chapter 26: regulation part i - the endocrine system new aim: how do chemical signals coordinate...

Chapter 26: Regulation Part I - The Endocrine SystemNEW AIM: How do chemical signals coordinate body functions?

I. Exocrine vs. Endocrine glands

A. Exocrine- have ducts (tubes made of cells) that carry secretion products to an outside surface

Ex. Sweat (eccrine), sebaceous, mammary, digestive (pancreas, liver, gall bladder), etc…

Remember that the lining of your digestive tract, nephron tubules, etc… are external surfaces – you do not need to cross any cell layers to get there.

Chapter 26: Regulation Part I - The Endocrine SystemAIM: How do chemical signals coordinate body functions?

I. Exocrine vs. Endocrine glands

B. Endocrine- ductless, hormones secreted into blood- IMPORTANT: hormones circulate and influence ONLY cells with receptors for them (target cells) - >50 known hormones in vertebrates

Fig. 26.1

There are two main types of hormone secreting cells

1. Endocrine cells, which typically secrete their hormone in response to a chemical stimulus like a ligand or an environmental change like high glucose levels that triggers signal transduction.

2. Neurosecretory cells, which are neurons (wire-like cells that transmit electrical signals) that secrete hormones. These cells are typically activated by an electrical signal and use electrical signals to secrete their hormones. Most are found in the hypothalamus – the master endocrine organ


II. The Endocrine System

A. Endocrine glands

B. Chemical regulatory system of body

Nervous system = other regulatory system of body

Fig. 26.3

Ex. Regulates metabolic rate, growth, maturation, reproduction, blood glucose, blood calcium, etc…

Why do we need two regulatory systems?

Endocrine = slower and more prolonged (long-lasting) effect

Both systems work closely together (interdependent)



D. Amino acid based vs. steroid hormones

i. Amino acid based (3 types)

1. amine (modified amino acid) - ex. epinephrine

epinephrine

gastrin insulin

2. Peptide - ex. gastrin

3. protein hormones - ex. insulin




i. Amino acid based (3 types)

How do amino acid based hormones “talk” to cells?

Fig. 26.2

4. Bind and activate surface receptors

1. amine (modified amino acid)

2. Peptide

3. protein hormones

5. Result: Turn genes On/Off or activate/deactivate enzymes, etc…

(can’t cross PM)




ii. Steroid hormone

1. Lipids made from cholesterol

Ex. Testosterone and estrogen

testosterone estrogencholesterol




ii. Steroid hormone

1. Lipids made from cholesterol

Ex. Testosterone and estrogen

How do steroid hormones “talk” to cells?

Fig. 26.2

4. Turn genes ON/OFF ONLY

3. Receptor protein usually a transcription factor

2. Cytoplasmic receptor protein




Fig. 26.2




iii. Exception to the rule

a. Thyroxine (T4) and triiodothyronine (T3)

triiodothyronine (T3)

- amine hormones- produced by thyroid- relatively non-polar, behave like steroids



E. Endocrine glands of vertebrates

i. Some have ONLY endocrine function

Ex. Thyroid and pituitary

ii. Some also have a non-endocrine function

Fig. 26.3

Ex. pancreas

Exocrine = digestive enzymesEndocrine = insulin release



E. Major vertebrate endocrine glands and their hormones

Pg. 521



E. Major vertebrate endocrine glands and their hormones

i. Steroid hormones made only by sex organs (testes and ovaries) and adrenal glands (specifically the adrenal cortex)



F. The hypothalamusi. Part of brain

iii. Connects nervous system to endocrine system

- receives info from nerves about internal and external environmentiv. Closely tied to pituitary gland – in fact, the posterior pituitary is made of cells that extend from the hypothalamus

ii. Master control center of endocrine system

Fig. 26.4



F. The Pituitaryi. Two parts

- composed of nervous tissue (extension of hypothalamus)1. Posterior lobe (posterior pituitary)

