Answer: D. How body parts function Physiology studies how body parts and systems function.
Why does the body maintain homeostasis?
A Make values exactly constant
B Keep internal conditions within ranges
C Prevent system interactions
D Stop all internal changes
Answer: B. Keep internal conditions within ranges Homeostasis maintains internal conditions within ranges compatible with normal function.
What is a physiological set point?
A A patient treatment goal
B A fixed organ location
C Reference value for regulation
D A maximum heart rate
Answer: C. Reference value for regulation A set point is a reference value around which a physiological variable is regulated.
Why can a homeostatic variable change slightly?
A Normal ranges allow fluctuation
B Regulation never operates
C Organs stop communicating
D Every change is harmful
Answer: A. Normal ranges allow fluctuation Physiological variables normally fluctuate within a range rather than staying at one exact value.
What does a sensor do in a feedback loop?
A Produces the final response
B Stores the set point
C Compares values with a range
D Detects a physiological change
Answer: D. Detects a physiological change A sensor or receptor detects a physiological condition and sends information to a control center.
How does a control center guide regulation?
A Creates the initial stimulus
B Compares input with a range
C Detects every external sound
D Carries hormones to tissues
Answer: B. Compares input with a range The control center compares the sensed value with the regulated range and coordinates a response.
Which component carries out the response?
A Sensor
B Set point
C Effector
D Stimulus
Answer: C. Effector An effector produces the action that changes the regulated condition.
What is the usual effect of negative feedback?
A Reverses the initial deviation
B Stops all receptor signals
C Creates a new set point
D Amplifies the deviation
Answer: A. Reverses the initial deviation Negative feedback counteracts a change and helps return a variable toward its normal range.
How does positive feedback affect a change?
A Blocks all effectors
B Reverses it immediately
C Keeps it exactly constant
D Reinforces it until an endpoint
Answer: D. Reinforces it until an endpoint Positive feedback increases a change until a defined endpoint ends the loop.
Which process is a common positive feedback example?
A Routine temperature control
B Childbirth contractions
C Blood glucose regulation
D Water balance regulation
Answer: B. Childbirth contractions During childbirth, contractions intensify through positive feedback until delivery.
When body temperature rises, which response helps lower it?
A Reduced skin blood flow
B Increased muscle tone
C Sweating
D Shivering
Answer: C. Sweating Sweating promotes heat loss and helps return body temperature toward its regulated range.
What does shivering help the body do?
A Generate heat through muscle activity
B Reduce blood glucose
C Increase heat loss
D Lower metabolic activity
Answer: A. Generate heat through muscle activity Involuntary muscle activity during shivering generates heat.
When blood glucose rises, which hormone helps lower it?
A Glucagon
B Thyroxine
C Melatonin
D Insulin
Answer: D. Insulin Pancreatic beta cells release insulin when blood glucose is elevated, promoting glucose uptake by target tissues.
Which hormone raises blood glucose when levels fall?
A Oxytocin
B Glucagon
C Aldosterone
D Insulin
Answer: B. Glucagon Glucagon helps raise blood glucose when it is low, acting in opposition to insulin.
How do most endocrine hormones reach target tissues?
A Across synapses only
B Along bone surfaces
C Through the bloodstream
D Through airways
Answer: C. Through the bloodstream Endocrine hormones enter the blood and travel to cells with appropriate receptors.
What must a target cell have to respond to a hormone?
A A matching receptor
B A second nucleus
C A motor neuron
D A blood vessel
Answer: A. A matching receptor A hormone acts on target cells that have receptors able to recognize it.
Which sequence best represents a homeostatic loop?
A Hormone, organ, tissue, set point
B Sensor, organ, stimulus, cell
C Effector, tissue, organ, stimulus
D Stimulus, sensor, control center, effector
Answer: D. Stimulus, sensor, control center, effector A regulated change is detected by a sensor, processed by a control center, and acted on by an effector.
What does a negative-feedback response aim to restore?
A A permanent increase
B Regulated variable’s normal range
C A new organ system
D The original stimulus strength
Answer: B. Regulated variable’s normal range Negative feedback acts to return a variable toward its normal range.
