (glandular)
- Intermediate lobe
- Posterior pituitary (neural)
- Hormones released by the pituitary gland are directly controlled by the hypothalamus
- Anterior pituitary (vascular link)
- Posterior pituitary (neural pathway)
Posterior Pituitary:
- Neurosecretory neuron cell bodies located in the hypothalamus
- Supraoptic & paraventricular nuclei
- Synthesize vasopressin (ADH) and oxytocin
- Axons from these neurons travel to the posterior pituitary
- Hormones are stored in their axon terminals located within the posterior pituitary
until stimulated for release
- Cells within each nuclei can make either vasopressin or oxytocin, but not both
Hormones of the Posterior Pituitary:
- Oxytocin: Milk ejection/letdown - causes the movement ("let down") of mammary milk
into the subareolar sinuses
- Uterine contraction: Stimulates uterine contraction / inhibited by elevated blood
progesterone levels
, - Secreted during menses to aid in the expulsion of uterine epithelium
- Secreted during sexual intercourse to aid the movement of sperm through the
uterus
- Social behavior: Invokes feelings of contentment, reduced anxiety, calmness and security
in the company of a spouse or significant other
- Vasopressin (aka antidiuretic hormone, ADH)
- Increases the reabsorption of water into the plasma, thereby reducing urine
production
- Vasoconstriction results in increased blood pressure
Anterior Pituitary: Different cell types produces specific hormones
- Somatotropes: Secrete growth hormone (GH)
- Thyrotropes: Secrete thyroid-stimulating hormone (TSH)
- Corticotropes: Secrete adrenocorticotrophic hormone (ACTH) and b-endorphin
- Lactotropes: Secrete prolactin (PRL)
- Gonadotropes: Secrete follicle-stimulating hormone (FSH) and luteinizing hormone (LH)
- Two factors regulate hormone release:
- Hypothalamic hormones
- Feedback by target-gland hormones
Tropic Hormones of the anterior Pituitary
- Anterior pituitary is often referred to as the master gland of the body
- In general, the function of the hormones of the ant. pituitary is to control growth,
metabolism, and reproduction
- Trophic hormones
- Follicle Stimulating Hormone (FSH) & Luteinizing Hormone (LH)
- Regulate hormone activity in the gonads
- Collectively called gonadotropins
- Thyroid Stimulating Hormone (TSH)
- Regulates hormone secretion of the thyroid
- Adrenocorticotropic (ACTH)
- Regulates hormone production and secretion of the adrenal cortex
- Growth Hormone (GH): AKA somatotropin
- Affects metabolism and regulates hormone production by the liver
Hormones of the anterior Pituitary:
- Hormones
- Prolactin (PRL): Controls milk production (♀) and plays a role in the immune response
(♀ & ♂)
- Melanocyte Stimulating Hormone (MSH)
- Stimulates the rate of melanin synthesis by melanocytes and the distribution of
melanocytes in the skin
- Little effect in humans; also produced in the intermediate lobe of the pituitary