Fig. 26.4

- stores and secretes hormones made in hypothalamus

- Made of neurosecretory cells




2. Anterior lobe (anterior pituitary)

Fig. 26.4

a. composed of NON-nervous glandular tissue (endocrine cells)b. synthesizes own hormones, most control other endocrine glandsc. hormone release controlled by…Hypothalamus hormones




a. composed of NON-nervous glandular tissue2. Anterior lobe (anterior pituitary)

b. synthesizes own hormones, most control other endocrine glandsc. hormone release controlled by…Hypothalamus hormones

- Hypothalamus hormones that control AP

1. Releasing hormones

2. Inhibiting hormones

- Bunch of different hormones that signal AP to release a certain hormone

- Bunch of different hormones that signal AP to stop releasing a certain hormone



G. Example you need to know: Hypothalamus and AP interaction (Example)

2. Hypothalmus secretes TRH into blood1. cold external temperature

TRH = TSH releasing hormone

3. TRH stimulates AP to secrete TSH (thyroid stimulating hormone) into blood

Hypothalamus hormones

4. TSH stimulates thyroid to secrete the hormone thyroxine (T4) into the blood

5. Thyroxine (T4) binds to thyroxine receptors, which are found on most cells instructing them to increases metabolic rate of body cells – heat generated

NEGATIVE FEEDBACK

Fig. 26.4

(hypothalamus regulates body temp through thyroid)

6. Thyroxine (T4) and TSH inhibit hypothalamus from secreting TRH



G. Example you need to know: Hypothalamus and AP interaction (Example)

1. cold external temperature

TRH = TSH releasing hormone

3. TRH stimulates AP to secrete TSH (thyroid stimulating hormone) into blood

4. TSH stimulates thyroid to secrete the hormone thyroxine (T4) into the blood

5. Thyroxine (T4) binds to thyroxine receptors, which are found on most cells instructing them to increases metabolic rate of body cells – heat generated

NEGATIVE FEEDBACK(hypothalamus regulates body temp through thyroid)

6. Thyroxine (T4) and TSH inhibit hypothalamus from secreting TRH

2. Hypothalmus secretes TRH into blood



H. The Hypothalamus and Posterior pituitary (PP)i. REMINDER: hormones made in hypothalamus and stored/released in PP

1. oxytocin- causes uterine muscles to contract during child birth – polypeptide hormone

- mammary glands to pump milk

2. ADH (antidiuretic hormone or vasopressin)- Target organs are kidneys - reabsorb water from collecting duct of nephrons

Fig. 26.5

- Polypeptide hormone, see excretory system

ii. Neurosecretory cells extend into PP where they secrete hormone into blood

It is typically administered intravenously immediately after child birth as well to keep the contractions going to make sure the placenta comes out / is delivered.

Target organs (the organs targeted by the hormone)


II. The Endocrine SystemI. The Hypothalamus and Anterior pituitary (AP)

- neurosecretory cells of hypothalamus secrete RH or IH (releasing hormone / inhibitory hormone)

1. Hormones from AP that control other endocrine glands:

TSH - thyroid stimulating hormone

Fig. 26.5

- blood carries RH/IH to AP to control hormone secretion – each hormone released by AP is contolled by a different RH/IH

ACTH - adrenocorticotropic hormoneFSH - follicle stimulating hormoneLH - luteinizing hormone

2. Other hormones

GH - growth hormonePRL - prolactin

Endorphins (endogenous morphine)

FLAGTEP




Fig. 26.5

2. Other hormones


Endorphins

FLAGTEP

Human Growth Hormone (hGH) is a protein. It targets many cells and stimulates growth of these cells as well as mitotic division. As you might have hypothesized, levels of GH in the blood fall off with age.




Fig. 26.5

2. Other hormones


Endorphins

FLAGTEP

Prolactin is a protein as well. It promotes lactation (production of milk) in females.




