Courtney Llinares & Brenda Yik
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Transcript of Courtney Llinares & Brenda Yik
COURTNEY LLINARES & BRENDA YIK
COURTNEY LLINARES & BRENDA YIK
Hormones and theEndocrine System
THE ENDOCRINE SYSTEM AND HORMONES
What are hormones? Molecules that are diffused throughout the body to communicate
various regulatory messages to specific target cells
What is the endocrine system? One of two major bodily communication systems (the other being
the nervous system)
TYPES OF CELLULAR COMMUNICATIONS
Intercellular communications: different ways signals are sent between animal cells
Types of intercellular communications are endocrine, paracrine, autocrine synaptic, and neuroendocrine sigaling
Extracellular communications: Pheromones
Intercellular communication by secreted molecules
Bloodvessel Response
Response
Response
Response
(a) Endocrine signaling
(b) Paracrine signaling
(c) Autocrine signaling
(d) Synaptic signaling
Neuron
Neurosecretorycell
(e) Neuroendocrine signaling
Bloodvessel
Synapse
Response
EARLY ENDOCRINE/HORMONAL SYSTEMSCNIDARIANS: HYDRA Endocrine system was not yet developed,
but evidence has shown neurohormones in effect
Contains neuropeptides that stimulate processes
EARLY HORMONES/ENDOCRINE SYSTEM ANNELIDS: NEREIS
Marine worm Long ventral nerve cord with a segmented
ganglion Produces the peptide hormone neredine, in
the ganglion (early brain)
EARLY HORMONES/ENDOCRINE SYSTEMARTHROPODS: BUTTERFLY
Has an endocrine system and hormones for molting, development, and more
A brain hormone stimulates release of ecdysone from the prothoracic glands
HORMONES/ENDOCRINE SYSTEM MAMMALS: HUMANS
Have fully developed endocrine system with a variety of functional hormones
The endocrine systems is made of eight functional glands:• Hypothalamus• Pituitary• Thyroid• Parathyroids• Thymus • Adrenals • Gonads
Major endocrine glands:
Adrenalglands
Hypothalamus
Pineal gland
Pituitary gland
Thyroid gland
Parathyroid glands
Pancreas
Kidney
Ovaries
Testes
Organs containingendocrine cells:
Thymus
Heart
Liver
Stomach
Kidney
Smallintestine
CHEMICAL CLASSES OF HORMONES Three classes of hormones: 1. Polypeptides
2. Steroids
3. Amines
Hormones vary in solubility in aqueous and lipid environments
Water soluble hormones: polypeptides and most amines Lipid soluble hormones: steroids
Hormones differ in form and solubility
Water-soluble Lipid-soluble
Steroid:Cortisol
Polypeptide:Insulin
Amine:Epinephrine
Amine:Thyroxine
0.8 nm
EFFECTS OF HORMONES
Many hormones cause more than one type of cellular response
• Example: Epinephrine triggers glycogen breakdown in the liver, increases blood flow to many skeletal muscles, and more simultaneously
• Signaling by local regulators: local regulators are molecules that send chemical signals in seconds unlike hormones, but have the same pathways as hormones
Ex: Growth factors, and nitric oxide
FEEDBACK REGULATION
In simple endocrine pathways cells responds directly to and internal or environmental stimulus by secreting certain hormones
These responses link back to deduce the initial stimulus (negative feedback) or enhance the initial stimulus (positive feedback)
Signal Transduction Pathway Example
Stimulus Low blood glucose
Pancreas alpha cells secretes glucagon Endocrine
cell
Bloodvessel
LiverTargetcells
ResponseGlycogen breakdown,glucose release into blood
Neg
ativ
e fe
edb
ack
–
ANTAGONISTIC HORMONES AND DIABETES
Insulin and glucagon are antagonistic hormones that help maintain homeostasis in blood glucose levels
Diabetes mellitus: disorder caused by insulin level or response abnormalities
Treatment involves insulin injections, lifestyle changes, or medication
COORDINATION OF ENDOCRINE AND NERVOUS SYSTEMS
Hypothalamus connects the nervous and endocrine systems
Pituitary gland receives signals from the hypothalamus for various hormone excretions
Endocrine glands in the human brain
Spinal cord
Posteriorpituitary
Cerebellum
Pinealgland
Anteriorpituitary
Hypothalamus
Pituitarygland
Hypothalamus = brain
Thalamus
Cerebrum
THYROID REGULATION
In thyroid regulation a hormone cascade pathway occurs where a hormone stimulates the release many other hormones
The last of the secreted hormones activates a nonendocrine target cell
A hormonecasadepathway
Cold
Pathway
Stimulus
Hypothalamus secretesthyrotropin-releasinghormone (TRH )
Neg
ativ
e fe
edb
ack
Example
Sensoryneuron
Neurosecretorycell
Bloodvessel
Anterior pituitary secretes thyroid-stimulatinghormone (TSHor thyrotropin )
Targetcells
Response
Body tissues
Increased cellularmetabolism
–
Thyroid gland secretes thyroid hormone (T3 and T4 )
–
Disorders of Thyroid Function Hypothyroidism occurs when there is low secretion
of thyroid hormones
-Treatment:
-Levothyroxine medication commonly used to replace lacking thyroid hormone
Disorders of Thyroid Function Continued In humans, hyperthyroidism is condition in
which thyroid gland produces excessive amount of thyroid hormone
Treatment:-Antithyroid medications-Radioactive iodine
TROPIC AND NONTROPIC HORMONES
Tropic hormones: regulate the function of other endocrine cells or glands
Examples:
-TSH (thyroid-stimulating hormones) regulate the thyroid gland
-Follicle-stimulation hormone
Growth hormones: stimulates growth through tropic and nontropic effects
PARATHYROID HORMONE AND VITAMIN D
Parathyroid glands release the parathyroid hormone (PTH)
• Maintains homeostatic control of blood calcium levels directly and indirectly
• PTH synthesizes Vitamin D in the kidneys which acts directly by activating the release of Ca² ⁺
• calcitonin is a hormone that inhibits bone absorption and enhances calcium release by the kidney
COORDINATION OF THE ENDOCRINE AND REPRODUCTIVE SYSTEM
Gonadal sex hormones: affect growth, development, reproductive cycles, and sexual behavior
-The gonads produce and secrete three major categories of steroid hormones
(androgens, estrogens, and progestins)
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