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The Endocrine System. By Evil Mr. Bleecker. Endocrine vs Nervous System. NERVOUS. ENDOCRINE. Uses chemical hormones released from glands into the blood. Uses impulses sent along axons and chemical neurotransmitters at synapses. - PowerPoint PPT Presentation
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Endocrine vs Nervous System
NERVOUSNERVOUS ENDOCRINEENDOCRINE• Uses impulses sent along axons and chemical neurotransmitters at synapses
• Uses chemical hormones released from glands into the blood
• Receptors are on post-synaptic membrane
• Receptors are on the plasma membranes of target cells or intercellular
• Signals are very fast (milliseconds)
• Signals are slower (seconds to days)
• Response is immediate but short-lived
• Response is delayed but more sustained
Characteristics of Hormones
Hormones: exert their effects some distance from where they
are produced
are active under very low (nanogram 10-9) concentrations in the blood
usually have a short half-life in the body - several seconds to 60 mins. They are degraded by enzymes in their target cells or in the kidney or liver.
Characteristics of Hormones
Hormones bring about their effects by altering cell activity. The precise response depends on the target cell type.
Typical cellular effects include: Altering membrane permeability Stimulating protein synthesis Activating enzymes Inducing cells to secrete materials Stimulating mitosis
Control of Hormone Release
Synthesis and release of most hormones are regulated by a Negative Feedback SystemNegative Feedback System. As hormone levels rise, they cause target organ effects which inhibit further hormone release.
Hormone - Target Cell Specificity
Hormones circulate to virtually all tissues but influence the activity of only certain tissue cells, known as its target cells.
The Hypothalamus Contros the Anterior Pituitary
Hypothalamus “tastes blood” for hormone levels. It sends orders to the anterior/posterior pituitary to regulate the release of hormones.
Hormonal control rather than by nerves
Hypothalamus neurons synthesize releasing and inhibiting hormones.
Hormones secreted regulate the secretions of the anterior pituitary
GLANDHORMONETARGET ORGAN
NORMAL EFFECTS OF HORMONE
EFFECTS OF HYPER- AND HYPOSECRETION
CONTROL OF RELEASE
pituitary gland
Pituitary gland is located in the diencephalon below the hypothalamus
Structurally and functionally divided into: Anterior lobe Posterior lobe
Anterior Pituitary – Master Gland
growth hormone - GH prolactin- PRL adrenocorticotropic
hormone - ACTH thyroid stimulating
hormone - TSH lutenizing hormone - LH follicle-stimulating
hormone - FSH
pituitary glandgrowth hormone
Direct effects are the result of GH binding its receptor on target cells.
Target cells then believe they should take in more nutrients and grow, then divide
GROWTH HORMONE DISORDERS
Gigantism (Acromegaly) refers to a condition characterized by extreme physical size and stature due to a hyper-secretion of growth hormone during infancy, childhood or adolescence
12 year-old with mother
GROWTH HORMONE DISORDER #2
Dwarfism results from a GH deficiency in childhood, leading to a maximum height of 4 feet typically with normal body proportions. If diagnosed before puberty, hormone replacement therapy can promote nearly normal growth.
Dwarfed brothers with researcher in India
THE THYROID GLAND
Thyroid gland is a large gland located in the neck, just below the larynx. Needs IODINE to work properly.
Thyroid follicle cells stimulated by the anterior pituitary gland hormone TSH = Thyroid-stimulating Hormone
Secretes THRYOXIN = adjusts metabolism for all body cells – ie. Burning more glucose
Hypothyroid in Infants
Cretinism: Hypothyroid from end of 1st
trimester to 6 months after birth. Severe mental retardation
Short disproportionately sized body with a thick neck and tongue
Hypothyroid in Adults
In adults, it is called Myxedema:
Accumulation of proteins and fluid in subcutaneous tissue.
Symptoms: Decreased metabolic rate. Weight gain. Decreased ability to adapt
to cold. Lethargy (= fatigue)
Hyperthyroid in Adults
Grave’s disease
Elevated metabolic rate (rapid heartbeat, sweating, nervousness) and bulging eyeballs (expophthalmia)
HORMONES OF CALCIUM BALANCE
Calcitonin - protein Produced by thyroid
Reduces blood serum calcium levels by stimulating calcium uptake in bone
Important only in childhood when bones are quickly growing
Parathyroid Glands – Calcium II
Parathyroid Hormone (PTH) Produced by parathyroid glands
Opposite effect to Calcitonin Increases blood calcium levels by enhancing absorption of calcium in the small intestine, bone and promoting Ca2+ reabsorption in the kidney
Adrenal Gland
Paired organs that cap the kidneys. Each gland consists of an outer cortex
and inner medulla.