Fig. 26.5

2. Other hormones


Endorphins

FLAGTEP

Beta-endorphin: A 31 amino acid polypeptide. Endorphins are neurotransmitters, which means they talk to neurons and tell them to fire or not to fire. We will discuss this in detail with the nervous system. In general, endorphins are released during exercise, excitement, and pain and bring about feelings of well being and pain reduction similar to morphine (endo – form within, orphin – morphine = endorphine)


II. The Endocrine SystemJ. Thyroid

1. located just below larynx

Fig. 26.3

- Thyroxine T4

2. Hormones produced (amine)

- Triidodthyronine T3


Both contain iodine




Fig. 26.6A

- Thyroxine T4




Both contain iodineRemember the Goiter - lack of iodine in diet – causes thyroid to swell like a balloon as it tries to make T3 and T4 under excessive TSH stimulation.




Fig. 26.6

- Thyroxine T4



Goiter - lack of iodine in dietWhy a goiter forms




Fig. 26.6

- Thyroxine T4



Goiter - lack of iodine in dietWhy a goiter forms

Iodized salt




3. Target Cells

- virutally all tissues

Fig. 26.3

- Thyroxine T4

4. Actions

- Adulthood: Stimulate and maintain metabolism in adults, maintain BP, heart rate, muscle tone, digestion and reproductive functions



- childhood: bone and nerve cell development



5. Disorders

- overheating, excessive sweating, irritable, high BP, weight lose

Fig. 26.3

i. hyperthyroidism

- too much T3 or T4

- Grave’s disease- autoimmune disease

- antibodies made against TSH receptors on thyroid

- Antibodies bind to receptors and activate them in the absence of TSH = hyperthyroidism



5. Disorders


i. hyperthyroidism

- too much T3 or T4



antibodies

- Antibodies bind to receptors and activate them in the absence of TSH = hyperthyroidism



5. Disorders


i. hyperthyroidism

- too much T3 or T4



- activates receptors in absence of TSH = hyperthyroidism

antibodies

20-25% of people with Graves' disease will suffer from Graves' ophthalmopathy (a protrusion of one or both eyes), caused by inflammation of the eye muscles due to attacking autoantibodies.


II. The Endocrine SystemI. Thyroid

E. Disorders

ii. hypothyroidism

- weight gain, lethargy, intolerance to cold

- caused by defective gland or iodine deficiency (goiter)

beforeAfter hypothyroidism


II. The Endocrine SystemI. Thyroid

E. Disorders

ii. hypothyroidism

- weight gain, lethargy, intolerance to cold

- caused by defective gland or iodine deficiency (goiter)

cretinism

- Cretinism if occurring in childhood

a. retarded skeletal growth and poor mental development


II. The Endocrine System2. Blood calcium homeostasis (10mg/100ml)

A. Some uses of calcium

i. Help neurons to transmit signals

ii. Muscle contraction

iii. Blood clotting (coagulation)

iv. Cotransport across PM

Cotransport occurs when a cell uses energy to actively pump a substance like Ca++ or H+ across a membrane resulting in an electrochemical gradient similar to the pumping of H+ into the intermembrane space of the mitochondria or into the thylakoid disk. When the substance diffuses back passively, the energy is used to transport another molecule with it from low to high concentration (active) – therefore your link facilitated diffusion with active transport.



C. Hormones involved

i. Calcitonin

B. NOT UNDER HYPOTHALAMUS/PITUITARY CONTROL

2. Blood calcium homeostasis (10mg/100ml in blood normally)

Fig. 26.3

- secreted by thyroid

- lower blood Ca++

It is a polypeptide:




i. Calcitonin (calcium in)


2. Blood calcium homeostasis (10mg/100ml)

Fig. 26.3


- lowers blood Ca++

ii. Parathyroid hormone (PTH)

- secreted by parathyroid glands

- raises blood Ca++

PTH (protein)




i. Calcitonin



Fig. 26.3


- lower blood Ca++


- secreted by parathyroid

- raises blood Ca++

**These are antagonistic hormones(opposite effects)




i. Calcitonin




- lower blood Ca++


- secreted by parathyroid

- raises blood Ca++


four embedded in thyroid



D. Mechanism of action


Fig. 26.7

four embedded in thyroid

i. Calcitonin targets:

- bone, kidneys

ii. PTH targets:

- intestines, bone, kidneys

IMPORTANT: What you need to realize is that the levels are ALWAYS fluctuating up and down like a sinusoidal wave. This is a hallmark of feedback. It never stays at 10mg/100ml and this goes for the concentration of anything in your body like protein levels in a cell or blood glucose…. Nothing is static, everything is dynamic.



