Exam Overview #3 Review

Practice flashcards for Exam 3 review covering Modules 9 through 13 of the physiology curriculum.

What does the acronym S.A.M.E. stand for in the context of the nervous system?

Sensory Afferent Motor Efferent

Where do motor neurons transport nerve impulses?

From the CNS to muscles or glands

Why are motor neurons considered multipolar?

They have many dendrites and a single axon

What are the primary effects of motor neuron signals?

Causing muscle fibers to contract or glands to secrete

Where do sensory neurons take nerve impulses from?

From sensory receptors to the CNS

What is the structural classification of a sensory neuron?

Unipolar

Give an example of a simple sensory receptor.

A naked nerve ending (pain receptor)

Where do interneurons, or association neurons, occur?

Entirely within the CNS

What is the structural classification of interneurons?

Multipolar

What is the primary function of interneurons?

To convey nerve impulses between various parts of the CNS

Which type of synapse is the most common in the body?

Chemical synapses

What do chemical synapses use to transmit signals?

Neurotransmitters

Is the signal transmission in a chemical synapse unidirectional or bidirectional?

Unidirectional

List common neurotransmitters mentioned for chemical synapses.

ACh, NE, Dopamine, Serotonin, GABA, Glutamate

Through what structure do electrical synapses allow direct ion flow?

Gap junctions

Is transmission in electrical synapses faster or slower than in chemical synapses?

Very fast

What is the directionality of signal flow in electrical synapses?

Bidirectional

List the locations where electrical synapses are found.

Some brainstem nuclei, smooth muscle, cardiac muscle, and the retina

In the parasympathetic preganglionic neuron, what is the neurotransmitter released?

ACh

What type of receptor is found on the parasympathetic postganglionic neuron?

Nicotinic receptors

What neurotransmitter is released by the parasympathetic postganglionic neuron?

ACh

What type of receptor is targeted by the parasympathetic postganglionic neuron?

Muscarinic receptors

In the sympathetic preganglionic neuron, what neurotransmitter is always released?

ACh

What receptor type does the sympathetic preganglionic neuron release ACh onto?

Nicotinic receptors

What neurotransmitter is released by most sympathetic postganglionic neurons?

Norepinephrine (NE)

Which receptors are targeted by the sympathetic postganglionic neuron releasing NE?

$\alpha$ and $\beta$ receptors

What are the somatic afferent receptors for touch, vibration, and pressure?

Meissner, Merkel, Pacinian, and Ruffini

What are the specialized mechanoreceptors for body position?

Muscle spindle and GTO (Golgi Tendon Organ)

What type of receptors are free nerve endings?

Thermoreceptors (and pain receptors)

Which nerve fibers are associated with nociceptors and pain transmission?

A-delta and C fibers

What is the sympathetic effect on the heart?

$\uparrow$ HR and $\uparrow$ contractility

Which specific receptor type mediates the sympathetic effect on the heart?

$$\beta 1$$

What is the sympathetic effect on the lungs?

Bronchodilation

Is the sympathetic effect on the lungs excitatory or inhibitory?

Inhibitory

What receptor type is associated with sympathetic bronchodilation?

$$\beta 2$$

What is the sympathetic effect on blood vessels in the skin and GI tract?

Vasoconstriction

What is the sympathetic effect on blood vessels in skeletal muscle?

Vasodilation

Which receptor mediates sympathetic vasodilation in skeletal muscle?

$$\beta 2$$

What is the sympathetic effect on GI tract motility and sphincter tone?

Mostly inhibitory

What is the sympathetic effect on the eye pupil?

Mydriasis (dilation)

What is the sympathetic effect on the liver?

$\uparrow$ Glucose release

What is the sympathetic effect on adipose tissue?

Lipolysis

What neurotransmitter is used by the sympathetic system to trigger sweating?

ACh

What receptor type is found on sweat glands for the sympathetic system?

Muscarinic

What is the parasympathetic effect on the heart?

$\downarrow$ HR and AV conduction

Which specific receptor type mediates the parasympathetic effect on the heart?

$$M_2$$

What is the parasympathetic effect on the lungs?

Bronchoconstriction

What is the parasympathetic effect on GI motility and secretions?

$\uparrow$ Motility and secretions

What is the parasympathetic effect on the bladder detrusor muscle?

Contract detrusor

What is the parasympathetic effect on the eyes?

Miosis (constriction) & near vision

What are the mechanical digestion processes in the mouth?

Mastication (chewing) and tongue mixing

What enzyme in saliva starts carbohydrate digestion?

