BIOL 155 M1

L1-14, UBC

How does structure relate to function in anatomy and physiology?

Structure determines (or predicts) function—morphology and material properties dictate what a structure can do.

What are trade-offs in anatomical structures?

Trade-offs occur when a single structure must balance multiple competing functions, leading to compromises in performance.

What is homeostasis and why is it important?

Homeostasis is the ability to maintain a stable internal environment. It preserves body function by keeping physiological variables within narrow limits.

What are the three required components of homeostatic regulation?

Sensor/Receptor – detects change
Integrator – compares input to a set point
Effector – produces a response to restore balance

How does allostasis differ from homeostasis?

Allostasis is the ability to adjust set points or behaviours to meet changing conditions, whereas homeostasis maintains stability around a fixed set point.

What is physiological allostasis vs. behavioural allostasis?

Physiological: automatic resetting of set points during specific states (e.g., fever, pregnancy).
Behavioural: deliberate behaviours to meet future needs (e.g., storing food, exercising for resilience).

Why is allostasis considered “feed-forward”?

Both forms anticipate future needs rather than just reacting to current deviations.

How do negative and positive feedback loops differ?

Negative feedback: returns a variable toward its set point (stability).
Positive feedback: amplifies deviation, pushing the variable further from set point (escalation)

Define hydrophilic.

Water-loving; interacts well with water (polar/charged molecules).

Define hydrophobic.

Water-fearing; does not interact well with water (non-polar molecules).

Define hydration sphere.

A shell of water molecules that surrounds ions or polar molecules in solution.

Define colloid.

A mixture where large molecules remain suspended in liquid without settling (e.g., cytoplasm).

Define organic molecule.

Molecule containing carbon and hydrogen, usually associated with life.

Define monomer.

A small molecule that can join with others to form polymers/macromolecules.

Define macromolecule.

A large molecule made up of many monomers (e.g., proteins, nucleic acids, polysaccharides).

Define high-energy compound.

A molecule like ATP that stores and transfers energy in cells.

Define organelles.

Specialized structures within a cell that perform distinct functions.

Define cytoplasm.

The contents of the cell between the plasma membrane and nucleus; includes cytosol and organelles.

Define cytosol. Which common ion is high in concentration?

The fluid portion of the cytoplasm; high [K+] inside the cell.

Define plasma membrane.

A selectively permeable lipid bilayer that separates intracellular fluid (ICF) from extracellular fluid (ECF).

Define differentiation.

The process by which cells develop specialized structures and functions.

Define cell cycle.

The series of events in a cell’s life, including division and normal physiological functions.

Define neoplasm/tumour.

An abnormal mass of cells resulting from uncontrolled cell division.

Define cancer.

A malignant neoplasm caused by mutations that allow uncontrolled growth and spread.

Define osmosis.

Movement of water across a selectively permeable membrane to equalize osmolarity.

Define tonicity.

The ability of a solution to affect cell volume by osmosis.

What kind of mutations lead to tumours and cancers?

Mutations in cell cycle regulatory genes can cause uncontrolled cell division → tumour. Further mutations can make the tumour malignant, resulting in cancer.

Distinguish between a tumour and a cancer.

A tumour is an abnormal growth due to unregulated division; cancer is a malignant tumour capable of invasion and metastasis.

What is free diffusion?

Movement of small, nonpolar molecules across the membrane without proteins or energy, down their concentration gradient.

What is facilitated diffusion?

Passive movement across membranes with the help of a protein channel or carrier.

What is passive transport?

Movement of molecules down their concentration or electrochemical gradients without energy input.

What is active transport?

Movement of molecules against concentration gradients using energy.

What is primary active transport?

Transport directly powered by ATP hydrolysis (e.g., Na⁺/K⁺ pump).

What is secondary active transport?

Transport powered by a gradient created by primary active transport (e.g., Na⁺ gradient moving glucose).

What is vesicular transport?

Specialized active transport using vesicles to move large molecules or bulk material.

A diagram shows sodium being pumped out of a cell using ATP. What type of transport is this?

Primary active transport.

A diagram shows glucose entering a cell along with sodium ions, using a sodium gradient. What type of transport is this?

Secondary active transport.

A diagram shows oxygen moving directly across the lipid bilayer. What type of transport is this?

Free diffusion (passive).

A diagram shows water moving across a membrane through aquaporins. What process is this?

Osmosis (facilitated diffusion of water).

What is a colloid in biology, and what’s an example in cells?

A mixture where large molecules remain suspended without settling; the cytoplasm is a colloid.

How much time do cells spend in interphase?

Most of their time; interphase is when they perform normal physiological functions instead of dividing.

What are integral membrane proteins, and what is their importance?

Proteins embedded in the lipid bilayer that perform diverse functions such as transport, signaling, and structural support.

Give examples of vesicular transport.

Endocytosis (bringing material into the cell) and exocytosis (releasing material out of the cell).

Why is the resting transmembrane potential negative?

Because more positive ions (Na⁺) are pumped out than K⁺ ions pumped in, and the membrane is more permeable to K⁺, leaving the inside slightly negative relative to the outside.

What are the two critical consequences of selective permeability of the plasma membrane?

