The Pituitary Gland - Structure - Vasculature - TeachMeAnatomy
You have your hypothalamus and pituitary gland to thank. Read about 3D products and resources for your anatomy and physiology course!. Conklin JL. A histochemical study of mucoid cells in the pars distalis of the human hypophysis. Anat Rec. Jan;(1)– [PubMed]; Daniel PM. In this article, we shall look at the anatomy of the pituitary gland – its The release of hormones is under the control of the hypothalamus, which.
The Pituitary Gland
The posterior pituitary gland comprises nerve cells. The structure of the pituitary gland is shown in figure 2.
- Relationship Between Hypothalamus and Pituitary Gland
Posterior pituitary secretes the hormones produced in the hypothalamus. The secretions of the other endocrine glands are regulated by the hormones secreted by the pituitary gland. Therefore, the pituitary gland is called the master gland of the body.
It regulates the secretion of hormones from the adrenal gland, thyroid glandhypothalamus, thymuspineal gland, pancreas, and gonads. Through these hormones, growth, development, metabolismblood pressure, sexual maturation, and reproduction are controlled.
Relationship Between Hypothalamus and Pituitary Gland Vascular Connection Hypothalamus is located below the thalamus whereas pituitary gland is located below the hypothalamus. The pituitary gland is attached to the hypothalamus by a stalk.
Hypothalamus is connected to the both lobes of the pituitary gland.
It connects to the anterior pituitary gland by means of a portal blood system. Therefore, the communication between hypothalamus and anterior pituitary gland occurs via chemical signals stimulating and inhibiting hormones. Those chemical signals are produced by the neurosecretory cells in the hypothalamus. They are released to a capillary network called primary plexus in order to be transported through the hypophyseal portal veins to a second capillary network called secondary plexus.
The primary plexus, as well as the hypophyseal portal veins, belong to the infundibulum. The secondary plexus belongs to the anterior pituitary.
The Hypothalamus and Pituitary Glands
The anterior pituitary complex is shown in figure 3. Anterior Pituitary Complex Neuronal Connection Some neurosecretory cells expand a short distance from the hypothalamus to the posterior pituitary through the infundibulum. The hormones produced by those neurosecretory cells are stored in vesicles and transported through the axons.
The storage of those hormones occurs at the axon terminals at the posterior pituitary. When the neurosecretory cells are stimulated, the hormones in the vesicles are released to the capillary network in the posterior pituitary.
The Hypothalamus and Pituitary Glands
The posterior pituitary complex is shown in figure 4. Posterior Pituitary Complex Due to the connection between the hypothalamus and the two lobes of the pituitary gland, the pituitary gland is involved in the storage and the release of hormones produced by the hypothalamus into the bloodstream.
In many mammals, there is also an intermediate lobe pars intermedia between the anterior and posterior pituitary. A key to understanding the endocrine relationship between hypothalamus and anterior pituitary is to appreciate the vascular connections between these organs. As will be emphasized in later sections, secretion of hormones from the anterior pituitary is under strict control by hypothalamic hormones.
These hypothalamic hormones reach the anterior pituitary through the following route: A branch of the hypophyseal artery ramifies into a capillary bed in the lower hypothalamus, and hypothalmic hormones destined for the anterior pituitary are secreted into that capillary blood.
Relationship Between Hypothalamus and Pituitary Gland | Definition, Anatomy, Physiology
Blood from those capillaries drains into hypothalamic-hypophyseal portal veins. Portal veins are defined as veins between two capillary beds; the hypothalamic-hypophyseal portal veins branch again into another series of capillaries within the anterior pituitary.
Capillaries within the anterior pituitary, which carry hormones secreted by that gland, coalesce into veins that drain into the systemic venous blood. Those veins also collect capillary blood from the posterior pituitary gland.2-Minute Neuroscience: Hypothalamus & Pituitary Gland
This pattern of vascular connections is presented diagramatically below. Note also the hypothalamic-hypophyseal portal vessels in the image of a real pituitary gland seen above.
The utility of this unconventional vascular system is that minute quantities of hypothalamic hormones are carried in a concentrated form directly to their target cells in the anterior pituitary, and are not diluted out in the systemic circulation.