Exam 1 Review: Human Physiology

Flashcards covering key concepts from Exam 1 Review, including cell physiology, membrane transport, cardiac dynamics, and system regulation.

According to the lecture, what percentage of the cell is composed of water?

$$70-85\%$$

What is the primary function of water within the cell?

It allows diffusion and metabolic reactions to occur.

What percentage of the cell composition is typically made up of proteins?

$$10-20\%$$

Which cellular components control nearly all cellular functions as structural proteins and enzymes?

Proteins

What is the approximate percentage of lipids in a cell?

$$2\%$$

What is the main role of lipids in the cell?

They are essential for membrane formation.

What percentage of the cell is composed of carbohydrates?

$$1\%$$

In which processes are cellular carbohydrates primarily involved?

Cell recognition and energy storage.

What is the concentration of Na+ in the Extracellular Fluid (ECF)?

Approximately $142$

What is the concentration of Na+ in the Intracellular Fluid (ICF)?

Approximately $10$

What is the concentration of K+ in the Intracellular Fluid (ICF)?

Approximately $140$

What is the concentration of K+ in the Extracellular Fluid (ECF)?

Approximately $4$

What is the approximate intracellular concentration of Ca2+?

$$0.0001$$

List the membranous organelles of a eukaryotic cell as noted in the transcript.

Plasma membrane, RER, SER, Golgi apparatus, Lysosomes, Mitochondria, and Peroxisomes.

List the non-membranous organelles of a eukaryotic cell.

Microtubules, Filaments, Centrioles, Ribosomes, and Proteasomes.

What are the alternative names for the plasma membrane mentioned in the notes?

Cell membrane, plasma lemma, or bio membrane.

How is the physical nature of the plasma membrane described in the Fluid Mosaic Model?

Quasi fluid (partially fluid and partially solid), elastic, pliable, and film-like.

What is the average thickness of the plasma membrane?

$75\, \text{Å}$ (ranging from $50-100\, \text{Å}$).

In terms of permeability, how does the plasma membrane behave toward solutes vs. water?

It is selectively permeable for solutes but semi permeable for water.

What happens if a part of the membrane is injured?

It is dynamic and repaired within no time.

How does the plasma membrane appear under an electron microscope?

Trilaminar or tripartite.

What is the lipid composition range of the plasma membrane?

$$20-79\%$$

What is the protein composition range of the plasma membrane?

$$20-70\%$$

What is the carbohydrate composition range of the plasma membrane?

$$1-5\%$$

What is the percentage of water found in the plasma membrane?

$$20\%$$

Name five functions of the cell membrane according to the transcript.

Compartmentalization, protection from injury, organic connections (plasmodesmata/gap junctions), selective permeability barrier, and transporting solutes.

How does the cell membrane respond to external stimuli and exocytosis?

It responds to external stimuli and handles the throwing out of secretory/excretory products.

What structures on the outer side of the membrane form the glycocalyx?

Glycolipids and glycoproteins.

What is the definition of homeostasis provided in the notes?

An active regulatory mechanism that tends to minimize disturbances to the internal environment.

In a homeostatic feedback loop, where is the information from the receptor sent?

Along the afferent pathway to the Control Center.

In a homeostatic feedback loop, where is the information from the control center sent?

Along the efferent pathway to the Effector.

What are the two major phases of the life cycle of the cell?

Interphase and M phase (mitosis).

What percentage of the cell cycle is typically spent in Interphase?

$$>95\%$$

List the stages of Interphase in the eukaryotic cell cycle.

G1 phase, S phase, and G2 phase.

What specific process occurs during the S phase of the cell cycle?

DNA synthesis (DNA replication) and Histone synthesis.

What are the four phases of Mitosis?

Prophase, Metaphase, Anaphase, and Telophase.

What is the typical duration of the G1 phase?

$$8\, \text{h}$$

What is the typical duration of the S phase?

$$25\, \text{h}$$

How long does the G2 phase typically last?

$$2.5-3\, \text{h}$$

How long does Mitosis (M phase) typically last?

Approximately $1\, \text{h}$

What occurs during the G1 phase of the cell cycle?

Cell growth, RNA and protein synthesis, and cells recover their size.

What occurs during the G2 phase of the cell cycle?

Accumulation of proteins required for mitosis and general preparation for mitosis.

What is the G0 phase?

A quiescent state where cellular differentiation occurs and the cell cycle is suspended.

During which phase of mitosis do chromosomes condense?

Prophase

During which phase of mitosis do chromosomes line up in single file?

Metaphase

What is the result of Anaphase and Telophase?

Genetically identical daughter cells are produced.

What is the role of Messenger RNA in the Central Dogma?

It plays an independent role in protein formation.

What is passive transport and what is its energy source?

Transport in favor of the gradient that uses the energy of molecular motion/kinetic energy and does not require ATP.

List four types of passive transport.

Diffusion/Simple diffusion, Facilitated diffusion, filtration, and Osmosis.

What defines active transport?

Transport using energy from ATP against a concentration gradient.

What are the two main sub-categories of active transport mentioned?

Carrier-mediated active transport and Bulk transport.

What are the types of bulk transport?

