Physiology Summery - FILE 273 PAGES

500 English vocabulary-style flashcards covering comprehensive human physiology based on specific lecture notes.

Compartmentalisation

The process where cell membranes act as barriers allowing materials to be collected inside or excluded from cells.

Simple diffusion

Movement of substances from high to low concentration until equilibrium is established, without energy.

Facilitated diffusion

Carrier proteins moving substances down a concentration gradient without energy use, showing specificity and saturation.

Protein mediated transport

Active or passive transport occurring through channel proteins or carrier proteins in the membrane.

Channel proteins

Proteins forming water-filled pores in membranes that can be gated by membrane potential or ligand binding.

Carrier proteins

Highly selective proteins that bind molecules and change conformation to transport substances.

Uniport

A carrier-mediated transport that moves one substance in one direction.

Symport

Co-transport where molecules are carried in the same direction.

Antiport

A transport mechanism where molecules are carried in opposite directions.

Osmosis

The diffusion of water across a semipermeable membrane caused by concentration differences.

Tonicity

The ability of solutes to generate a driving force for the movement of water molecules.

Isotonic

A solution with equal osmotic pressure to a cell.

Hypertonic

A solution with higher osmotic pressure than the cell.

Hypotonic

A solution with lower osmotic pressure than the cell.

Active transport

The pumping of substances against a concentration gradient by transmembrane proteins using energy (ATP).

Primary active transport

Transport that establishes a concentration gradient, such as the $\text{Na}^+/\text{K}^+$ pump.

Secondary active transport

Indirect ATP use using potential energy stored in a concentration gradient (e.g., sodium/glucose transport).

Endocytosis

The formation of a vesicle to bring a substance inside a cell.

Pinocytosis

Non-selective endocytosis for fluids and dissolved substances.

Phagocytosis

Process where a cell enfolds a particle in a vesicle via pseudopod formation.

Exocytosis

Transport out of cells using vesicles that fuse with the membrane, requiring ATP and Calcium.

Transcytosis

Material passing through cells using endocytosis, vesicular transport, and exocytosis without contacting the cytoplasm.

Diffusion potential

Potential caused by an ion concentration difference on two sides of a membrane.

Nernst Potential

The diffusion potential level across a membrane that exactly opposes net diffusion of a particular ion.

EMF (Electromotive force) equation at $37\,^{\circ}C$

$\text{EMF (mmV)} = \pm 61 \times \log(\frac{C_{\text{inside}}}{C_{\text{outside}}})$.

Resting Membrane Potential of large nerves

A value of $-70\,mmV$, meaning the inside is more negative than the extracellular fluid.

Sodium-Potassium Pump

An electrogenic pump transporting $3\,\text{Na}^+$ outside and $2\,\text{K}^+$ inside to create negativity.

Potassium Nernst Potential

The calculated potential for the $35:1$ ratio of potassium across a nerve membrane, reaching $-94\,mmV$.

Sodium Nernst Potential

The calculated potential for the sodium ratio across a nerve membrane, reaching $+61\,mmV$.

Nerve Action Potentials

Rapid changes in membrane potential spread rapidly along the nerve fibre membrane.

Depolarisation stage

Stage where the membrane becomes permeable to sodium, allowing it to neutralize the $-70\,mmV$ resting potential.

Repolarisation stage

Stage where sodium channels close and potassium channels open, re-establishing the negative resting potential.

Hyperpolarisation

A state where the potential is briefly more negative than the resting potential due to slow K+ channel closure.

Na+ Activation gate

A gate near the outside of the channel that opens when potential reaches $-50$ to $-40\,mmV$.

Na+ Inactivation gate

A gate near the inside of the channel that closes shortly after the activation gate opens.

Slow channels

Voltage-gated calcium channels that are about $20$ times slower than sodium channels.

Saltatory conduction

The jumping of action potentials from one Node of Ranvier to the next along myelinated nerves.

Nodes of Ranvier

Unmyelinated gaps ($1\text{-}3\,mm$ apart) where the membrane must be depolarised for saltatory conduction.

Absolute refractory period

Period where no new action potential can be induced because Na+ and Ca channels are inactivated.

CNS compositions

The brain and the spinal cord, containing more than $100\,billion$ neurons.

Nervous System Effectors

Structures such as muscles and glands that perform actions dedicated by the nervous system.

Soma

The main cell body of the neuron.

Axon

A single extension from the soma that carries the neuronal output.

Dendrites

Branches of the soma extending up to $1\,mm$ to receive incoming synaptic connections.

Presynaptic terminals (Synaptic knobs)

$10\text{,}000$ to $20\text{,}000$ knobs on dendrites/soma of motor neurons where transmitters are released.

Chemical synapses

Synapses where a neurotransmitter is secreted to act on receptor proteins of the next neuron.

Electrical synapses

Synapses characterized by direct open fluid channels (gap junctions) that conduct electricity cell-to-cell.

One-way conduction

A principle of chemical synapses where signals are transmitted only from presynaptic to postsynaptic neurons.

Releasing site

Specific proteins on the inside surface of the presynaptic membrane where calcium binds to release vesicles.

