A&Pll: Chap. 25 & 26 The Endocrine System

*Everything highlighted in yellow is part of quiz review. Know the features of hormones and what they do for quiz #1

The Endocrine System

• Control system of the human body. 

• Produces chemical messages in the form of HORMONES

• Made up of specialized glands that secrete hormones into the bloodstream. 

Nervous System vs. Endocrine System

Differences:

• hormones can stimulate more blood cells than neurotransmitters

• however, the nervous system functions a lot faster (electrical impulses)

Similarities:

• Both endocrine + nervous systems exhibit control via a feedback system

Hormones

• Chemical messages that are released from glands

• Only act on a target tissue or organ with specific receptors for specific hormone.

• ALL hormones have ONE common feature – all travel through bloodstream *Ductless System

Chemical Classification of Hormones 

1. Non Steroidal (proteins) Amino Acid based - usually long chains

   • organic compounds that make protein

   • nitrogen, oxygen, carbon+hydrogen

   • synthesize from tryptophan and tyrosine

2. Steroids – derived from Cholesterol

   • Lipid soluble, easily passes through the plasma membrane

   • Works for the effective functioning of the body

   • Ex. testestoraone, aldosterone, cortisol

Hormones Stimulus - Cellular

• Change permeability or potential of plasma membrane by opening ion channels

• Synthesis of protein including enzymes within cell

• Activates inactive enzymes or inhibits active enzymes

• Induces secretion by cells

• Stimulates mitosis

Dual Functioning Endocrine Glands

Hypothalamus

• Nerve cells in hypothalamus make chemicals that control release of hormones from pituitary gland

• gathers info sensed by brain (light, temp, feelings) to influence hormone release from pituitary

  Pancreas

• Part of Endocrine (insulin & glucagon) and digestive system (digestive enzyme)

  Gonads

•  Testes in males (Sperm) and  Ovaries (eggs) in females

Negative Feedback Loop

• Usual regulatory mechanism for hormone production in the endocrine System

• Causes a decrease in function

• Keeps concentration of hormones in a narrow range

Negative Feedback Loop - Stress

CRH = corticotropin releasing hormone

ACTH = adrenocorticotropic hormone

Adrenal Glands = fight or flight

Major Endocrine Glands in the body

• Hypothalamus - brain

• Thyroid - neck

• Pituitary - brain

• Pancreas - abdomen

• Parathyroid - neck

• Thymus - chest

• Adrenals - on top of kidneys

• Pineal - brain

• Reproductive glands - gonads

Endocrine Glands in the Body - Infundibulum

• stemlike stalk that connects the hypothalamus to the pituitary gland

Endocrine Glands in the Body - Hypothalamus

• Connects endocrine system with nervous system

• Main function to tell pituitary gland to start/stop making hormones

• Nerve cells make chemicals that control release of hormones from pituitary

• Gathers sensory information from sensed by the brain, then sent to pituitary gland

Endocrine Glands in the Body: Thyroid Gland

Located in the anterior neck, the surface of the trachea

• Hormone: 

  • Thyroid Hormone (T3-T4)

    • Stimulated by thyroid Stimulating hormone (TSH) from Anterior Pituitary

  Calcitonin Function: 

• Elevates metabolic rate

• increases  heart rate and respiration rate

• stimulates appetite

• Reduce blood Ca+

Thyroid Gland

• Hormone: calcitonin

• Function: 

  • Acts to reduce blood Calcium levels

  • Inhibits the activity of osteoclast (bone breakdown)

Thyroid Gland Diseases

Hypothyroidism - decrease in T3/T4

Hyperthyroidism - increase in T3/T4

Thyroid Gland - Autoimmune Disease

Graves Disease (hyperthyroidism)

•  - Characterized by: unexplained    

•    weight loss, nervousness,

•    increased heart rate, and the 

•    protrusion of the eye

• Hashimoto Disease

•   (hypothyroidism)