Fig. 26.7



E. Vitamin D

i. sources

- food: cheese, butter, margarine, milk, fish, cereal, etc…

- skin makes it when exposed to sun

ii. Activated in liver and kidney to become a hormone (see figure)

iii. Kidney secretes activated form (Calcitriol)

- works with PTH

- targets bone and intestines similar to PTH

Vitamin D



B. Pancreas

i. Endocrine and exocrine gland

A. NOT UNDER HYPOTHALAMUS/PITUITARY CONTROL

3. Blood glucose regulation (90mg/100ml)

Fig. 26.3



B. Pancreas

i. Endocrine and exocrine gland

ii Islets of Langerhan

- endocrine portion

A. NOT UNDER HYPOTHALAMUS/PITUITARY CONTROL


- made of alpha (α) and beta (β) cells



i. insulin

- produced by beta cells

ii. glucagon

- produced by alpha cells



- raises blood glucose

- lowers blood glucose


insulin

glucagon

- Glucose is gone (glucagon…get it?)



i. Insulin targets:

- liver, body cells (fat cells, muscle cells)

ii. Glucagon targets:

- liver



Fig. 26.8

Hyperglycemia vs. Hypoglycemia



STORY:You eat a candy bar or anything with carbs and your blood sugar raises above 90mg/100ml. Proteins on the surface of pancreatic beta cells located in the Islets of Langerhan signal the beta cells to secrete insulin (take glucose in) into the blood. Insulin circulates and binds to insulin receptors on hepatic (liver) cell, adipocytes (fat cells), and myocytes (muscle cells). Signal transduction occurs and the cells send glucose transporter proteins to their membranes. Glucose enters by facilitated diffusion and is converted to glycogen in liver and muscle, and to triglycerides in adipocytes. The blood sugar levels drop causing the beta cells to stop secreting insulin.



Fig. 26.8



STORY:When they fall too low, the proteins on the surface of pancreatic alpha cells also located within the Islets of Langerhan send a signal into the alpha cells causing them to secrete glucagon (glucose is gone) into the blood. Glucagon will circulate and bind to glucagon receptors located on hepatocytes and adipocytes causing them to breakdown glycogen and release glucose. Why would you not signal the myocytes to release glucose? Because the muscles always need the glucose to make ATP so they can contract. Muscles do not store it for the body, they store it for themselves. The blood sugar levels rise causing the alpha cells to stop secreting glucagon.



Fig. 26.8



i. Diabetes mellitus

a. body cells do not absorb glucose (blood glucose high)

d. Two types

E. disorders


1. Type I insulin dependent (early onset)

b. affects 5 out of 100 in US

c. 350,000 die from disease/year

- autoimmune disease against beta cells

- develops before age 15 typically

- don’t produce enough insulin

- insulin injection required

- genetically engineered (human insulin gene put into a plasmid and inserted into bacteria)

Insulin pump attached to user





d. Two types

E. disorders


1. Type II NON-insulin dependent (late or adult onset)



- faulty/missing insulin receptors on cells

- 90% of US cases are Type II

- Insulin is being made just not being “seen”

- typically develops after 40

- control sugar intake (diet)

- drugs that reduce glucose levels

- Treatment





d. Two types

E. disorders


1. Type II NON-insulin dependent (late or adult onset)



i. Cause

- Genetic predisposition combined with environmental triggers like obesity, hypertension, elevated cholesterol, high fat diets and inactive lifestyle.