G-Proteins

Receptor-attached elements used for elongated changes in postsynaptic neuronal excitation.

Acetlycholine (transmitter class)

Class 1 synaptic transmitter.

Amines (transmitter class)

Class 2 synaptic transmitters including Norepinephrine, Epinephrine, Dopamine, Serotonin, and Histamine.

Amino Acids (transmitter class)

Class 3 synaptic transmitters including GABA, Glycine, Glutamate, and Aspartate.

Nitric oxide (transmitter class)

Class 4 synaptic transmitter.

EPSP

Excitatory postsynaptic potential; the positive increase in voltage above normal resting neuronal potential.

IPSP

Inhibitory postsynaptic potential; increased negativity beyond resting potential via Cl- influx and K+ outflow.

Axon hillock

The site where the action potential is induced if the postsynaptic potential exceeds the threshold.

Neuroglia (Glia)

Non-neuronal cells that maintain homeostasis, form myelin, and provide support for neurons.

CNS Glial cells

Oligodendrocytes, astrocytes, ependymal cells, and microglia.

PNS Glial cells

Schwann cells and satellite cells.

Spatial summation

Summation resulting from the simultaneous stimulation of multiple presynaptic terminals spread over the neuron.

Temporal summation

Summation resulting from successive discharges from a single presynaptic terminal.

Facilitated neuron

A neuron whose membrane potential is closer to firing than normal due to summated potentials that did not reach threshold.

Fatigue of synaptic transmission

Mechanism where the firing rate decreases after repetitive rapid stimulation, preventing over-excitability.

Alkalosis effect (CNS)

Greatly increases neuronal activity and excitability, potentially leading to epileptic seizures.

Acidosis effect (CNS)

Depresses neural activity and can cause a coma-like state.

Hypoxia effect (CNS)

Cessation of oxygen leads to non-excitability and neuronal death within minutes.

Caffeine effect (CNS)

Increases neuronal excitability by reducing the threshold for excitation.

Strychnine

Drug that increases excitability by blocking inhibitors like glycine, potentially causing muscle spasms.

Convergence

A single neuron receiving impulses from two or more fibres for the summation of signals.

Divergence

Impulses leaving a neuron passing into several output fibres to amplify the impulse.

Reverberating circuit

Trains of impulses traveling in predisposed circuits of neurons, potentially causing memory.

Lateral inhibition

Higher order higher order neuronal action (surround inhibition) to avoid lateral spread of transmission.

Reflex action

An involuntary and nearly instantaneous movement in response to a stimulus.

Reflex arc

The neural pathway that controls a reflex, involving sensory neurons, an integrating center, and motor neurons.

Stretch reflex

Contraction of a muscle in response to its lengthwise stretch (e.g., biceps reflex C5, C6).

Patellar reflex roots

$L2$, $L3$, and $L4$.

Ankle jerk reflex roots

$S1$ and $S2$.

Golgi tendon reflex

The inverse of a stretch reflex; contraction in response to striking a tendon.

Monosynaptic reflex

A reflex involving only one sensory neuron and one motor neuron with a single chemical synapse.

Polysynaptic reflex

A reflex involving one or more interneurons connecting afferent (sensory) and efferent (motor) signals.

Withdrawal reflex

A nociceptive reflex intended to protect the body from damaging stimuli via reciprocal innervation.

Reciprocal innervation

Nerve impulses that contract flexors while motor neurons sends inhibitory impulses to extensors during a withdrawal reflex.

Sympathetic Nervous System (SNS) origin

Segments T1 to L2 of the spinal cord.

Parasympathetic Nervous System (PNS) source

Cranial nerves III, VII, IX, X and the lowest spinal cord part (S2-4).

Vagus nerve (PNS content)

Contains about $75\%$ of the parasympathetic nervous system fibers.

Ramus alba

The white ramus through which preganglionic sympathetic fibers pass into the sympathetic chain.

Muscarinic receptors

Cholinergic receptors found on all effector cells stimulated by postganglionic cholinergic neurons.

Nicotinic receptors

Cholinergic receptors found on autonomic ganglia and neuromuscular junctions.

Alpha and Beta receptors

The two main types of adrenergic receptors; alpha divides into a1/a2, beta into b1/b2/b3.

Sympathetic tone

The basal rate of activity that allows the SNS to maintain a level of vascular constriction.

Adrenal Medulla Output

Secretes $80\%$ Epinephrine and $20\%$ Norepinephrine.

PNS Eye effects

Contracts ciliary muscles for focusing and pupillary diameter reduction (concentric pupil).

SNS Eye effects

Controls meridional fibers to dilate the pupil.

Fight and Flight response

Massive sympathetic discharge enabling the body to perform great muscle activity under stress.

Contractility

The ability of muscle to shorten in length.

Sarcomere

The functional and contractile unit of the muscle fibre, the area between two Z-lines.

I bands

Isotropic light bands containing only thin (Actin) filaments.

A bands

Anisotropic dark bands containing thick (Myosin) and thin filaments.

H-Zone

The portion of the A band containing only thick filaments.