hormones

• control reproduction

• metabolism- rate cells undergo cellular respiration

• growth

• sleep

• blood levels for various substances (glucose, calcium, etc.)

• H2O balance

• stress

exocrine

• releases chemicals through ducts into cavities or out of body

• tear glands

• sweat glands

• salivary glands

• pancreas (digestion)

endocrine

• releases chemicals directly into the bloodstream

  • pituitary glands

  • thyroid

  • pancreas

• messages- hormones- circulation system (within plasma)

• works slowly

• effects last longer

• target cells have receptors only for specific hormones

how hormones know where to go

hormone: chemical messenger

• secreted by endocrine glands

• secretions into circulatory system

• hormone levels are maintained by feedback mechanism

receptor molecules: proteins located on cell membrane

• hormones only get accepted by cells with corresponding receptors

types of hormones

steroid

• can cross cell membranes

  • lipids

  • hydrophobic

  • non polar

• 1 messenger system

non-steroid

• protein hormones

• peptide hormones

• cannot cross cell membranes

• 2 messenger system

endocrine glands

hypothalamus

• located in brain

• connected and controls the secretions of the pituitary gland

• receives and relays info from nervous system (major link)

• TRH (thyroid releasing hormone)

• neurosecretory cells

pituitary gland

• located in brain- growth and reproduction

• “master gland“ controls many endocrine glands

• 2 parts (anterior and posterior)

• surrounded by capillaries to secrete into blood

• posterior (extension of the hypothalamus)

  • front part

  • composed of nervous tissue

  • neurosecretory cells

    • tell to secrete

    • both nervous and endocrine system

  • secretes nine hormones

  • oxytocin and ADH (antidiuretic hormone)

  • ADH

    • absorbs more water

    • diuretic- pee more : caffeine, alcohol

  • oxytocin

    • causes contractions in the uterus→ for birth

  • posterior has nerves, transmits signals

• anterior

  • back part

  • no specialized cells

  • produces most hormones

  • releasing hormones- tells anterior to make more hormones

  • inhibiting hormones- stop secreting hormones

  • FLAT PEG

    • F: FSH

      • follicle-stimulating hormone

      • tells ovaries/testes to mature gametes

    • L: LH

      • luteinizing hormone

      • similar to FSH

    • A: ACTH

      • adrenocorticotropic hormone

      • regulates hormone cortisol

      • cortisol: cope with stress

      • T: TSH

        • thyroid-stimulating

        • metabolism

      • P: Prolactins

        • makes breast produce milk during pregnancy

      • E: Endorphins

        • happy or pain

        • emotions

      • G: Growth Hormone

        • make bone/muscle tissue

        • stimulates new cell growth

thyroid

• located in neck- metabolism

• produces thyroxine (contains iodine)

  • regulates metabolism

    • hyperthyroidism (high thyroxine) → high metabolism → weight loss, fatigue, can’t sleep (wired), high energy, “hot“

    • hypothyroidism (low thyroxine) → low metabolism → weight gain, tired, less energy, cold

• calcitonin

parathyroids

• regulates calcium levels in the blood

• PTH

glucocorticoids

• steroid

• cortisol

• suppresses immune function

• maintain blood glucose

• gluconeogenesis= fat→glucose

mineralocorticoids

• steroid

• increase in Na+ reabsorbtion

• aldosterone

• increases blood pressure and volume

ovaries

• female gonads

• secretes estrogen

  • produces secondary sex characteristics (breasts, hips)

• secretes progesterone

  • builds up and maintains uterine lining

• androgens

• FSH- (follicle stimulating hormone) secreted by pituitary to stimulate sex hormones

• LH- lutenizing hormone secreted by pituitary to stimulate sex hormones

testes

• nale gonads

• secretes testosterone

  • secondary sex characteristics (lower voice, hair)

• maturation of sperm

• FSH

• LH

adrenal glands

• above kidneys

• releases hormones that help the body prepare for and deal with stress

• epinephrine (adrenaline)

• norepinephrine

water-soluble hormones

• nonsteroid hormones are derived from amino acids

• can’t pass thru the phospholipid bilayer- can’t enter cells

• bind to extracellular receptors on the surface of the membrane

• finds receptor on the surface of the target cell and activates it

• sets off a series of relay proteins-cascade

• the cellular response is either in the cytoplasm or in the nucleus

• include all protein hormones, amino acid and polypeptide hormones:

  • receptor on the outside of the cell

  • ex. thyroxin, epinephrine, melatonin, calcitonin

lipid soluble hormones

• only produced by sex organs and adrenal gland

• steroid hormones are lipid soluble

• can diffuse thru the plasma membrane

• diffuses thru membrane

• binds to open receptor protein in the cytoplasm or nucleus

• hormone-receptor-complex

  • attaches to DNA- turns genes on or off

    • testosterone

    • estrogen

    • progesterone

    • corticoids

  • goes into the nucleus, binds to DNA, turns the gene on

antagonistic hormones

• calcitonin (thyroid

  • decreases blood calcium

  • Ca2+ stored in bones

  • increase secretion of Ca++ in nephron

  • decrease absorbtin in small intestine

  • tetany

• PTH (parathyroid)

