Cellular Physiology – Chapter 1

Question-and-Answer flashcards covering major definitions, mechanisms, and clinical concepts from Chapter 1 Cellular Physiology lecture notes.

What does anatomy study?

The structure and description of the human body.

What does physiology study?

The biological functions and processes of the human body under basal (normal) conditions.

How does cellular physiology differ from systemic physiology?

Cellular physiology examines biochemical and biophysical processes inside individual cells, whereas systemic physiology studies regulation of body-wide processes via homeostatic reflexes.

What is pathophysiology?

The study of abnormal biochemical and biophysical processes that occur in disease, used for diagnosis and treatment.

Define homeostasis.

The dynamic constancy of the internal physiological environment while buffering external challenges; the body’s ability to maintain relatively constant internal conditions.

List the four basic components of a feedback control system.

Stimulus, receptor (sensor), control center, effector.

In a negative feedback system, how does the response relate to the initial stimulus?

The response opposes or negates the original stimulus.

Give one physiologic example of a negative feedback loop.

Blood pressure regulation: decreased blood volume → decreased pressure → baroreceptors → brain → vessel constriction & increased heart rate to restore pressure.

In a positive feedback system, how does the response relate to the stimulus?

The response amplifies or promotes the initial stimulus.

Name two physiologic processes that operate via positive feedback.

Childbirth (oxytocin-mediated uterine contractions) and blood coagulation.

How are positive feedback loops ultimately stopped?

By removal of the original stimulus or activation of an external inhibitory mechanism (e.g., delivery of the baby ends cervical stretch).

Describe the amphipathic nature of the plasma membrane.

It has hydrophilic phosphate heads facing aqueous environments and hydrophobic fatty-acid tails facing inward, forming a bilayer.

Which part of a phospholipid is hydrophilic?

The phosphate head.

Which part of a phospholipid is hydrophobic?

The fatty acid tail.

What is simple diffusion?

Passive, unassisted movement of molecules from high to low concentration across the membrane.

How does facilitated diffusion differ from simple diffusion?

It still moves substances down their concentration gradient but requires specific transport proteins (channel-mediated or carrier-mediated).

What is primary active transport?

Carrier proteins pump molecules against their gradient using direct cellular energy (ATP).

What is secondary active transport?

Downhill movement of one molecule drives uphill movement of another, using the gradient created by primary active transport (indirect ATP use).

Define phagocytosis.

A type of endocytosis in which the cell engulfs large particles by extending pseudopods to form a phagosome.

Define pinocytosis.

A type of endocytosis in which the cell engulfs extracellular fluid and dissolved solutes in small vesicles; “cell drinking.”

What is exocytosis?

Vesicular transport process that releases substances from the cell into the extracellular environment; basis for most secretion.

Explain osmosis.

The net movement of water (solvent) through a semipermeable membrane from a region of higher water concentration (lower solute) to lower water concentration (higher solute).

Describe a hypotonic solution relative to a cell.

Lower solute concentration than the cell’s interior; water enters the cell, possibly causing swelling or lysis.

Describe a hypertonic solution relative to a cell.

Higher solute concentration than the cell’s interior; water leaves the cell, causing shrinkage (crenation).

What happens to red blood cells in an isotonic solution?

They retain normal shape because there is no net movement of water.

What determines tonicity?

Only non-penetrating solutes that cannot cross the membrane and therefore exert osmotic pressure.

State the percentage contributions of genetics vs. epigenetics to health and aging suggested by current research.

Approximately 20% genetics and 80% epigenetically modifiable factors (lifestyle & environment).

Define epigenetics.

The study of how lifestyle and environmental signals modify gene activity, switching genes on or off without changing the DNA sequence.

Why are proteins considered the “business end” of physiology rather than DNA itself?

Proteins execute cellular and organ functions—muscle contraction, neural activity, nutrient processing, oxygen transport—while DNA only encodes their production.

Give three lifestyle factors that can induce epigenetic changes.

Exercise, nutrition, stress (also acceptable: trauma, substance abuse, social engagement).