L10 Nerve Conduction

What two adaptations of an egg cell are important for its function?

The egg cell has a large cytoplasm for nourishment and a tough outer membrane to prevent multiple fertilizations.

Why do root hair cells have many mitochondria?

Root hair cells have many mitochondria to provide energy for active transport of ions and nutrients from the soil.

What two types of tissue/fibres are found in the walls of arteries and veins?

The walls of arteries and veins are made up of elastic tissue and collagen.

What is 88mm in µm?

88mm is equivalent to 88,000 micrometers (µm).

Why is it important for alveolar epithelial tissue to be thin?

It is important for alveolar epithelial tissue to be thin to facilitate efficient gas exchange.

What is the role of sensory neurones?

Sensory neurones allow us to feel a stimulus.

What distinguishes myelinated from non-myelinated neurones?

Myelinated neurones have a myelin sheath which speeds up nerve impulse transmission, while non-myelinated neurones do not.

What occurs at the nodes of Ranvier during nerve impulse conduction?

Action potentials are generated at the nodes of Ranvier, allowing impulses to jump along the axon in a process called saltatory conduction.

What creates the resting potential of a neurone?

The sodium-potassium pump pumps 3 sodium ions out of the neurone and 2 potassium ions into the neurone, creating a resting potential of -70mV.

What happens when a neurone is depolarised?

When a neurone is depolarised, its charge reaches +40mV, indicating an action potential has occurred.

What is the role of neurotransmitters in nerve impulse transmission?

Neurotransmitters carry the impulse from one neurone to another by binding to receptors and altering the charge inside the neurone.

What does the term 'all or nothing response' refer to in neurones?

The all or nothing response refers to the neurone either firing an action potential completely or not at all, without partial responses.

How does the myelin sheath contribute to faster nerve impulse propagation?

The myelin sheath insulates the axon, allowing action potentials to jump between nodes, which speeds up conduction.

What is an ECG and what does it measure?

An ECG (electrocardiogram) measures the electrical changes in the heart as a wave of depolarisation spreads across it.

What do the letters P, QRS, and T represent in an ECG?

P represents atrial depolarisation, QRS complex indicates ventricular depolarisation, and T represents ventricular repolarisation.

What causes the hyperpolarization of a neurone?

Hyperpolarization occurs when K+ channels are slow to close, causing K+ ions to diffuse out of the neurone, resulting in a membrane potential of -90mV.