•  - Characterized by: large goiter,

•    primarily affects middle-aged

•    women, fatigue, puffy face,

•    hoarse voice, depression, pain in

•    joints 

Pituitary Gland – Master Gland

ANTERIOR LOBE:

Glandular part

Secrets hormones for 6 targets

HORMONES

• Growth hormone (GH)

• follicle-stimulating (FSH)

• luteinizing hormone (LH)

• adrenocorticotropic

• hormone (ACTH)

• thyroid-stimulating hormone (TSH)

• Prolactin (PRL) – non tropic

POSTERIOR LOBE:

• Neural part

• Secrets 2 hormones

• Signal from Hypothalamus

• Hormones

 - Oxytocin

 - Antidiuretic (ADH)

Anterior Pituitary: HGH

Hormone:  Human Growth Hormone(hGH)

• Function: 

  • Peptide hormone stim growth

  • speeds up the breakdown of fat (lipids)*

  • shifts cell’s use of nutrients away from carbohydrates (glucose) and towards lipids as an energy source*

  • GH and insulin function as antagonists*

  • Cell reproduction/regeneration

  • Regulates body composition, body fluids

  • Mental function

  • Bone & muscle growth

  Diseases: 

  • Acromegaly

  • Gigantism

  • Pituitary Dwarfism

quiz question: are GH and insulin synergists? FALSE

Anterior Pituitary: ACHT

Hormone: adrenocorticotropic hormone (ACTH)

• Function: 

  • Maintains the growth and development of the adrenal gland

  • Regulates levels of Cortisol

  • ACTH Secreted by pituitary gland

• ACTH Stimulates Adrenal Cortex 

  Diseases:

  Cushing’s Disease

  Characterized by: upper body obesity, rounded face, increased fat around the neck, and relatively slender arms and legs.

Anterior Pituitary: TSH

Hormone: thyroid stimulating

  hormone (TSH)

Function: 

•  - stimulates production of  

•    Thyroxin(T4) and  

•    Triiodothyronine (T3) by Thyroid gland

•  * T4 must be converted to T3 for body to use 

(Liver main area – Selenium required to remove molecule of Iodine

Anterior Pituitary: PRL

Hormone:

prolactin (PRL)

Function:

Stimulates the mammary glands to secrete milk for lactation

Anterior Pituitary

Hormone: follicle stimulating hormone (FSH)

• Function: 

  • Females: initiates development of oocytes (stimulates growth of ovarian follicles)

  • Males: initiates development of sperm

  Hormone: luteinizing hormone (LH)

  Function: 

  • Females: stimulates secretion of estrogen/progesterone

  • Males: stimulates secretion of testosterone

Anterior Pituitary Hormones

F: FSH

L: LH

A: ACTH

T: TSH

P: Prolactin

I: Ignore

G: Growth Hormone

Posterior Pituitary Gland: Two Hormones

Two Hormones made by axons of the Hypothalamus (Neural)

1. Oxytocin

• stimulates uterine contraction, birth hormone (increases contraction)

• men also secrete it

  2. Antidiuretic (ADH) = vasopressin, stimulates kidneys to absorb water

• prevents the formation of a large volume of water and conserves water

• Diabetes Insipidus – hyposecretion 

quiz question: birth hormone relates to which gland? Pituitary

Posterior Pituitary

• Hormone: Antidiuretic hormone (ADH) or vasopressin

  Produced in Hypothalamus

  Released by Post Pituitary

• Function: 

  It helps the Kidney manage the amount of water in the body

  If ADH levels are low – it increases Urine output

Pineal Gland

Hormone: melatonin

Function: 

• Body’s biological clock 

• Wake sleep cycle

• Sunlight goes down, and melatonin rises

Parathyroid Gland - On top of the Thyroid

Hormone: parathyroid hormone (PTH)

Function:

• Works with calcitonin to help control blood Ca+ levels (calcitonin: decreases reduces blood calcium levels while PTH increases blood calcium)

