More hormones

milk production

• Different receptors for the hormone
• Different signal transduction pathways
• Different proteins for carrying out the response
• A hormone can also have different effects in different species

endocrine glands

endocrine pathway

loop inhibits a response by reducing the initial stimulus

many hormonal pathways involved in homeostasis

are antagonistic hormones that help maintain glucose homeostasis

has clusters of endocrine cells called islets of Langerhans with alpha cells that produce glucagon and beta cells that produce insulin

• reduces by
• Promoting the cellular uptake of glucose (in most tissues except the brain)
• Slowing glycogen breakdown in the liver
• Promoting fat storage

• increases by
• Stimulating conversion of glycogen to glucose in the liver
• Stimulating breakdown of fat and protein into glucose

an autoimmune disorder in which the immune system destroys pancreatic beta cells

involves insulin deficiency or reduced response of target cells due to change in insulin receptors

• Peripheral neuropathy: diabetes damages the nerves (damage can occur to the foot and not be detected)
• Wounds: Diabetes affects circulation reducing the body’s ability to heal when damage occurs
• Infections: Diabietes slows the body’s response to infection
• –Antibody response is slow in type 1.
• –Poor circulation slows
• Nephropathy: kidney disease (affects proteins that are involved in wound healing)
• Retinopathy: eye disease/blindness

By 2020 Diabetes will cost the US $500 Billion/year–Half the population is projected to be diabetic or pre-diabetic

• A brain hormone stimulates release of ecdysone from the prothoracic glands
• Juvenile hormone promotes retention of larval characteristics
• Ecdysone promotes molting (in the presence of juvenile hormone) and development (in the absence of juvenile hormone) of adult characteristics

information from the nervous system and initiates responses through the endocrine system

the posterior pituitary and anterior pituitary

• Oxytocin induces uterine contractions and the release of milk
• Suckling sends a message to the hypothalamus via the nervous system to release oxytocin, which further stimulates the milk glands
• This is an example of positive feedback, where the stimulus leads to an even greater response

enhances water reabsorption in the kidneys

regulates the function of endocrine cells or glands

• Thyroid-stimulating hormone (TSH)
• Follicle-stimulating hormone (FSH)
• Luteinizing hormone (LH)
• Adrenocorticotropic hormone (ACTH)

Nontropic hormones target nonendocrine tissues

• –Prolactin (PRL)
• Melanocyte-stimulating hormone (MSH)

Prolactin stimulates lactation in mammals but has diverse effects in different vertebrates

influences skin pigmentation in some vertebrates and fat metabolism in mammals

• secreted by the anterior pituitary gland and has tropic and nontropic actions
• It promotes growth directly and has diverse metabolic effects
• It stimulates production of growth factors
• An excess of GH can cause gigantism, while a lack of GH can cause dwarfism

the adrenal medulla (inner portion) and adrenal cortex (outer portion)

• The adrenal medulla secretes epinephrine (adrenaline) and norepinephrine (noradrenaline)
• These hormones are members of a class of compounds called catecholamines

• secreted in response to stress-activated impulses from the nervous system
• They mediate various fight-or-flight responses

• –Trigger the release of glucose and fatty acids into the blood
• Increase oxygen delivery to body cells
• Direct blood toward heart, brain, and skeletal muscles, and away from skin, digestive system, and kidneys

hypothalamus

• androgens
• estrogens
• and progestins
• All three sex hormones are found in both males and females, but in different amounts

androgens, mainly testosterone, which stimulate development and maintenance of the male reproductive system

most importantly estradiol, are responsible for maintenance of the female reproductive system and the development of female secondary sex characteristics

which include progesterone, are primarily involved in preparing and maintaining the uterus