Osmosis (movement of water to balance osmolarity) and the transmembrane potential (electrical difference across the membrane

What makes a mechanistic physiological explanation more complete?

It must include: stimulus, sensor, signal/integrator, effector, and outcome.

Differentiate cellular differentiation vs polarization.

Differentiation = different cell types from gene expression. Polarization = asymmetry within one cell (apical/basal regions).

Define cell, tissue, organ.

Cell = basic unit; Tissue = group of similar cells + ECM; Organ = ≥2 tissues performing a function.

Differentiate tissue membrane vs fascia.

Membrane = epithelium + connective tissue.

Fascia = connective tissue only, supporting/separating organs.

Differentiate clot vs scar.

Clot = short-term fibrin/platelet plug; Scar = long-term collagen network replacing damaged tissue.

Name the 4 tissue types and give examples.

Epithelial (skin, gut lining), Connective (blood, bone, cartilage, adipose), Muscle (skeletal, cardiac, smooth), Nervous (brain, spinal cord).

What is this?

Muscle tissue

What is this?

Nervous tissue

What is this?

Epithelial tissue

What is this?

Connective Tissue

Why must all 4 tissue types be present in most organs?

To integrate protection, structure, movement, and signaling. Removing one disrupts organ function.

What are shared features of epithelial tissue?

Polarity (apical/basal), intercellular junctions, basement membrane.

Functions of epithelia?

Protection, permeability control, sensation, secretion.

What if basement membrane is lost?

Epithelium detaches, repair impaired, cancer invasion risk ↑.

What is the role of tight junction proteins?

Control paracellular transport. Leaky junctions = allow solutes/water; Tight = block transport.

How do you classify epithelial tissues?

By cell shape (squamous, cuboidal, columnar) and layers (simple, stratified, pseudostratified).

What is this?

Gland

What is this?

Mesothelium

What is this?

Cuboidal

What is being labelled?

Keratin

Wht is this?

Pseudostraified + ciliated

What is this?

stratified squamous

What is this?

Endothelium

What is this?

Transitional

Apical vs Basolateral

In contact with lumen vs in contact with ISF

What’s the functional advantage of stratified squamous epithelium?

Multiple layers resist mechanical/chemical stress (skin, mouth).

Why is simple squamous ideal for alveoli?

Thin layer allows rapid gas diffusion.

Histological definition of connective tissue?

Cells scattered in ECM with fibers + ground substance.

Why is blood connective tissue?

Cells (RBCs, WBCs, platelets) suspended in plasma (liquid ECM).

Functions of connective tissue?

Framework, transport, protection, interconnection, energy storage, defense.

Compare loose vs dense connective tissue.

Loose = fewer fibers, more cell types, flexible (areolar, adipose, reticular).

Dense = more fibers, fewer cells, strong (tendons, ligaments).

Key fiber types in connective tissue?

Collagen = tensile strength; Elastin = recoil/stretch.

Why do tendons heal poorly?

Dense CT has fewer cells and poor blood supply → slow repair.

What if collagen is defective?

Fragile tissues → skin tears, vessel rupture (e.g., Ehlers-Danlos syndrome).

How does epithelial repair differ from connective repair?

Epithelium = rapid cell proliferation. Connective = collagen deposition by fibroblasts → scar.

Steps of CT repair after injury?

Clot formation → fibroblasts secrete collagen → scar forms.

Why do old wounds reopen with vitamin C deficiency?

Collagen synthesis impaired → weak scar tissue.

Why do wounds bleed more after knocking off a scab?

Fragile new capillaries in granulation tissue rupture.

Why is muscle tissue considered specialized?

It uniquely contracts to produce force.

Why is nervous tissue considered specialized?

Sends/receives electrochemical signals for rapid communication.

What happens if fibrocytes fail to maintain ECM proteins?

Tissue weakens over time → impaired function and healing.

Why do connective tissues differ in healing ability?

Blood supply & cell density vary (loose heals faster than cartilage or tendon).

What is the key specialization of muscle tissue?

Muscle cells (myocytes) are specialized to contract and generate force.

What is this and what are the arrows pointing at?

connective tissue proper, black = elastin, organge = collagen

What is the function of nervous tissue?

Send and receive information via electrochemical signals.

Is cartilage a connective tissue? Why?

Yes — cells (chondrocytes) in ECM with collagen/ground substance.

How do epithelial tissues repair?

Rapid proliferation of basal stem cells.

Can all tissues repair after injury?

No. Epithelium heals well, connective varies, muscle limited (except smooth), nervous tissue very limited.

Predict the consequence of impaired fibroblast activity during repair.

Reduced collagen deposition → fragile scar, poor wound healing

What is this?

Thin skin

what is this?

thick skin

True/False: Children’s skin is stretchier than adults. Explain.

True. Children have more elastic fibers and hydration; aging reduces elastin → skin stiffens.

True/False: Baby oil makes tanning safer.

False. It enhances UV penetration → more DNA damage.

True/False: You can exfoliate a scar away.

False. Scars form in dermis; exfoliation removes only epidermis.

Define integument.

The skin (cutaneous membrane) + accessory structures (hair, nails, glands).