BIOL 118 UW Exam one

What is physiology?

The study of how the body and its parts function.

What are the 6 levels of organization in the human body?

Chemical → cellular → tissue → organ → organ system → organismal.

What is homeostasis?

Maintaining a relatively stable internal environment despite change.

What are the basic parts of a homeostatic control system?

Stimulus → receptor → control center → effector → response.

What is a stimulus?

A change in a variable that disrupts homeostasis.

What does a receptor do?

Detects a change in a variable.

What does the control center do?

Processes information and determines the response.

What does an effector do?

carries out the response that changes the variable back towards its normal range

What is negative feedback?

A response that opposes a change and moves a variable back toward normal.

What is positive feedback?

A response that amplifies the original change.

What does pH measure?

Hydrogen ion concentration.

What is the equation for pH?

pH = −log[H⁺].

What happens to pH when H⁺ increases?

pH decreases and the solution becomes more acidic.

What happens to pH when H⁺ decreases?

pH increases and the solution becomes more basic.

What is the normal blood pH range?

7.35–7.45.

What is acidosis?

Blood becoming too acidic; pH is too low.

What is alkalosis?

Blood becoming too basic; pH is too high.

What are common causes of acidosis from lecture (Eugene’s story)?

Diarrhea, kidney failure, and respiratory problems such as emphysema.

What are common causes of alkalosis from lecture (Eugene’s stroy)?

Vomiting and hyperventilation.

What is a buffer?

A system that limits changes in pH when acid or base is added.

What is the major buffer system discussed in class?

The carbonic acid–bicarbonate buffer system.

What is the bicarbonate buffer equation?

CO₂ + H₂O ⇌ H₂CO₃ ⇌ HCO₃⁻ + H⁺.

What happens when extra H⁺ is added to the bicarbonate system?

The reaction shifts toward carbonic acid, reducing free H⁺.

What happens when H⁺ decreases?

Carbonic acid can dissociate and release H⁺.

Which two organ systems strongly regulate blood pH?

Respiratory and urinary systems.

How does increased ventilation affect CO₂?

More CO₂ is removed from the blood.

How does increased ventilation affect blood pH?

CO₂ falls, H⁺ falls, and pH rises.

How does decreased ventilation affect blood pH?

CO₂ rises, H⁺ rises, and pH falls.

Why can hyperventilation cause alkalosis?

Too much CO₂ is removed, lowering H⁺ and increasing pH.

What is Le Chatelier's principle?

An equilibrium shifts to oppose an imposed change.

How does Le Chatelier's principle apply to blood pH?

Changes in CO₂ or H⁺ shift the bicarbonate reaction to oppose the disturbance.

What are chemoreceptors?

Receptors that detect chemical changes related to variables such as blood pH.

What is ingestion?

Taking food into the mouth.

What is mechanical digestion?

Physical breakdown or processing of food.

What is chemical digestion?

Chemical breakdown of food molecules.

What is secretion in digestion?

Movement or release of substances into the digestive tract.

What is absorption?

the movement of digested nutrients from the digestive tract (gastrointestinal) into the blood or lymph

What is excretion?

Removal of waste products from the body.

What is a bolus?

A mass of chewed food prepared for swallowing.

What is chyme?

A mixture of partially digested food and stomach acid/secretions.

What does the mouth do in digestion?

Breaks up food particles.

What do salivary glands do?

Produce saliva that moistens and lubricates food.

What enzyme in saliva begins carbohydrate digestion?

Amylase.

What does the pharynx do?

Helps with swallowing.

What does the esophagus do?

Transports food to the stomach.

What is peristalsis?

Wave-like muscular contractions that move food through the digestive tract.

What happens behind the bolus during esophageal peristalsis?

Circular muscles contract.

What do longitudinal muscles do during peristalsis?

They contract and help push the food mass forward.

What does the stomach do mechanically?

Stores, churns, mixes, and grinds food.

What does the stomach do chemically?

Uses acid and enzymes to begin protein digestion.

What is propulsion in the stomach?

Peristaltic waves move food toward the pylorus.

What is grinding in the stomach?