Which transport moves particles down a concentration gradient without ATP?
A Active transport
B Endocytosis
C Passive transport
D Protein synthesis
Answer: C. Passive transport Passive transport moves substances down their concentration gradient without direct cellular energy input.
What is diffusion?
A Net movement down a gradient
B Transport against a gradient
C Vesicle release outside cells
D Water movement using ATP
Answer: A. Net movement down a gradient Diffusion is net movement of particles from higher to lower concentration.
Which substance moves during osmosis?
A Ions through a synapse
B Protein against a gradient
C Oxygen using a pump
D Water across a membrane
Answer: D. Water across a membrane Osmosis is the movement of water across a selectively permeable membrane.
Why does active transport require energy?
A It always moves water
B It can move substances uphill
C It occurs only outside cells
D It needs no membrane proteins
Answer: B. It can move substances uphill Active transport can move substances against their concentration gradients and uses cellular energy.
What does the sodium-potassium pump move?
A Calcium out, glucose in
B Water out, oxygen in
C Sodium out, potassium in
D Potassium out, sodium in
Answer: C. Sodium out, potassium in The sodium-potassium pump uses ATP to move sodium out of cells and potassium into them.
Which membrane feature helps control what enters a cell?
A Selective permeability
B Permanent pore size
C Rigid mineral coating
D Open passage for everything
Answer: A. Selective permeability The cell membrane is selectively permeable, controlling movement of substances into and out of cells.
What is ATP’s main role in cellular physiology?
A Store genetic instructions
B Carry oxygen in blood
C Form tissue membranes
D Provide usable cellular energy
Answer: D. Provide usable cellular energy ATP transfers usable energy to cellular processes.
When does a neuron typically initiate an action potential?
A When the membrane is destroyed
B When threshold is reached
C Only during sleep
D Whenever a hormone binds
Answer: B. When threshold is reached A sufficient change in membrane potential can reach threshold and initiate an action potential.
Where does an action potential travel in a neuron?
A Inside a hormone gland
B Across a blood vessel
C Along the axon
D Through the nucleus only
Answer: C. Along the axon Action potentials propagate along a neuron’s axon.
What crosses a chemical synapse to signal another cell?
A Neurotransmitter
B Hemoglobin
C Insulin only
D Cerebrospinal fluid
Answer: A. Neurotransmitter Neurotransmitters are released from one neuron and diffuse across the synaptic cleft.
How can a neurotransmitter affect a target neuron?
A Replace its membrane
B Carry oxygen to it
C Enter its nucleus directly
D Bind to its receptor
Answer: D. Bind to its receptor A neurotransmitter binds receptors on the target cell and changes its signaling state.
Which structure receives many incoming signals on a neuron?
A Node of Ranvier
B Dendrites
C Axon terminals
D Myelin sheath
Answer: B. Dendrites Dendrites receive input from other cells and convey graded signals toward the neuron’s cell body.
Where does external respiration occur?
A Inside body tissues
B Within the stomach
C At the lung alveoli
D In kidney tubules
Answer: C. At the lung alveoli External respiration is gas exchange between alveoli and pulmonary capillary blood.
Which gases cross the respiratory membrane?
A Oxygen and carbon dioxide
B Water and sodium
C Insulin and oxygen
D Nitrogen and glucose
Answer: A. Oxygen and carbon dioxide Oxygen and carbon dioxide diffuse across the respiratory membrane.
Where does oxygen move during external respiration?
A Blood into stomach
B Blood into alveoli
C Tissues into alveoli
D Alveoli into blood
Answer: D. Alveoli into blood Oxygen diffuses from alveolar air into pulmonary capillary blood.
What is internal respiration?
A Air movement into lungs
B Gas exchange at body tissues
C Gas exchange in alveoli
D Oxygen transport by hemoglobin
Answer: B. Gas exchange at body tissues Internal respiration is the exchange of gases between systemic blood and body tissues.
Why do respiratory gases diffuse across membranes?