Salivary amylase (ptyalin)

What chemical digestion of fat begins in the mouth?

Lingual lipase (minor)

What is the function of the pharynx and esophagus in digestion?

Passage for food from mouth to stomach via peristalsis

What are the mechanical digestion activities of the stomach?

Churning and mixing bolus into chyme

What is the role of $HCI$ in the stomach?

Creates acidic medium, kills microbes, and activates pepsinogen

Which enzyme starts protein digestion in the stomach?

Pepsin

What are proteins broken into by pepsin?

Peptones

What is the rhythmic contraction that mixes food in the small intestine?

Segmentation

Which pancreatic enzymes break down proteins into peptides and amino acids?

Trypsin, chymotrypsin, and carboxypeptidase

What enzyme from the pancreas breaks down fats into fatty acids and monoglycerides?

Pancreatic lipase

Where is bile stored and what is its function?

Stored in the gallbladder; it emulsifies fats

List the disaccharidases found in the intestinal brush border.

Maltase, lactase, and sucrase

What is the process of mixing contents in the large intestine?

Haustral churning

What are the synthesis products of bacteria in the large intestine?

Vitamin K and B complex

Where is the main site of absorption in the GIT?

Small intestine

In what form are carbohydrates absorbed into the blood capillaries?

Monosaccharides (glucose, fructose, galactose)

In what form are proteins absorbed into the blood?

Amino acids

How are fats absorbed into the lymphatic system?

As chylomicrons into lacteals

What are the primary absorptive functions of the large intestine?

Water and electrolytes

What is the splanchnic circulation?

Blood flow through the gut, spleen, pancreas, and liver via the portal vein

What is the function of reticuloendothelial cells in the liver sinusoids?

Removing bacteria and other matter from the GIT blood

Where does blood from the hepatic veins empty?

The Vena cava

During active nutrient absorption, how much can blood flow in the villi increase?

As much as eightfold

What is 'autoregulatory escape' in gastrointestinal blood flow?

Local metabolic vasodilator mechanisms override sympathetic vasoconstriction during ischemia

What cell type secretes the hormone Gastrin?

G cells of the antrum, duodenum, and jejunum

What are the major stimuli for Gastrin secretion?

Protein, distention, and nerves

What are the main actions of Gastrin?

Stimulates gastric acid secretion and mucosal growth

Where is Cholecystokinin (CCK) secreted from?

I cells of the duodenum, jejunum, and ileum

What triggers the release of CCK?

Protein, Fat, and Acid

What effect does CCK have on the gallbladder?

Stimulates contraction

What effect does CCK have on gastric emptying?

Inhibits gastric emptying

Where is Secretin produced?

S cells of the duodenum, jejunum, and ileum

What is the primary stimulus for Secretin secretion?

Acid and Fat

What does Secretin stimulate the pancreas to release?

Bicarbonate ($HCO_3^-$)

Where is Gastric Inhibitory Peptide (GIP) secreted from?

K cells of the duodenum and jejunum

What is the dual action of GIP (Glucose-dependent insulinotropic peptide)?

Stimulates insulin release and inhibits gastric acid secretion

What is the definition of chyme?

The semi-liquid mixture of food and stomach secretions that passes to the intestine

What are the hunger contractions in the stomach called?

Peristaltic contractions

What is the pH threshold for Metabolic Alkalosis?

$$> 7.45$$

What is the primary change in Metabolic Acidosis?

Loss of bicarbonate or increase in acid ($\downarrow HCO_3^-$)

What is the compensation for Respiratory Acidosis?

Renal compensation by increasing $HCO_3^-$ retention

What are classic examples of Metabolic Acidosis?

Diabetic ketoacidosis (DKA), lactic acidosis, and severe diarrhea

List two causes of Respiratory Acidosis mentioned in the table.

COPD and Opioid overdose

What is the primary change in Respiratory Alkalosis?

Decrease in $CO_2$ due to hyperventilation

Which acid-base disorder is associated with NG suction and vomiting?

Metabolic Alkalosis

What process allows lipases to divide lipids into fatty acids and monoglycerides?

Emulsification by bile salts

How do monoglycerides and fatty acids enter absorptive cells in the SI?

Through micelles

How are fat-soluble vitamins absorbed?

In the same manner as lipids (via micelles/chylomicrons)

List the three specific liver functions in fat metabolism.

1. Oxidation of fatty acids 2. Synthesis of cholesterol/phospholipids 3. Synthesis of fat from proteins/carbs