PHYL

Question 1

Muscarinic antagonist

Answer 1

Suppresses salivary and bronchial secretions before surgery

Question 2

Adrenaline

Answer 2

● Increased heart rate and leads to general vasoconstriction in the treatment of acute cardiac failure

Question 3

Nicotinic antagonist

Answer 3

● Reduces the effects of sympathetic and parasympathetic nervous system → lethal

Question 4

Beta 2 agonist

Answer 4

● Dilates bronchioles in the treatment of asthma without undesirably stimulating the heart

Question 5

Beta 1 antagonist

Answer 5

● Selectively blocks beta 1 adrenergic receptors thereby reducing the sympathetic effects on the heart
● Reduces heart rate in the treatment of hypertension

Question 6

Describe regulation of GIT functions

INVOLTUNARY

Answer 6

External stimulus (such as the sight, smell and taste of food) stimulates the central nervous system – LONG REFLEX

Internal stimuli (chemoreceptors, osmoreceptors, mechanoreceptors), can stimulate the central nervous system which affects the local nerve plexus, but can also directly stimulate the local nerve plexus through short reflexes. _ SHORT

Question 7

SWALLOWING REFLEX

Answer 7

1. Bolus is formed
2. Brainstem closes the pharyngoesophageal sphincter so food doesn’t go up the nose
3. Glottis closes so that food doesn’t go down the trachea
4. Peristalsis pushes down the food
   Sphincter of the stomach opens up due to mechanoreceptors

Question 8

State the functions of the stomach

Answer 8

1. Stores ingested food and begins digestion
2. Secretes HCl and enzymes that begin protein digestion, also produces intrinsic factor
3. Mixes food bolus and produces chyme
   a. Mechanical digestion is break up of food particles
   b. Chemical digestion

Question 9

Describe how HCl is produced

Answer 9

● HCl is produced by parietal cells
● Secondary active transport brings Cl- from the plasma into the parietal cells
● Passive diffusion of Cl from parietal cell to the lumen
● Active transport of H+ from the parietal cell to the lumen

Question 10

Describe the mechanisms that allow mucus to be a protective barrier

Answer 10

1.	Impermeable mucosal cells
●	Luminal membranes are impermeable to H+
2.	Tight junctions
●	Prevent HCl from penetrating
3.	Mucous coat
●	Physical barrier to HCl
4.	Chemical barrier
●	HCO3- neutralizes HCl

Question 11

*** Describe the regulation of gastric secretion

Answer 11

● Neural control: acetylcholine
○ Released by intrinsic nerve plexuses within the stomach under the control of short local reflexes and vagal stimulation
● Hormonal control
○ ECl cells: secrete histamine among the parietal and chief cells (oxyntic mucosa)
○ G Cells: secrete gastrin into the blood stream
○ D cells: secrete somatostatin in the response to the acid

Question 12

The control of gastric secretion involves three phases

Answer 12

1. Cephalic phase
   ● Factors arising before food reaches the stomach
   ● Stimulated by seeing, smelling, tasting, chewing food
   ● Activates the autonomic nervous system
   ● Acetylcholine is released and activates the chief cells, parietal cells, ECl and G cells
2. Gastric phase
   ● Factors result from food in the stomach
   ● Once food reaches the stomach
   ● G cells are activated by short reflexes and produce gastrin
   ● Gastrin is released into the bloodstream and activates chief cells, parietal cells and ECl cells
   ● More HCl is produced by the parietal cells and more pepsinogen is produced by chief cells once food reaches the stomach
   ● Histamine is produced and is final drive of the whole system → most important step
3. Intestinal phase
   ● Factors in the duodenum after food has left the stomach
   ● D cells sense the change in pH and produce somatostatin