Adrenal Cortex
Adrenal cortex Stimulated hormonally (ACTH = Adrenal
CorticoTropic Hormone)
Secretes corticosteroids1. Glucocorticoids – raises blood
glucose, increases protein breakdown. Another is cortisone = anti-inflammatory
2. Aldosterone (Mineralcorticosteroid) – sodium reabsorption in kidneys
3. Sex Hormones – stimulates sex organs, development of reproductive organs
Negative Feedback Loop
Low blood sodium sensed by kidneys enzyme Angiotensin secreted which turns on secretion of aldosterone by kidney
Increased H20 absorbed to raise pressure
GLUCOCORTICOIDS At high concentrations, cortisol has pronounced anti-
inflammatory and anti-immune effects including:
Depressing cartilage and bone formation
Inhibiting inflammation
GLUCOCORTICOIDS in Excess
Cushing’s disease = glucorticoid excess
Symptoms include hyperglycemia (high blood sugar), loss of muscle and bone protein, moon face, and a redistribution of fat to the abdomen and posterior neck (causing a “buffalo hump”)
Excess of aldosterone causes excessive Na reabsorption, flooding tissues with water = edema
GLUCOCORTICOIDS – Insufficiencies
Addison’s disease is the major hypo-secretory disorder of the adrenal cortex, usually involving of both glucocorticoids and mineralcorticoids. Victims lose weight, demonstrate hypoglycemia and reduced levels of sodium, and show an increase in skin pigmentation (bronzing)
JFK had Addison’s, which he kept from public knowledge
Synthesizes and secretesEpinepherine and some NorEpinepherine
Sympathetic Nervous System hormones made here!!!
Fight or Flight!!!
Adrenal Medulla
ANTIDIURETIC HORMONE Antidiuretic Hormone (ADH; vasopressin) The main
regulator of body’s water (osmotic)balance
ADH increases the reabsorption rate of water in kidney
Secretion is regulated in the hypothalamus by osmoreceptors, which sense water concentration
Pancreas
Islets of Langerhans secrete insulin into the bloodstream
Insulin tells cells to absorb sugar and store it
Huge storage in liver as GLYCOGEN and in muscles!!!
Homeostatis & Regulating Blood Sugar Levels
Negative feedback loops If blood sugar rises, insulin is secreted to bring
it down If blood sugar lowers, glucagon is secreted to
place sugar into the blood
INSULIN
Diabetes mellitus results from hypo-secretion of insulin or hypo-activity of insulin. When insulin is absent or deficient, blood sugar levels remain high after a meal because glucose is unable to enter most tissue cells.
DIABETES
Type I diabetes mellitis (insulin-dependent) afflicts 750, 000 Americans.
Autoimmune disease (the insulin secreting beta cells of the Islets of Langerhans are attacked by immune cells)
Insulin is not produced or secreted, requiring regular insulin
injections.
DIABETES
Type II diabetes mellitis (non-insulin-dependent) afflicts 7.5 million Americans
Insulin resistance - Insulin is usually produced but the receptors do not respond. Loss of receptors possible – can have all the insulin there, but can’t absorb it.
DIABETES & HEREDITY Heredity plays a role - an estimated 30% of
Americans carry a gene that predisposes them to Type II diabetes.
Lifestyle play a role - Type II diabetics are almost always obese and sedentary. Adipose tissue produces a hormone-like chemical that may prevent uptake of insulin
PINEAL GLAND
Secretes melatonin: Production stimulated by
the hypothalamus Sets daily = circadian
rhythms. Melatonin secretion
increases with darkness and peaks in middle of night.
MELATONIN
Melatonin secretion has been linked to seasonal affective disorder (SAD) in people living in northern latitudes like Alaska. Melatonin is elevated in the winter months, and it may lead to depression, long bouts of sleeping, and eating binges. Sun lamps with a full spectrum of light are helpful therapy for some people.
The Midnight Sun
Thymus Gland & Hormones of the Immune System
Secretes thymosins that aid in the maturity of lymphocytes inside the lobules of the thymus.
Hormones of Digestion & Sex
Digestion - gut hormones – ex Gastrin & fullness
Sex hormones . . . . 1. Testes
produce androgens (testosterone) Puberty - secondary sexual characteristics such as
Pubic hair, Muscular strength, Deepening of voice2. Ovaries
produce estrogens and progesterone. Puberty - secondary sexual characteristics such as
Pubic hair, Breast development, Widening of hips, onset of menstrual cycle
Homeostasis – the Balance
Hypothalamus produces ADH and thus regulates blood osmolarity (osmotic balance)
Endocrine system controls secretion of epinephrine and norepinephrine and thus controls fight or flight responses.
Controls blood calcium levels. Muscle contraction.
Insulin encourages uptake of glucose by cells and storage of glucose as glycogen in the liver and muscles.