  • increases blood calcium

feedback mechanism

• when the level of one substance influences the level of another substance or activity of another organ-maintaining homeostasis

negative feedback

• when a variable triggers a counteracting response (homeostasis). (like a thermostat)

• ex:

  • insulin is released by the pancreas when glucose levels are too high

  • glucagon release by the pancreas when glucose levels are too low

positive feedback

• no counteracting response

• intensification of a response

• ex:

  • during labor and birth, pressure of the baby against cervix, and tissues in the pelvic floor, stimulates oxytocin and contractions

  • buildup of more pressure releases more oxytocin- positive feedback

thyroid feedback

• thyroxine affects metabolism

• increase- cells more active

• decrease- decreases in metabolic activity

• doesn’t determine release on its own

• controlled by the hypothalamus and anterior pituitary gland

  • hypothalamus monitors levels

  • when thyroxine is too low

  • hypothalamus secretes TRH thyroid releasing hormone

  • stimulates anterior pituitary gland

  • TSH thyroid stimulating hormone

  • TSH stimulates the release of thyroxine by the thyroid gland

thyroid regulates development and metabolism

• thyroxine

  • T3- contains 3 atoms of iodine

  • T4- contains 4 atoms of iodine

• hyperthyroidism

  • weight loss

  • high blood pressure

  • overheat

  • over sweating

  • graves disease- fluid behind eyeballs

• hypothyroidism

  • weight gain

  • intolerance to cold

  • lethargy

  • insufficient iodine in childhood- poor mental development, slow skeletal growth

  • insufficient iodine during adulthood- goiter- swelling of thyroid due to overproduction of TSH

nervous

• messages/impulses neurons

• faster response

• effects last shorter

• Melatonin- helps with the timing of the circadian rhythm, it causes you to feel sleepy late at night.

• FSH- follicle stimulating hormone; produced by pituitary gland; helps control the menstrual cycle and production of eggs by the ovaries

• LH- luteinizing hormone; in males: stimulates testosterone; in females: stimulates ovulation

• ACTH- adrenocorticotropic hormone; controls production of cortisol (hormone)

• TSH- thyroid stimulating hormone; pituitary hormone that stimulates the thyroid gland to produce thyroxine

• Prolactin- for females: lactation during breastfeeding, arousal, drive, maternal behavior. for males: immune system regulation and sperm creation.

• GH- human growth hormone, builds bone and muscles as well as metabolism

• Thyroxine- regulates energy levels and metabolism, regulates body temp and produces proteins for every cell in the body,

• Calcitonin- lowers  calcium levels in the bones, and fractures of calcium in the blood,

• PTH- parathyroid hormone, raises calcium levels for the bones and the blood.

• Thymosin- development and function of the immune system, maturation of T-Cells.

• Insulin- a hormone that is produced by the pancreas; plays a key role in regulating blood sugar levels in the body; helps to move glucose from the bloodstream into cells, where it can be used for energy or stored for later use

• Glucagon- a hormone that raises blood sugar level

• Adrenaline- aka epinephrine; a hormone that prepares your body for a fight or flight response

• Norepinephrine- aka noradrenaline, is a hormone that helps your body respond to stress

• Corticoids- a group of hormones that are produced by the adrenal cortex; play a role in regulating metabolism, immune response, and stress response

• Aldosterone- a hormone that regulates salt and water balance in the body

• Testosterone- a hormone that is involved in the development of male sexual characteristics, as well as in maintaining muscle mass and bone density

• Estrogen- a hormone that is involved in the development of female sexual characteristics, as well as in regulating the menstrual cycle and supporting pregnancy

Progesterone- a hormone that is involved in regulating the menstrual cycle and preparing the body for pregnancy

1. What is the function of the endocrine system?

The endocrine system regulates all biological processes including the brain, nervous system, the growth and function of the reproductive system ,metabolism, and blood sugar.

2. What is a hormone?

Hormones are chemical messengers that send information to different organs, muscles, and other tissues all over the body.

3. How do hormones know which cell to affect?

Only cells that receive those hormones have the corresponding receptors.

4. What is a gland? What is the difference between an endocrine and an exocrine gland?

Glands are organs that make one or more substances such as hormones. Endocrine glands release substances directly into the bloodstream. Exocrine glands release substances into a duct or opening to the inside or outside of the body.

5. What are the two types of hormones and how do they work?

6. protein hormones: made from chains of amino acids, react with receptors on the surface of the cell, works fast

7. steroid hormones: made from lipids, react with receptor sites inside the cell, works slow

6. What is a feedback mechanism and how does this work to help the endocrine system function at maintaining homeostasis.

A feedback mechanism maintains the desired levels of hormones in the body for homeostasis. An increase or decrease in the levels of the hormones triggers the feedback mechanism so it will keep the hormones balanced within the body. The feedback can either have a positive or negative effect on the results and the mechanism accounts for that.