1. Endocrine System

2. Glands and Hormones
The Endocrine System consists of glands and tissues that secrete hormones
Endocrine Glands: ductless; secrete hormones directly into tissue fluid
Hormones: chemical signals that affect the behavior of other glands or tissues; each type has unique composition
Influence metabolism of cells, growth and development of body parts, and homeostasis

3. Categorize Hormones 2 classifications:
Peptide Hormones (proteins, glycoprotein, modified amino acids)
Steroid Hormones (lipids, estrogen, progesterone, testosterone)
Peptides: stay outside cell and directs activities within
Bind to receptor protein in plasma membrane and activate “second messenger”
Common second messengers found in many body cells include cyclic AMP (cAMP, made from ATP) and calcium
Steroids: have same four-carbon ring complex, but each has different side chains
Diffuse across plasma membrane and other cellular membranes
Bind to receptor proteins once inside cell

4. Hormone Release
Insulin release is controlled by negative feedback, hormonal control, and neural control
Release of hormones is controlled by different mechanisms:
Negative feedback controls hormone release
Hormone release controlled by actions of others
Hormone release controlled by nervous system
Release is usually controlled by a negative feedback system for the majority of hormones
Negative Feedback System: stimulus causes body response
Hormone release can also be controlled by certain stimulating/inhibiting hormones
Few instances where positive feedback controls release of hormones

5. Nervous System
The Nervous System plays a role in the Endocrine System; they work together to regulate the organs of the body
The Nervous System is an important controller of the Endocrine System
The brain can make appropriate adjustments to hormone secretion which ensures homeostasis; the endocrine system is involved in homeostasis

6. Hypothalamus & Pituitary Gland
Hypothalamus: regulates internal environment
Through autonomic system, helps control heartbeat/body temperature/water balance
Also controls glandular secretions of pituitary gland (hypophysis)
Pituitary Gland: attached to base of brain that consists of anterior and posterior lobes
Posterior Pituitary (Neurohypophysis)
Anterior Pituitary (Adrenohypophysis)

7. Hypothalamus
Oxytocin: other hormone made in hypothalamus, causes uterine contraction during childbirth and milk letdown when baby is nursing
Hypothalamic-releasing Hormones: one of many hormones produced by the hypothalamus that stimulates secretion of anterior pituitary hormone
Hypothalamic-inhibiting Hormones: one of many hormones produced by the hypothalamus that inhibits secretion of anterior pituitary hormone

8. Pituitary Gland
Posterior Pituitary: a portion of the pituitary gland connected by a stalk to the hypothalamus
Diabetes Insipidus: person produces copious amount of urine with a resultant loss of ions from blood
Deals with Posterior Pituitary
Antidiuretic Hormone (ADH): hormone released from pituitary lobe of pituitary gland that enhances water conservation by kidneys with Posterior Pituitary
Sometimes called Vasopressin

9. Thyroid and Parathyroid Glands
Thyroid Gland: large gland located in the neck, where it is attached to trachea just below larynx
Composed of a large number of follicles, each small spherical structure made of thyroid cells filled with triiodothyronine and thyroxine
Thyroid-Stimulating Hormone (TSH): hormone that causes thyroid to produce thyroxine
Parathyroid Gland: embedded in the posterior surface of the thyroid gland

10. Thyroid Gland
Myxedema: occurrence of hypothyroidism in adults; characterized by lethargy, weight gain, loss of hair, slower pulse rate, lowered body temperature, and thickness and puffiness of the skin
Hyperthyroidism: (oversecretion of thyroid hormone), thyroid gland is overactive, and a goiter forms (exophthalmic goiter), also be caused by thyroid tumor
Congenital Hypothyroidism: when thyroid fails to develop properly, individuals with this condition are short and stocky and have had extreme hypothyroidism (undersecretion of thyroid hormone)
Therapy can initiate growth, but unless treatment is begun within the first two months of life, mental retardation results
Thyroid hormones:
increase the metabolic rate
do not have a single target organ
stimulate all cells of the body to metabolize at a faster rate
more glucose is broken down, and more energy is utilized

11. Parathyroid Gland
Parathyroid Hormone (PTH): causes the blood phosphate level to decrease and the ionic blood calcium level to increase
Calcitonin: a hormone secreted by the thyroid gland when the blood calcium level rises, from the thyroid gland and the parathyroid gland and hormones, maintain the blood calcium level within the normal limits
Hypocalcemic Tetany: when insufficient parathyroid hormone production leads to a dramatic drop in the blood calcium level
In tetany, the body shakes from continuous muscle contraction. This effect is brought about by increased excitability of the nerves, which nerve impulses spontaneously and without rest. In severe cases, it is fatal.

12. Adrenal Gland Adrenal Gland: sits atop the kidneys
Adrenal Medulla: inner portion of gland, under nervous control, hypothalamus initiates nerve impulses that travel by way of the brain stem, spinal cord, and sympathetic nerve fibers to the adrenal medulla, which then secretes its hormones
Adrenal Cortex: outer portion of gland, under control of ACTH
Adrenocorticotropic Hormone (ACTH): stimulates adrenal cortex to produce its hormones
These portions have no physiological connection with one another
Stress of all types, including emotional and physical trauma, prompts the hypothalamus to stimulate the adrenal glands
Epinepghrine (Adrenaline) and Nonrepinephrine (Nonadrenaline): produced by the adrenal medulla and rapidly bring about all the body changes that occur when an individual reacts to an emergency situation
The release of epinephrine and nonrepinephrine achieves the same results as sympathetic stimulation – the "fight-or-flight" responses: increased the heart rate, rapid respiration, dilation of the pupils, etc.

