hormonal control

What’s the difference between the nervous and hormonal system?

What are hormones and the main types of hormones?

Hormones - chemical messengers secreted directly into blood stream,

Main types

1. Amino acid derravitives eg melatonin

2. Peptide hormones eg oxytocin

3. Steroid or lipid derravitives - can pass through membranes eg oestrogen

What do non steroid hormones bind to?

Receptors found on the cell surface

What are examples of peptide and steroid hormones?

What are the first messengers and second messengers?

First messengers - hormone that brings info or signal from endocrine

Second messengers - non steroid hormones don’t enter the cell they bind to receptors on cell surface membrane

What are non steroid hormones and their functions?

• hydrophilic - cannot pass through membranes

• Bind to receptors on cell surface membranes

• Triggers cascade reaction medicated by second messengers eg glucagon - phosphorylation breaks into glycogen

What are steroid hormones and there functions?

Lipid soluble

Pass thru lipid component of cell membrane and bind to receptors

Form hormone receptor complexes which acts as a transcription factor which in turn facilitates or inhibits transcription of a particular gene eg progesterone

What two parts are adrenal glands made up of?

1. Adrenal cortex - outer region of the gland that produces hormones eg cortisol and aldosterone - steroid hormones

2. Adrenal medulla - inner region that produces non essential hormones eg adrenaline

What 3 main types of hormones is the adrenal cortex controlled by?

1. Glucocorticoids and Corticosterone

2. Mineralcorticoids

3. Androgens

What do glucocorticoids and corticosterone do?

1. Glucocorticoids - cortisol = regulate metabolism by controlling how body converts fats and proteins and carbs to energy - regulates blood pressure and response to stress. - cortisol

2. Corticosterone = works with cortisol to regulate immune system and surpress inflammatory actions

What do mineralcorticoids do?

1. Mineralcorticoids - aldosterone - controlling BP by balancing salt and water concentrations - release medicated by signals triggered by kidneys

Eg aldosterone

What do androgens do?

1. Androgens - small amounts of make and female sex hormones are realsed, plays a bigger role after menopause

What’s adrenalines role in the adrenal medulla?

Adrenaline - increases heart rate blood glucose and breathing rates

What’s noradrenalines role in the adrenal medulla?

Noradrenaline - works with adrenaline to increase heart rate widen pupils and widen lung passages

Pancreas - what do the exocrine glands do?

Produce enzymes and release them via a duct into the duodenum

What enzymes are released from the acinar cells?

1. Amylases

2. Proteases

3. Lipases

What do acinar cells do?

Produce and release enzymes

What enzymes are released from the acinar cells?

1. Amylases

2. Proteases

3. Lipases

Where are islets of langerhans found and what are they responsible for?

Within the exocrine tissue

They are responsible for producing insulin and glucagon

What cells are within the islets of langerhans?

Alpha and beta cells

What do alpha cells do?

Alpha cells - produce and secrete glucagon, larger and more numerous

What do beta cells do?

Produce and secrete insulin

What does glyconeogenesis mean?

Formation of new glucose

What is glycogenolysis?

Glycogen is broken down into glucose

What is glycogenesis?

Production of glycogen

What is hypoglycaemia?

LOW GLUCOSE LEVELS

What is hyperglycaemia?

HIGH GLUCOSE LEVELS

What increases blood glucose?

1. Diet

2. Glycogenolysis

3. Gluconeogenesis

What can decrease blood glucose?

1. Respiration

2. Glycogenesis

Give an example of negative feedback?

1. Insulin - too high

2. Glucagon - too low

What is insulin produced by?

Beta cells of the islets of langerhans

What are the 5 things insulin does?

1. Increases rate of glucose by absorption by cells

2. Increases rate of glycogenesis

3. Increases rate of glucose to fat conversion

4. Increases respiratory rate of cells

5. Inhibits the release of glucagon from the alpha cells of the islets of langerhans

What is insulin broken down by and what is the result of that?

• broken down by enzymes in liver cells

• As a result insulin has to be constantly secreted and fluctuates depending on the food eaten

What happens when glucose falls below a set level and what is that an example of?

Beta cells reduce their secretion

This is an example of negative feedback

What is glucagon produced by?

Alpha cells

What happens when glucose - too low?