Exocytosis and Endocytosis (Phagocytosis and Pinocytosis).

Does facilitated diffusion require ATP?

No, it is a form of passive transport, though it uses carrier proteins.

What is the difference between primary and secondary active transport regarding energy usage?

Primary uses ATP directly; secondary requires an input of energy (created by a concentration gradient from primary transport).

Name four examples of primary active transporters.

Na+-K+-ATPase, Ca2+-ATPase, H+-ATPase, and H+-K+-ATPase.

Is the Na+-K+-ATPase pump an antiport or uniport mechanism?

Antiport

Is the Ca2+-ATPase a uniport or antiport mechanism?

Uniport

How does the Na+ K+ ATPase move ions?

It pumps Na+ out of the cell and K+ into the cell.

Ion movement and the resting membrane potential are primarily determined by what gradient?

K+ concentration gradient.

What are the three types of gated channels that control ion permeability?

Mechanically gated, Chemically gated, and Voltage-gated.

At what voltage does the Na+ activation gate open and the inactivation gate close?

The gate opens during activation ($-90\, \text{to} +35\, \text{mV}$) and the inactivation gate closes at $+35\, \text{mV}$.

How does the neuron move Na+ and K+ to maintain resting potential?

Active transport moves Na+ ions outside and K+ ions inside.

What molecules in the cell help maintain a negative internal charge?

Large molecules (organic molecules).

What is meant by resting potential in excitable cells?

The membrane potential in the absence of excitation.

What is the typical resting cell membrane potential range?

$-70\, \text{mV to} -90\, \text{mV}$.

Which electrolyte is considered the most important in the body for determining resting potential?

K+

What is defined as the difference in electric potential between the interior and exterior of a cell?

Membrane potential.

In an Action Potential, what causes the cell to reach threshold?

A depolarizing stimulus.

What causes the rapid depolarization phase of an Action Potential?

Rapid Na+ entry.

What happens at the peak of the Action Potential (approx $+30\, \text{mV}$)?

Na+ channels close and slower K+ channels open.

Which ion movement causes the repolarization of the cell?

K+ moving from the cell to the extracellular fluid.

What causes hyperpolarization (the undershoot) in an Action Potential?

K+ channels remain open and additional K+ leaves the cell.

What is the absolute refractory period?

The period during an AP where another stimulus cannot trigger a second AP, regardless of strength.

How do neurons and muscle cells differ from other cells in their function?

They are excitable, conduct electric impulses by moving Na+ and K+, and allow Ca2+ to move across membranes.

What is the primary intracellular cation?

Potassium (K+)

What is the primary extracellular cation?

Sodium (Na+)

What is the primary intracellular anion?

Phosphate ($PO_4^{3-}$)

What is the primary extracellular anion?

Chloride (Cl-)

What is the resting membrane potential of a neuron vs. Skeletal Muscle (SKM)?

Neuron = $-70\, \text{mV}$, SKM = $-90\, \text{mV}$

What neurotransmitter is released at the neuromuscular junction for Skeletal Muscle?

Acetylcholine (ACh)

In Skeletal Muscle E-C coupling, how does the AP reach the interior of the muscle?

It propagates along the sarcolemma and down T-tubules.

What receptor in the T-tubules acts as a voltage sensor in skeletal muscle?

Dihydropyridine receptor (DHP) or L-type Ca2+ channel.

What receptor on the Sarcoplasmic Reticulum (SR) releases Ca2+ in skeletal muscle?

Ryanodine receptor (RyR1).

Is extracellular Ca2+ required for Skeletal Muscle contraction?

No, it is released from the SR.

To what does Ca2+ bind on the thin filament in skeletal muscle?

Troponin C

What protein moves to expose myosin-binding sites on actin?

Tropomyosin

What pump is responsible for returning Ca2+ to the SR?

SERCA (Sarcoplasmic/Endoplasmic Reticulum Ca2+-ATPase).

What theory explains the basic principles of skeletal and smooth muscle contraction?

Sliding Filament Theory.

What is the source of Ca2+ for smooth muscle contraction?

Both extracellular space (L-type channels) and SR (IP3 receptors/Ca2+-induced release).

What is the Ca2+ sensor in smooth muscle?

Calmodulin

Which enzyme phosphorylates myosin light chains to allow binding in smooth muscle?

Myosin light-chain kinase (MLCK).

What enzyme is responsible for smooth muscle relaxation?

Myosin light-chain phosphatase (MLCP).

Compare the contraction speed of skeletal muscle vs smooth muscle.

Skeletal is very fast (ms); Smooth is slower (seconds).

Which muscle type lacks T-tubules and uses caveolae instead?

Smooth Muscle

What is the 'latch state' in smooth muscle?

The ability to sustain tonic force with little energy for a prolonged period.

What allows smooth muscle cells to contract in unison?

Electrical coupling by gap junctions.

What are the bulbous endings of nerve fibers in smooth muscle called?

Varicosities

What is the formula for Cardiac Output (CO)?

$$CO = HR \times SV$$

What is the normal resting Cardiac Output?

$5\, \text{L/min}$ (range $5-6\, \text{L/min}$).

What is a negative chronotropic effect?

A decrease in heart rate.