Hormone vascular systems

In addition to its osmoregulatory function, HSA serves a transport function. Various metabolites travel throughout the vascular system predominantly bound to HSA. These include fatty acids, amino acids, steroid hormones and heavy metals (e.g. copper and zinc), as well as many drugs. 

Physiologists had postulated for a long time about the existence of a sodium excreting hormone to prevent Na overload and consequent deleterious effects of high blood pressure on the heart and vascular system. At least two such natriuretic factors have been described atrial or A-type and brain or B-type natriuretic factors. Structurally, the natriuretic factors are peptides with a cysteine-cysteine disulfide bridge creating a characteristic loop , this is illustrated by Figure 8.8. 

The other hormone of note synthesized by kidney is erythropoietin (EPO), a glycosylated peptide hormone (molecular weight approximately 50 000), which promotes red blood cell formation and is secreted in response to poor oxygen perfusion (hypoxia) of the kidney. This, along with the control of blood pressure via the RAA system illustrates the importance of the kidney in regulating aspects of the blood vascular system. Further details of EPO can be found in Chapter 5. 

Natriuretic Peptide Diuretics. Atrial natriuretic peptide (ANP). an endogenous diuretic, natriuretic, and vasodilator, is a peptide hormone primarily synthesized and stored hy atrial cardiocytes. and secreted hy the atria in response to mechanical stretch of the atria. ANP is also known as anarilide. CiijHnsNjoO.ijS-i atrial natriuretic factor (ANF) auricuiin cardionairin and alriopeptide. Its primary action Is in the kidney and the vascular system. 

When TSH contacts its receptor-sites located throughout the thyroid gland a series of enzymic reactions occur using tyrosine and iodine as substrates or raw materials to produce and/or release L-Thyroxine (T-4). This is then released into the vascular system so it can circulate. It should be noted that T-4 is an active form of thyroid hormone. 

The active T-4 circulating in the vascular system merges with receptors and triggers metabolic activity but when it reaches the liver it is changed into the more active thyroid hormone L-Triiodothyronine (T-3) by an enzyme called 5-deiodinase. T-3 is about 5 times more active than T-4. The newly formed T-3 is released into the vascular system where it may contact and merge with cellular receptors which initiates all the metabolic activity discussed earlier. 

Q3 Vasopressin is a small peptide hormone consisting of nine amino acids, most of which is synthesized in neurosecretory cells of the supraoptic nucleus of the hypothalamus. Small quantities are also produced in the neighbouring paraventricular nucleus. The hormone is transported down the axons of the neurosecretory cells via the infundibulum to the posterior pituitary, where it is stored until release into the blood is triggered by nerve impulses from the hypothalamus. Vasopressin is better known as antidiuretic hormone (ADH). The name vasopressin relates to its vasoconstrictor action, which increases pressure in the vascular system. This action was discovered before its effects on water retention were known. 

The drugs discus.sed in this chapter arc used for their action on the heart or other parts of the vascular system, to modify the total output of the heart or the distribution of blood to the circulatory system. These drugs are used in the treatment of angina, cardiac arrhythmias, hypertension, hyperlipidemias. and di.sorders of blood coagulation. This chapter also includes a discu.ssion of hypoglycemic agents, thyroid hormones, and antithyroid drugs. 

The synthesized or synthetic proteins previously discussed in terms of the genetic code are not necessarily the same as those that start out as nutritional or dietary proteins. However, digestive enzymes break down dietary proteins into the amino acid pool required for subsequent cell protein synthesis, as has been described. The proteins so synthesized variously become cellular structural components, enzymes and hormones, and blood plasma proteins. The latter are involved in cellular osmotic balances, that is, in ensuring a stable pressure difference across the cell walls. These blood proteins also transport substances through the vascular system, and assist in promoting inununity (Chaney, in Devlin, 1986, p. 1179ff). 

On the other hand, ER0 is expressed prominently, in testicular tissue, secretory epithelial cells of the prostate, in the vascular system and, apparently, in breast tumour cells. ER0 is also found in brain, bone, bladder and vascular epithelia, which have been seen responsive to classical hormone replacement therapy [59, 60, 61],... 

Thyroid Hormone Action within the Heart and Vascular System from Cellular to Hemodynamic Effects... 

Red clover contains isoflavones, compounds that are structurally similar to the human hormone estradiol and capable of binding to estrogen receptors (Umland et al. 2000). Some studies have indicated that red clover isoflavones have a greater affinity for the estrogen receptor P (found primarily in bone, brain, heart, and vascular system) than estrogen receptor a (found primarily in uterus, breast, ovaries, and adrenal glands) (Beck et al. 2005 Dornstauder et al. 2001). 

Mesenchymal stem cells in the tissue sheath serve as a reservoir for new DP cells. The DP determines the size of the anagen hair bulb, the duration of anagen and hair shaft diameter [20, 29, 30]. In adult hair, DP maintains the vascular system that provides the nutritional support and hormonal regulation required for hair growth [31]. 

The ability of transfer cells to move solutes in and out of the vascular system and their positioning at strategic locations (Gunning et al. 1968, Pate and Gunning 1972, Gunning and Pate 1974) suggests that transfer cells may play a role in controlling the flux and distribution of plant hormones via the xylem and phloem. 

Endogenous growth regulators may be translocated in the plant s vascular systems. This would seem to hold especially true for gibberellins and cytokinins, since activity has been detected in the xylem sap of many different herbaceous as well as woody species. Obviously these hormones are also exported from photosynthesizing leaves, as indicated by their presence in sieve tube sap. Although with less frequency, also auxin and ABA-like activity have been detected in both xylem and phloem sap (Table 3.1). 

SO the completed vascular system is ready at an early stage for translocation of metabolites from the scutellum to the embryo, and/or (if it occurs) for the transport of gibberellins synthesized at the node to the scutellum, whence they can be released. There is evidence, coming from the use of radioactive gibberellic acid, that this hormone can indeed be transported through the vascular strand of the scutellum [112]. 

---