Exam 4 study questions [ EXAM #4 ]

Question 1

1st and 2nd lines of defense: Be able to describe the purpose of the 1st and 2nd lines of defense. Discuss the components of each line of defense and how they function to keep you healthy and minimize illness.

Answer 1

1st line of defense = physical barriers (skin, mucosa)

2nd line of defense = phagocytes, NK cells, anti-microbial proteins , inflammation

Question 2

Inflammatory response: Describe the events that take place during the inflammatory response. You should discuss chemotaxis, margination and diapedesis. The role of mast cells should be described and the events leading to the cardinal signs of inflammation should be explained.

Answer 2

redness = increased blood flow

heat = increased blood flow and metabolism

swelling = capillaries leak protein-rich fluid into interstitial space

pain = stimulation of pain receptors due to compression

mast cells are proinflammatory and chemotactic to other immune cells

Question 3

Fever: Explain what a fever is. Be able to identify the beneficial effects of a fever. When does it become dangerous and why?

Answer 3

widespread response to infection

Pyrogens: chemicals affect hypothalamus (body thermostat) - reset body temp higher

beneficial =
• ↓ bacteria and virus reproduction
• Increase metabolic rate of cells

dangerous =
Can denature enzymes (proteins)

Question 4

Primary and secondary immune response: Describe immunologic memory and the primary and secondary response to antigen exposure (including the speed and duration of the response, lag periods, plasma cells, memory B cells, the specific antibodies produced, general amounts (titers) and when etc.). Explain how this relates to the basis of immunizations.

Answer 4

PRIMARY IMMUNE RESPONSE
• Takes time to develop (SLOW)
• Antigens activate B cells
• Plasma cells differentiate
• Antibody titer (level) slowly rises 1-2 weeks after lag phase

SECONDARY IMMUNE RESPONSE
• FAST, little lag phase
• Activates memory B cells
• lower antigen concentrations than original B cells
• Secrete antibodies in massive quantities

Question 5

Deglutition: Describe the events that take place within the three phases of deglutition (swallowing) and how they are controlled.

Answer 5

1. Voluntary (buccal) phase
   • VOLUNTARY
   • controlled by cerebral cortex
   • bolus formed and moved toward oropharynx

2. Pharyngeal phase
   • INVOLUNTARY
   • bolus arrives at oropharynx and stims swallowing reflex (tactile receptors)
   • bolus moves towards esophagus

3. Esophageal phase
   • INVOLUNTARY
   • peristalsis pushes bolus down esophagus
   • gastroesophageal sphincter relaxes, food enters stomach

Question 6

Epithelial cells of the stomach: Distinguish among the 5 different epithelial cells in the stomach. Describe the functions of each type and identify whether they are exocrine or endocrine in function.

Answer 6

SURFACE MUCOUS CELLS =
• alkaline mucus layer
• protection from acid and gastric enzymes

• MUCOUS NECK CELLS: produce acidic mucus

PARIETAL CELLS (exocrine) =
• Secrete intrinsic factor and hydrochloric acid
 • Activation of pepsinogen into active pepsin (protein digestion)

CHIEF CELLS (exocrine) =
• Secrete inactive pepsinogen and gastric lipase 

G CELLS (endocrine)
• Secrete gastrin hormone into blood

Question 7

Stomach protection: Describe the protective mechanisms that help to protect the stomach from its own acidic environment so that the stomach does not digest itself.

Answer 7

1. alkaline mucus secretory sheet
2. epithelium is constantly regenerating.
3. tight junctions prevent HCl from leaking into underlying tissue.
4. H and Cl released as separate ions and don’t bind until out of cells and into lumen of stomach.

Question 8

Digestive secretion and motility regulation: Describe the regulation of digestive secretion and motility in the stomach (cephalic, gastric, and intestinal). Explain what is responsible for each phase, when they occur, and what takes place during each.

Answer 8

CEPHALIC

• parasympathetic NS reflex via vagus nerve
• ↑ saliva
• ↑ in gastric juice production
• ↑ contractile force (growl)

GASTRIC

• when bolus reaches stomach
• ~2/3 gastric juice secretion and ↑ mixing
• forms chyme and empties into small intestines

INTESTINAL

• Begins when chyme enters small intestines
• CCK, secretin production
• Inhibit gastrin release

Question 9

Absorption in the small intestines: Describe the multiple levels of anatomy within the small intestines that increase surface area and therefore increase nutrient absorption.

Answer 9

Circular folds : slows chyme down, more SA:V for absorption

Villi: velvety surface
• Absorptive and goblet cells

Microvilli: fuzzy brush-border full of enzymes for final digestion into capillaries and lacteals

Question 10

Defecation reflex: Describe the events that take place during the defecation reflex.

Answer 10

Stretch of rectum stimulates baroreceptors

Parasympathetic reflex → contraction of rectal walls, relaxation of internal anal sphincter
• Involuntary but raises conscious awareness

Voluntary relaxation of ext. anal sphincter, push → defecation

Question 11

Digestion throughout the GI tract: Be able to describe the specific digestion and absorption of carbs, lipids, nucleic acids and proteins throughout each part of the GI tract. You must be able to identify the different enzymes involved, where they there are released from, where they are active and what specific effects they have on the food/chyme they act upon.

Answer 11

flow chart