PCB3703C Lab Exam 1

What is anatomy?

The study of the structure and description of the human body.

What is physiology?

The study of normal biological functions and processes of the human body (how the body works under normal conditions).

What is pathophysiology?

The study of abnormal biochemical and physical processes that occur in disease. It helps diagnose and treat conditions.

What is homeostasis?

The body’s ability to maintain a stable internal environment despite changes outside the body.

How do body systems maintain homeostasis?

All organs and systems work together in an organized and cooperative way.

What are the 4 vital signs?

• Body temperature

• Heart rate

• Respiratory rate

• Blood pressure

What is normal body temperature?

98.6°F

What is the purpose of feedback control mechanisms?

To detect changes and return the body back to homeostasis.

What does afferent mean?

Arriving (information going TO the brain).

What does efferent mean?

Exiting (information leaving the brain).

What is a negative feedback system?

A system where the response opposes or reverses the original stimulus to restore homeostasis.

What is the garden hose example of negative feedback?

If water volume is low, pressure is low. Putting your thumb over the hose increases pressure.

What is a positive feedback system?

A system where the response increases or amplifies the original stimulus.

What happens in positive feedback?

The response makes the stimulus stronger and continues until the stimulus is removed.

How does positive feedback stop?

By removing the initial stimulus.
Example: After birth, stretch and pressure stop.

What is the function of the plasma membrane?

It serves as the external barrier of the cell.

What does selectively permeable mean?

Some substances can enter and leave the cell, and some cannot.

What makes up the plasma membrane?

A phospholipid bilayer.

What does amphipathic mean?

Having both hydrophilic (water-loving) and hydrophobic (water-fearing) regions.

How are phospholipids arranged in the membrane?

• Heads face outward toward water (cytoplasm & extracellular fluid)

• Tails face inward away from water

Why can fat molecules pass through easily?

The membrane is mostly hydrophobic (lipophilic).

Can oxygen pass through the membrane?

yes because it is small and nonpolar

Can water pass through the membrane?

Yes, because it is small, but it moves slowly unless protein channels help it.

Can glucose cross freely?

No. It is too large and needs a protein to help it.

What types of molecules need assistance to cross?

Large molecules and charged molecules (ions).

What is passive transport?

Movement from high concentration to low concentration (down the gradient).

Does passive transport require energy?

no

What is simple diffusion?

Unassisted movement from high to low concentration (no protein needed).

What is facilitated diffusion?

Movement down the concentration gradient with help from a protein.

What is channel-mediated transport?

Protein channels form tunnels for small polar molecules and ions.

What is carrier-mediated transport?

A protein carries large polar molecules across the membrane.

Which is faster: channel-mediated or carrier-mediated?

Channel-mediated (because the tunnel is always open).

What is active transport?

Movement from low concentration to high concentration (against the gradient).

Does active transport require energy?

Yes

What is primary active transport?

Carrier proteins use ATP directly to pump molecules against the gradient.

What is secondary active transport?

Uses the energy from one molecule moving down its gradient to move another molecule up its gradient.

Where does the energy for secondary active transport come from?

The sodium ion gradient created by ATP.

What is vesicular transport?

Bulk movement of substances into or out of the cell using vesicles.

What is endocytosis?

Bringing substances into the cell by changing the membrane structure.

What is phagocytosis?

“Cell eating” — engulfing large solid particles into a phagosome.

Which cells perform phagocytosis?

White blood cells (to destroy bacteria).

What is pinocytosis?

“Cell drinking” — taking in extracellular fluid and dissolved substances.

What is exocytosis?

Releasing substances from the cell into the extracellular space.

What is exocytosis responsible for?

Most secretion processes.

What is osmosis?

The passive diffusion of water across a semipermeable membrane to balance solute concentrations.

Does osmosis require energy?

No, it does not use cellular energy.

In osmosis, water moves from where to where?

From lower solute concentration to higher solute concentration.

What gradient does water follow during osmosis?

Water moves along its own concentration gradient (toward more solute).

What is the goal of osmosis?

To make both sides isotonic (balanced).

What is the universal solvent in the human body?

water

What determines tonicity?

The concentration gradient of solutes.

What is tonicity?

A comparison of solute concentrations between two solutions separated by a membrane.

What is a solute?

A substance dissolved in water.

What does hypertonic mean?

Higher solute concentration compared to another solution.

What does hypotonic mean?

Lower solute concentration compared to another solution.

What does isotonic mean?

Equal solute concentrations on both sides.

What is the body’s relative goal regarding tonicity?

to be isotonic

What is osmotic pressure?

The pressure created by solutes that cannot cross the membrane.

Which solutes influence osmotic pressure?

Only non-penetrating solutes (ones that cannot cross the membrane).

Why do large molecules create high osmotic pressure?

Because they cannot cross the membrane, so water moves toward them.

What happens in an isotonic solution?

No net movement of water. Water moves equally in both directions.

What happens to cells in a hypertonic solution?

Water leaves the cell → cell shrivels (crenation).

What happens to cells in a hypotonic solution?

Water enters the cell → cell swells and may burst (lysis).

If the outside of a cell is hypertonic, which way does water move?

Out of the cell.

If the outside of a cell is hypotonic, which way does water move?

Into the cell.

What are the three types of muscle?

Smooth, Skeletal, and Cardiac.

Where is smooth muscle located?

In most hollow organs and the digestive tract.

Does smooth muscle have striations?

No, it looks smooth (no striations).

How many nuclei does smooth muscle have?

One (uninucleated).

Is smooth muscle voluntary or involuntary?

Involuntary.

Where is the nucleus located in smooth muscle?

in the center of the cell

What is the function of skeletal muscle?

It attaches to bones and allows movement.

Does skeletal muscle have striations?

yes

How many nuclei does skeletal muscle have?

Many (multinucleated).

Where are the nuclei located in skeletal muscle?

around the edges of the muscle fibers

Is skeletal muscle voluntary or involuntary?

Mainly voluntary (but some reflexes are involuntary).

Where is cardiac muscle located?

in the heart

Does cardiac muscle have striations?

yes

Is cardiac muscle uni- or multinucleated?

It can be either one or two nuclei.

Is cardiac muscle voluntary or involuntary?

involuntary

How do skeletal muscles attach to bones?

by tendons

What is the epimysium?

Connective tissue that surrounds the entire muscle.

What is the perimysium?

Connective tissue that surrounds a fascicle (bundle of muscle fibers).

What is the endomysium?

Connective tissue that surrounds each individual muscle fiber (cell).

What gives skeletal muscle its striated (striped) appearance?

The arrangement of actin and myosin myofilaments.

A muscle fiber is the same as what?

a muscle cell

What is inside a muscle fiber?

myofibrils

What is inside a myofibril?

Myofilaments (actin and myosin).

What are the two main myofilaments?

• Thick filaments = Myosin

• Thin filaments = Actin

What is a sarcomere?

The repeating functional unit of a myofibril

A sarcomere extends from where to where?

Z-line to Z-line.

What is the M line?

The middle of the sarcomere (contains myomesin protein).

What is the A band?

Dark region containing all of myosin and overlapping actin.

What is the I band?

Light region containing only actin.

What is the H zone?

The center of the A band containing only myosin (no actin overlap).

Do actin and myosin change length during contraction?

No. They slide and increase overlap.

What happens to sarcomeres during contraction?

They shorten as actin and myosin overlap more.

What two proteins are located on actin?

Troponin and tropomyosin.

What is the role of troponin and tropomyosin?

They regulate muscle contraction.

What are the connective tissue layers (outer to inner)?

Epimysium → Perimysium → Endomysium.