• Does the opposite of calcitonin*

Adrenal Gland

Located on top of each kidney

- Produce hormones you can not live without

- Mediate short- and long-term responses to stress

Two Parts:

1. Adrenal Cortex

• outer part

2. Adrenal Medulla

• inner part

Adrenal Gland: Adrenal Cortex

Hormones:

• Cortisol

• Aldosterone

• Adrenal androgens

Function:

Increases blood glucose levels, reduces inflammation, increases blood pressure, and increases the storage of (visceral) fat

Adrenal Cortex: Cortisol

• A Flight or Fight Hormone

• Steroid Hormone

• Controls body response to Stress

• Controls Salt and water balance

• Immune system

• Manages how body uses carbohydrate, fats and proteins

• Increases blood sugar level (glucose)

  Disease:

• Cushing Syndrome – too much (Hyper)

• Addison’s Disease – too little (Hypo)

Adrenal Cortex: Aldosterone

Steroid Hormone

• Essential for Sodium (Na+) conservation in kidney, salivary glands, sweat glands and colon

• Secretion of Potassium (K+)

• Increases blood volume

• Increases blood pressure

Hyperaldosterone – fluid retention, Increased BP, weaknness, cause loss of K+ and retention of Na+

Hypoaldosterone – Low Na+ (hyponatremia), High Pa+ (hyperkalemia), and too much acid (metabolic acidosis)

Conn’s Syndrome – very rare, too much (Hyper)

Adrenal Cortex: Androgen

• Steroid Hormone

• Play a role in male traits and reproductive activity

• Kick starts puberty

• Present in both males and females

Adrenal Medulla- core of Adrenal gland, inner part

Flight or Fight response & Extension of the Autonomic nervous system

Main Hormones

• Epinephrine- adrenaline (increases HR, dilate airways, dilates blood vessels, acts on histamine)

• Norepinephrine (alertness, BP regulation, mood regulation- SNRIs)

• Dopamine (pleasure, motor control, mood, attention, vasoconstriction)

Pancreas

• Maintains homeostasis of blood glucose levels 

• Releases directly into blood

• Dual Functioning

• Produces 2 antagonist Hormones 

  1. Insulin – lowers BS, moves glucose into cells

  2. Glucagon – increase BS

     (^ antagonists)

• Type I DM – shortage of Insulin; impaired insulin production

• Type II DM – lack of receptors in target cells'; impaired insulin secretion

  MOST COMMON ENDOCRINE DISORDER*

Heart

Hormone: atrial natriuretic peptide or hormone (ANP/ANH - promotes sodium loss)

Function:

• Targets Kidneys & Cardiovascular System

• Released from R Atrium

• blood volume/pressure

• causes salt to move from the blood to the kidney

• Increase urinary excretion

Gland: Testes

Hormone: testosterone

Function: Growth and maintenance of male sexual characteristics and for sperm production

Gland: Ovaries

Hormone: estrogen

Function: development and maintenance of female sexual characteristics

Hormone: progesterone

Function: maintenance of uterine lining for pregnancy

Sex hormones are produced by: the testes, ovaries, and adrenal glands (androgens)*

Gland: Placenta

Hormone: human chorionic gonadotropin (hCG)

Function: Stimulates development of fetus, and hormone secretion by maternal ovarian tissue for first trimester of pregnancy

Digestive Glands

Hormone: leptin

Gland: adipose tissue - plays a role in energy balance*

Function: Signal of how much fat is stored and Stimulates reduction of appetite

Hormone: ghrelin

Gland: stomach

Function: Stimulates hunger and is also linked to reward and pleasure in the brain

GI Tract

In the mucous lining of the _____, other cells secrete ___ hormones that play a regulatory role in ___ process

Ex. secretin

Antagonists: Calcitonin and Parathyroid Hormone

Calcitonin

• reduce blood calcium levels

• inhibits the activity of osteoclasts to break old bone

Parathyroid Hormone (PTH)

• increase blood calcium levels

• promotes the breakdown of old bone

quiz question: parathyroid can cause an increase in ossification: false