Cells detect the fall and respond by secreting glucagon directly into blood stream

Which cells have glucagon receptors?

Liver and fat cells

What is the process of insulin secretion in beta cells?

1. Membrane of b cells = open potassium channels + closed calcium channels

2. Normal BG = K+ channels = open and diffuses out of cell - inside cell - 70mv

3. Blood glucose = rise glucose enters via glucose transporter

4. Glucose metabolised in mitochondria = ATP created

5. ATP binds to K+ channels and closes them

6. K+ ions can’t diffuse out + P.D rises to -30mv so depolarisation occurs

7. Depolarisation causes voltage gated calcium channels to open

8. Calcium ions enter cell and cause secretory vesicles to realease insulin by exocytosis

What is the process of the insulin response pathway?

1. Insulin binds to target cell

2. Activates enzyme tyrosine kinase

3. Causes phosphorylation of inactive enzymes in cell

4. = converts glucose to glycogen + fats are used up in respiration

5. Extra glucose can now move into cell out of blood stream

What is the process of glucagon release?

1. Hypoglycaemia = trigger - when blood sugar = low= less glucose entering alpha cells

2. So cellular energy changes - reduced glucose intakes leads to decrease in ATP within alpha cells

3. Low ATP = some potassium channels to close = prevents potassium from leaving the cell - buildup of positive charge inside the cell

4. Positive charge opens voltage gated calcium channels - ca2+ rushes into cell

5. Influx of calcium triggers glucagon filled vesicles to fuse with cell membrane and release glucagon into blood stream via exocytosis

What is the glucagon response pathway?

1. Glucagon binds to receptor on hepatocytes

2. Stimulating G protein inside membrane

3. Activating adenylyl cyclase inside cell

4. This converts ATP - cAMP

5. Which triggers series of enzyme controlled reactions

What happens after glucagons response?

1. Glycogenolysis - liver breaks down glycogen into glucose

More fatty acids used in respiration

Increasing gluconeogenesis - increasing conversion of amino acids and glycerol in liver

What are the common symptoms of diabetes?

• high blood glucose

• Glucose in use in

• Excessive need to urinate

• Excessive thirst

• Constant hunger

• Weight loss

• Blurred vision

• Tiredness

What is type 1 diabetes?

• unable to produce insulin As beta cells don’t produce it

• Cause isn’t known

• Condition - autoimmune response - the immune system attacks the beta cells

What is type 2 diabetes?

• cannot effectively use insulin

• Beta or body cells dont respond to insulin as glycoprotein receptor on cell membrane doesnt work

What is the treatment for type 1 diabetes?

• insulin injections - increase blood glucose absorbed by cells and causes glycogenesis - lowers blood glucose levels

• test blood Glucose by pricking finger

What is the problem with insulin injections?

• too little insulin injected they may experience hypoglycaemia - low BG so unconsciousness may occur

• Too much - hyperglycaemia - high BG

What are the treatments for type 2?

• regulate carb intake through diet and excersise

• Lose weight

• Drugs to stimulate insulin production

How did insulin use to be obtained to put in our bodies?

1. Use to be obtained from pancreas of cows and pigs - difficult and expensive

How is insulin now obtained and why is it better?

• 1955 structure of human insulin was identified and now made by genetically modified bacteria

• Human insulin better :

• Pure form and less likely to have allergic reactions

• Higher quantities can be produced

• Production costs are cheaper

• Religious or ethical issues are overcome

What are ways that have been tested to treat diabetes?

1. Pancreatic transplants - after 1 year 80% =0.0253 years no symptoms

2. Injected with pancreatic cells - less then 8% successful

What is the stem cells treatment used to treat diabetes?

1. Totipotent stem cells have potential to grow into any cells

2. Research focused on converting them into beta cells either once in patient or in the lab

3. Requires embryonic stem cells

4. Alternative - using umbilical cord stem cells

What are the advantages of stem cells treatment used treatment?

• donor availability not an issue - unlimited amount of cells can be produced

• Reduces likelihood of rejection

• No need for insulin injections

What is a disadvantage of stem cells treatment?

• controlling growth and differentiation of stem cells is limited - may cause growth of tumor

What are three target cells of adrenaline?

• smooth muscle

• Cardiac muscle

• Hepatocyte