A Muscle contraction only
B Hormone receptors
C Partial-pressure gradients
D ATP-powered pumps
Answer: C. Partial-pressure gradients Differences in partial pressure drive oxygen and carbon dioxide diffusion across respiratory membranes.
Which blood component carries most oxygen?
A Hemoglobin in red cells
B Glucose in plasma
C Platelets in plasma
D Albumin in white cells
Answer: A. Hemoglobin in red cells Most oxygen in blood binds to hemoglobin inside red blood cells.
What is pulmonary ventilation?
A Blood movement through lungs
B Gas exchange at tissues
C Food movement through gut
D Air movement into and out
Answer: D. Air movement into and out Pulmonary ventilation is the movement of air into and out of the lungs.
What does perfusion describe in the lungs?
A Food flow through stomach
B Blood flow through capillaries
C Hormone flow through glands
D Airflow through bronchi
Answer: B. Blood flow through capillaries Perfusion is blood flow through capillary networks where exchange can occur.
Why is carbon dioxide removed from the body?
A It forms the cell membrane
B Main blood protein
C It is cellular metabolism waste
D It is blood’s main protein
Answer: C. It is cellular metabolism waste Carbon dioxide is produced by cellular metabolism and is removed through the lungs.
Which organ system adjusts water loss by changing urine concentration?
A Urinary system
B Integumentary system
C Skeletal system
D Digestive system
Answer: A. Urinary system The kidneys adjust water reabsorption and urine concentration to help regulate body water.
What does antidiuretic hormone promote in the kidneys?
A Calcium loss in sweat
B Protein digestion
C Glucose release into urine
D Water reabsorption
Answer: D. Water reabsorption ADH signals the kidneys to recover more water from forming urine.
What can rising blood solute concentration trigger?
A Increased bone growth
B Thirst
C Reduced water seeking
D Lower breathing rate
Answer: B. Thirst Osmoreceptors detect increased blood concentration and can trigger thirst.
How do kidneys help maintain homeostasis?
A Exchange gases with air
B Produce nerve impulses
C Regulate water and wastes
D Digest dietary proteins
Answer: C. Regulate water and wastes Kidneys excrete wastes and help regulate water and electrolyte balance.
Which control pattern commonly regulates hormone secretion?
A Negative feedback
B Positive feedback only
C No receptor involvement
D Random signaling
Answer: A. Negative feedback Many hormones are regulated by feedback loops, most commonly negative feedback.
Why can one hormone cause different effects in different tissues?
A All cells have identical receptors
B Blood moves in one direction
C Hormones change their own structure
D Target cells differ in response
Answer: D. Target cells differ in response The response to a hormone depends on the target cell and its receptor-mediated pathways.
What is downregulation in hormone signaling?
A More hormone release
B Fewer target-cell receptors
C Faster nerve conduction
D Increased blood flow
Answer: B. Fewer target-cell receptors When hormone exposure is persistently high, target cells may reduce receptor numbers and become less responsive.
How does the body respond when a feedback loop reaches its set point?
A The sensor stops existing
B The organ permanently changes
C Effector response decreases
D The stimulus always grows
Answer: C. Effector response decreases As the regulated condition returns toward its range, the corrective response is reduced.
What distinguishes a positive-feedback loop from negative feedback?
A It intensifies the original change
B It works without stimuli
C It reverses any change
D It cannot use effectors
Answer: A. It intensifies the original change Positive feedback amplifies a change, while negative feedback counteracts one.
Why can ventilation and perfusion both affect gas exchange?
A Hormones must bind first
B Food must be digested
C Bones must release calcium
D Air and blood must meet
Answer: D. Air and blood must meet Efficient lung gas exchange depends on ventilation bringing air to alveoli and perfusion bringing blood to their capillaries.
What is a likely result when oxygen diffuses into pulmonary blood?
A The lungs stop ventilating
B Blood oxygenation increases
C The heart stops pumping
D Carbon dioxide production stops
Answer: B. Blood oxygenation increases Oxygen entering pulmonary capillary blood increases its oxygen content.