- Managed by exercise and diet management

ii. Treatment




a. body cells do not absorb glucose (hyperglycemia = blood glucose high)

d. Type I and Type II

E. disorders


Fig. 26.8

e. Result



- Cells don’t take up glucose resulting in high blood glucose levels, burn fat/proteins instead

- Glucose seen in urine because kidneys can’t take it out of the proximal tubule quick enough

- High glucose levels cause




E. disorders


Fig. 26.9



ii. Hypoglycemia (low blood glucose level)

a. Beta cells secrete too much insulin

E. disorders


b. Diabetic takes too much insulin

c. Tumors that secrete insulin

d. Prolonged starvation

Treated by -1. Increase meals with easily digestible carbs. -2. More extreme cases can be treated with medications like glucocoritcoids (steroid hormones secreted by the adrenal cortex that cause a rise in blood glucose) or -3. part of the pancreas may need to be surgically removed to reduce insulin secretion.



i. On top of each kidney – kidney hat

ii. Secrete hormones involved in the organisms response to physical and/or emotional stress

A. Adrenal glands (two)

4. Mobilizing response to stress

iii. Two glands in one

Fig. 26.3

Fig. 26.10



i. On top of each kidney

ii. Secrete hormones involved in stress



iii. Two glands in one Fig. 26.101. Adrenal medulla

- central portion








Fig. 26.10

1. Adrenal medulla

- central portion- produces/secretes fight-or-flight hormones

a. Epinephrine (adrenaline)

b. Norepinephrine (noradrenaline)

- short/term response, subsides rapidly

- responds to nerve signals (must be rapid if you are in danger)





Fig. 26.10








Fig. 26.10

1. Adrenal medulla

2. Adrenal cortex

- outer portion- slower, long lasting stress response- responds to endocrine signals (ACTH from AP)- Hormones released = corticosteroids (two types)

a. Mineralcorticoidsb. glucocorticoids

i. Cortisone (hydrocortisone) - suppresses inflammation, typically given as an injection to an inflamed region like a major joint (elbow or knee)

Chapter 3 - The Molecules of Cells

AIM: Describe the structure/function of lipids. Corticosteroids

1. Glucocorticoids

a) Glucose Cortex Steroid

b)Regulate carbohydrate, fat and protein metabolismc) Anti-inflammatory affect – reverse immune system activity after infection is goned) ex. Cortisol and cortisone (cortisone shots)

Chapter 3 - The Molecules of Cells

AIM: Describe the structure/function of lipids. Corticosteroids

2. Mineralcorticoids

a) ex. Aldosterone

b) Helps to control salt (like sodium, which is a mineral – ions required by biological systems) and water levels in the bodyc) Mineral cortex steroid





Fig. 26.10



A. gonads

5. Sex hormones

Fig. 27.2

i. sex glands- ovaries and testes- secrete hormones in addition to gamete production

Fig. 27.3



A. gonads

4. Sex hormones


ii. Sex hormones (3 categories) - all present in males AND females at different levels.

1. Estrogensa. High in females compared to androgens

b. Maintain female reproductive system

c. Promote development of female secondary sex characteristics:

- smaller body size, higher pitch voice, breasts, wider hips



A. gonads

4. Sex hormones



2. progestinsa. ex) progesterone

b. Prepare uterus to support the embryo



A. gonads

4. Sex hormones



3. androgens

- testosterone is the main one

a. High in males compared to estrogens

b. Development and maintenance of male reproductive system

c. Promote development of male secondary sex characteristics:

- low-pitched voice, facial hair, large skeletal muscles



A. gonads

4. Sex hormones



- estrogens, progestins, androgens

- FSH and LH

iii. Regulated by hypothalamus and AP

Fig. 26.5

FLAGTEP


II. The Endocrine System4. Sex hormones

B.Steroid Biosynthesis (just for fun)

chapter 26: regulation part i - the endocrine system new aim: how do chemical signals coordinate...

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