Nervous coordination and muscles

Question 1

Can you distinguish between nervous and hormonal coordination?

Answer 1

Nervous coordination is fast, hormones are slow

Nervous responses tend to be muscle contractions and other temporary responses, hormones are often involved in long-term processes like growth

Question 2

Can you describe the different types of neurone?

Answer 2

sensory neron, motor neron, and interneuron

Question 3

Can you describe the nature of resting potential?

Answer 3

This occurs as a result of an inbalance between sodium ions and potassium ions

Question 4

Can you explain how resting potentia is established in a neurone?

Answer 4

The membrane contains many sodium-potassium pumps. Sodium-potassium pumps use active transport to pump three sodium ions (Naᐩ) out of the neurone, and two potassium ions (Kᐩ) in. The membrane is not permeable to sodium ions, so they cannot diffuse back in, creating a sodium ion electrochemical gradient

Potassium ion channels make the membrane permeable to potassium ions. The channels allow Kᐩions to diffuse back out of the neurone, so they move from an area of high concentration (the cytoplasm) to an area of low concentration (extracellular space), increasing the positive charge outside.

Anion concentrations are higher inside the neurone. Anions are large molecules with a negative charge, therefore increasing theelectrochemical gradientof the membrane.

Question 5

Can you explain what an action potential ?

Answer 5

A rapid sequence of change in the voltage across a membrane

Question 6

Can you explain how an action potential passes along an unmyelinated axon ?

Answer 6

In unmyelinated axons, depolarization of the cell membrane must spread to the immediately adjacent region of the membrane, raising the potential passively until reaching the threshold voltage. Thus, the action potential propagates as a continuous wave of depolarization

Question 7

Can you explain how an action potential passes along a myelinated axon ?

Answer 7

Myelin insulates the axon to prevent leakage of the current as it travels down the axon.Nodes of Ranvier are gaps in the myelin along the axons; they contain sodium and potassium ion channels, allowing the action potential to travel quickly down the axon by jumping from one node to the next.

Question 8

Can you describe the factors that affect the speed of conductance of an action potential

Answer 8

1. presence or absence of myelin sheath- if an axon is mylinated then conduction is much faster
2. diameter of the axon- the grater the diameter the faster the conduction
3. temperature- high temperature means that ions can diffuse more rapidly

Question 9

Can you explain what is meant by the refractory period ?

Answer 9

After the sodium ion channels have been activated, they cannot re-open until resting potential has been established

Question 10

Can you explain the role of the refractory period in spearating one impulse the next ?

Answer 10

The refractory period enables a time delay between action potential, this also encourages unidirectional flow of action potentials because they cannot travel backwards to inactive neuron

Question 11

Can you explain the meaning of the all or nothing principle

Answer 11

Means that signal transmission between neurons is not dependent on the strength of the stimuli but rather only that the initial threshold is met

Question 12

Can you describe the structure of a synapse ?

Answer 12

. A synapse is made up of a presynaptic and postsynaptic terminal.

The presynaptic terminal is at the end of an axon and is the place where the electrical signal (the action potential) is converted into a chemical signal (neurotransmitter release). The postsynaptic terminal membrane is less than 50 nanometers away and contains specialized receptors. The neurotransmitter rapidly (in microseconds) diffuses across the synaptic cleft and binds to specific receptors.

Question 13

Can you describe the function that synapses perform ?

Answer 13

Transmitting information between neurons by allowing the electrical impulse from the presynaptic neuron to be transmitted to the postsynaptic neuron through the release of neurotransmitters

Question 14

Can you explain how information is transmitted across a synapse ?

Answer 14

By allowing the electrical impulse from the presynaptic neuron to be transmitted to the postsynaptic neuron through the release of neurotransmitters

Question 15

Can you describe the gross and microscopic of a skeletal muscle ?

Answer 15

booklet that greenberg

Question 16

Can you describe the untrastructure of a myofibril ?

Answer 16

The myofibrils aremade up of thick and thin myofilaments, which give the muscle its striped appearance. The thick filaments are composed strands of the protein myosin, and the thin filaments are strands of the protein actin

Question 17

Can you explain how actin and myosin are arranged within a myofibril ?

Answer 17

In skeletal muscle, the arrangement of actin and myosin isvery ordered into structures called sarcomeres. In a sarcomere, certain microfilaments of actin line up in rows, where myosin heads form thicker fibrils that bind to these fibrils and crosslink

Question 18

Can you explain what is meant by antagonistic muscles and how they operate ?

Answer 18

In an antagonistic muscle pairas one muscle contracts the other muscle relaxes or lengthens. The muscle that is contracting is called the agonist and the muscle that is relaxing or lengthening is called the antagonist.

Question 19

Can you summarise the evidence that supports the sliding filament mechanism of muscle contraction ?

Answer 19

The sliding filament theory explains the process of muscle contraction during which the thin filaments slide over the thick filaments, which shortens the myofibril

Question 20

Can you explain how the sliding filament mechanism causes a muscle to contract and relax ?

Answer 20

a muscle fiber contracts when myosin filaments pull actin filaments closer together and thus shorten sarcomeres within a fiber.

When all the sarcomeres in a muscle fiber shorten, the fiber contracts.

Question 21

Can you state where the energy for muscle contraction comes from ?

Answer 21

The energy is derived fromadenosine triphosphate (ATP) present in muscles