13. Adrenal Cortex Adrenal Cortex Hormones:
provide a long-term response to stress
secretes small amounts of both male and female sex hormones
promote skeletal growth in adolescents
male hormones from the adrenal gland stimulate the growth of axillary and pubic hair at puberty
help sustain sex drive, or libido, in both men and women
2 major types:
Mineralocorticoids
Glucocorticoids
Mineralocorticoids: regulate salt and water balance, leading to increases in blood volume and blood pressure
Aldosterone is the most important
It also primarily targets the kidney where it promotes renal absorption of sodium and water, and renal excretion of potassium
Secretion of mineralocorticoids from the adrenal cortex is influenced by ACTH (adrenocorticotrpic hormone of corticotropin) from the pituitary gland

14. Adrenal Cortex Cont.
Glucocorticoids: regulate carbohydrate, protein, and fat metabolism, leading to an increase in blood glucose level
Cortisol: produced by the adrenal cortex, counteracts inflammatory response that leads to pain and swelling of joints in arthritis and bursitis
Cortisone: medication often administered for inflammation of joints, and other glucocorticoids can relieve swelling and pain from inflammation
Addison Disease: level of adrenal cortex hormone is low due to hyposecretion
Cushing's Syndrome: level of adrenal cortex hormone is high due to hypersecretion

15. Pancreas
Pancreas: long organ that lies transversely in the abdomen between the kidneys and near the duodenum of the small intestine
Composed of two types of tissue:
Exocrine
Endocrine
Endocrine Tissue: pancreatic islets, produces and secretes the hormones insulin and glucagon directly into the blood
Exocrine Tissue: produces and secretes digestive juices that go by way of ducts to the small intestine
Insulin and Glucagon: antagonistic hormones, both produced by the pancreas, help maintain the normal level of glucose in the blood
Insulin: secreted when the blood glucose level is high, stimulates the uptake of glucose by most body cells, not necessary for the transport of glucose into brain or red blood cells, but muscle cells and adipose tissue cells require insulin for glucose transport
Glucagon: secreted from the pancreas, when the blood glucose level is low; the major target tissues of glucagon are the liver and adipose tissue, stimulates the liver to break down glycogen to glucose and to use fat and protein in preference to glucose as energy sources

16. Pancreas Cont.
Diabetes Mellitus: fairly common hormonal disease in which insulin- sensitive body cells are unable to take up and/or metabolize glucose
Hyperglycemia: the blood glucose level is elevated; symptoms include perspiration, pale skin, shallow breathing, and anxiety
Polyphagia: person becomes extremely hungry
Insulin-dependent Diabetes Mellitus (IDDM), Type 1: pancreas does not produce insulin, condition is believed to be brought on by exposure to an environmental agent, causes immune cells to destroy the pancreatic islets
Hypoglycemia: either an overdose of insulin or missing a meal can bring on the symptoms of hypoglycemia (low blood sugar), symptoms include perspiration, pale skin, shallow breathing, and anxiety
Noninsulin-dependent Diabetes Mellitus (NIIDM), Type 2: usually occurs in people of any age who tend to be obese, amount of insulin in the blood of these patients is normal or elevated but the insulin receptors on the cells do not respond

17. Other Endocrine Glands
There are several other glands in the Endocrine System that also produce hormones
Include:
Gonads (ovaries in females, testes in males)
Thymus Gland (lesser-known)
Pineal Gland (lesser-known)
Few tissues within organs produce hormones or growth factors
Gonadotropic Hormone: stimulate the gonads to produce gametes and sex hormones

18. Ovaries and Testes
Hypothalamus and the Pituitary Gland control hormonal secretions of these organs
Testes: located in scrotum
Produce androgens (like testosterone) which are the male sex hormones
Ovaries: located in pelvis cavity
Produce estrogen/progesterone which are the female sex hormones

19. Thymus and Pineal Glands
Thymus Gland: lies beneath sternum, most active/largest during childhood
Lymphocytes: white blood cells which originate in the bone marrow and are responsible for certain defenses against specific invaders
Thymus-derived Lymphocytes (T-lymphocytes): what lymphocytes are transformed into once they pass complete development in the thymus
Thymosins: hormones that epithelial cells secrete that line the lobules of the thymus
Pineal Gland: located in brain, produces hormone known as melatonin – primarily at night
Melatonin: involved in our daily sleep-wake cycle; also regulates sexual development

20. Growth Factors
Numerous types of organs and cells produce peptide growth factors (stimulate cell division and mitosis)
Granulocyte and Macrophage Colony-Stimulating Factor (GM-CSF): causes bone marrow stem cells to form granulocyte or macrophage cells which are forms of white blood cells/leukocytes
Platelet-Derived Growth Factor: released from platelets and form several other cell types; helps in wound healing
Epidermal Growth Factor and Nerve Growth Factor: important in wound healing
Tumor Angiogenesis Factor: stimulates creation of capillary networks, released by tumor cells

21. Homeostasis
The Endocrine Systems works together with the Nervous System in order to maintain homeostasis
The Endocrine System helps regulate:
digestion
fuel metabolism
blood pressure and volume
calcium balance
response to the external environment

24. Chemical Signals
Chemical Signals: molecules that affect behavior of cells that have receptor proteins to receive them
Prostaglandins: potent chemical signals produced within cells from arachidonate (which is a fatty acid)
Local messenger chemicals that individual body cells produce
Not distributed in blood, act closely to where they were produced – locally

26. Effects of Aging
Thyroid disorders/Diabetes: most significant endocrine problems that affect our health and function as we age
Grave’s Disease: autoimmune disease that targets thyroid, symptoms of cardiovascular disease/increased body temperature/fatigue
Hypothyroidism/Hyperthyroidism: both seen in the elderly
Hypothyroidism (Myxedema) can fail to be diagnosed since symptoms are confused with aging