Epi/Nepi and other catecholamines stimulate BAR --> BAR linked to G(+) regulatory protein in the cell wall --> which activate the enzyme AC --> AC catalyzes the conversion of ATP to cAMP

Intracellular cAMP levels increase as less cAMP is broken down

• Epi/Nepi and other catecholamines synthesized in the adrenal glands stimulate BAR on cardiac muscle
  
• Stimulating G proteins activating AC within the cell membrane
• ATP --> cAMP --> AMP --> Adenosine
• Adenosine is highly lipid soluble and can readily diffuse through phospholipid bilayer into circulating blood system

1. cAMP increases --> increase in sympathetic response (increase in HR/contractility)

2. cAMP decreases --> sympathetic response decreases

3. Epi/Nepi will increase cAMP

• by increasing AC activity via G-proteins with link BAR to AC

4. Adenosine/Ach will decrease cAMP

• by decreasing AC activity via inhibitory G-proteins which link ADO receptors to AC

Local: During an MI there is damage to a portion of the heart muscle. The body tries to perseve the heart muscle by either increasing the O2 supply or decreasing the O2 demand. The heart also tries to decrease HR and O2 consumption at the local level by decreasing the production of ATP --> decreasing cAMP through adenosine

Systemic: Ach is stimulated from brain in response to baroreceptors in the aorta and signals in the kidneys.

Epinephrine: increased levels of cAMP are what cause the physiological effects of Epi

Epi -> BAR -> G proteins -> AC -> ATP -> cAMP -> AMP -> ADO

Norepinephrine: local response that yields similar results as Epi does b/c it causes stimulation of BAR --> increase of cAMP

Nepi -> BAR -> G proteins -> AC -> ATP -> cAMP -> AMP -> ADO

Adenosine: product of ATP metabolism after BAR is stimulated by Epi/Nepi. Too much stimulation causes ADO to diffuse lipid bilayer and stimulate ADO receptors on outside inhibiting the G proteins activating AC preventing further production of cAMP --> AMP --> ADO

Acetylcholine: released systemically by PNS stimulating Ach receptor inhibiting G-proteins stimulation of AC preventing further production of cAMP --> AMP --> ADO

Which of the following have local effects and which have more general effects:

• Acetylcholine
• Norepinephrine
• Epinephrine
• Adenosine

Epinephrine: general effects b/c adrenal medulla is only producer regulated by SNS

Norepinephrine: made locally at the site and only has local effects b/c it either diffuses away or participates in reuptake

Adenosine: only has local effects d/t very short half life

Acetylcholine: systemic effects, release is stimulated by PNS

1. What effect does Nepi have on intracellular cAMP production?

2. How does Nepi produce these effects?

1. Nepi increases cAMP production --> increased HR and contractility

2. Nepi --> BAR --> G-proteins --> AC --> ATP --> cAMP --> AMP --> ADO

1. What is cAMP broken down to?

2. What more readily traverses cellular membranes and why: 

• Adenosine
• Adenosine phosphate

1. cAMP --> AMP --> Adenosine

2. Adenosine more readily traverses the cell membrane because it is lipid soluble. The phosphate molecule causes the adenosine phosphate to be more polarized and water soluble.

Question 3.1 from book:

Which of the following statements concerning the parasympathetic nervous system is correct?

THE PARASYMPATHETIC DIVISION IS INVOLVED IN ACOMMODATION OF NEAR VISION, MOVEMENT OF FOOD AND URINATION

The PNS maintains essential body functions such as vision, movement of food and urination. It uses Ach as a neurotransmitter and it discharges as discrete fubers that are activated separately. The postganglionic fibers of the PNS are short compared to those of the SNS and the adrenal medulla is under the control of the SNS.

Question 3.2 from the book:

Which of the following is characteristic of parasympathetic stimulation?

CONTRACTION OF SPHINCTER MUSCLE IN THE IRIS OF THE EYE (MIOSIS)

The PNS is essential in the maintenance activities such as digestion and waste removal. Increased intestinal motility to facilitate peristalsis, relaxation of the urinary bladder sphincters to cause urination and increased bronchial secretions.