Strong peristaltic mixing near the pylorus breaks chyme into smaller particles.

What is retropulsion?

Chyme is pushed backward into the stomach when the pyloric valve closes.

Why does retropulsion occur?

It increases mixing and mechanical breakdown of stomach contents.

What does the pyloric region do during stomach emptying?

It allows small amounts of chyme into the duodenum.

What hormone secreted by the stomach activates gastric glands?

Gastrin.

What does hydrochloric acid do in the stomach?

Helps convert pepsinogen into pepsin.

What is pepsin?

An enzyme that breaks down proteins.

What does stomach mucus do?

Protects the stomach lining from acid.

What is intrinsic factor?

A stomach glycoprotein needed for vitamin B12 absorption.

Why is vitamin B12 important?

It is needed for DNA synthesis and hemoglobin production.

What is the main site of nutrient absorption?

The small intestine.

What is the main site where digestion is completed?

The small intestine.

What structural features increase small-intestine surface area?

Plicae/folds, villi, and microvilli.

Why do plicae, villi, and microvilli improve absorption?

They greatly increase small-intestinal surface area, allowing more nutrients to be absorbed

What do capillaries inside intestinal villi do?

Carry absorbed nutrients into the blood.

What is a lacteal?

A lymphatic vessel in a villus involved in absorption of fats.

What does the large intestine mainly do?

Reabsorbs some water and ions and forms/stores feces.

What does the rectum do?

Stores and expels feces.

What does the anus do?

Provides the opening for elimination of feces.

Where is bile produced?

The liver.

Where is bile stored and concentrated?

The gallbladder.

What is the digestive function of bile salts?

They emulsify fats.

Is bile acting mechanically or chemically in fat digestion?

Mechanically; it breaks large fat droplets into smaller droplets.

What does emulsification mean?

Breaking large fat droplets into smaller droplets.

Why does emulsification help fat digestion?

It increases the surface area available to digestive enzymes.

What does the pancreas secrete into the digestive tract?

Bicarbonate and digestive enzymes.

What is the function of pancreatic bicarbonate?

It helps neutralize acidic chyme from the stomach.

What does pancreatic protease digest?

Proteins.

What does pancreatic lipase digest?

Lipids/fats.

What does pancreatic amylase digest?

Carbohydrates.

How are pancreatic enzymes different from bile salts?

Enzymes chemically break bonds; bile mechanically emulsifies fats.

Why are bile and pancreatic secretions added to the duodenum?

They assist digestion after acidic chyme enters the small intestine.

What does the liver do besides producing bile?

Stores nutrients and carries out many metabolic functions.

What does the gallbladder do?

Stores and concentrates bile.

What is pancreatitis?

Inflammation of the pancreas.

What are the major pancreatitis risk factors?

About 40% gallstones, 30% alcohol, and 2–5% high triglycerides.

What health conditions are associated with pancreatitis?

Diabetes, obesity, and smoking.

What happens to pancreatic cells during pancreatitis?

Inflammation damages pancreatic cells.

What can damaged pancreatic cells release into the blood?

Digestive enzymes such as lipase and amylase.

Why might blood lipase or amylase increase in pancreatitis?

Damaged pancreatic cells release/leak these enzymes into the bloodstream.

What is health equity?

Attainment of the highest level of health for all people.

What does achieving health equity require?

Valuing everyone equally and addressing avoidable inequalities and injustices.

What disparities should health-equity efforts work to eliminate?

Health and healthcare disparities.

What kinds of factors can influence health according to the equity framework?

Health, knowledge, standard of living, community, and social factors.

How can structural discrimination affect health?

It can influence social conditions and contribute to health disparities.

What is one difference between a bolus and chyme?

A bolus is swallowed food; chyme is partially digested food mixed with stomach secretions.

How does esophageal peristalsis differ from stomach grinding?

Peristalsis mainly transports food; stomach grinding mechanically mixes and breaks it down.

How does stomach propulsion differ from retropulsion?

Propulsion moves contents toward the pylorus; retropulsion pushes them back for more mixing.

Why is smooth muscle important in digestion?

Its contractions transport, mix, and mechanically break down food.