Nerves, Muscles & Receptors

Question 1

What is muscle made up of?

Answer 1

Muscle fibre cells

Question 2

Skeletal/striated muscle

Answer 2

This is attached to the skeleton and is used for control of voluntary movements of the body (e.g. walking etc.).

Question 3

Cardiac muscle

Answer 3

This is the heart muscle and is very strong. It looks like striated muscle but is of course under reflex autonomic control and is therefore classified as autonomic muscle.

Question 4

Smooth muscle

Answer 4

This is present throughout the body and is the type of autonomic (involuntary) muscle controlling the gut, uterus, eye, blood vessels, etc. (e.g. causes the food to pass through the gut or gastrointestinal tract).

Question 5

What is the cell?

Answer 5

Basic unit of the body. Consists of an outer cell membrane (made up of phospholipids partially coated with protein) filled inside with the cytoplasm.

Question 6

What is inside the cell?

Answer 6

• Nucleus which contains chromosomes
• Mitochondria which produce energy
• Endoplasmic reticulum which synthesises proteins and binds calcium

Question 7

What is the Nervous System made up of?

Answer 7

Consists of the Central Nervous System (CNS) comprising the brain and the spinal cord, and the Peripheral Nervous System (PNS)

Question 8

What is the PNS made up of?

Answer 8

The PNS consists of afferent (sensory) nerves which conduct impulses back to the CNS, and the efferent (motor nerves) which relay impulses from the CNS out to the body

Question 9

How is the PNS separated?

Answer 9

Split into two systems, namely the somatic and the autonomic. The somatic efferent nerves act on skeletal muscle, whereas the autonomic nerves act on cardiac muscle, smooth muscle, and glands (e.g. tear and salivary)

Question 10

What is the Autonomic Efferent System (ANS) made up of?

Answer 10

ANS consists of two parts, the parasympathetic and the sympathetic. These two systems tend to have opposite actions on the tissues they control

Question 11

What do Somatic nerves control?

Answer 11

Somatic nerves control voluntary actions (including breathing)

Question 12

What do Autonomic nerves control?

Answer 12

Autonomic nerves control involuntary actions

Question 13

Label this diagram:

Answer 13

Question 14

What is the junction/synapse between two nerves called?

Answer 14

The Ganglion

Question 15

Define ganglion

Answer 15

Junction/synapse between two nerves

Question 16

What is the junction between a nerve and a gland or muscle called?

Answer 16

The Neuroeffector Junction

Question 17

Define Neuroeffector Junction

Answer 17

The junction between a nerve and a muscle or gland.

Question 18

What is the gap between the nerve and it’s target called?

Answer 18

The Synapse

Question 19

Define synapse

Answer 19

The gap between the nerve and the target.

Question 20

How is signal transimitted?

Answer 20

Transmission of signal involves an electrical impulse down the nerve causing the release of a chemical at the nerve ending.

Question 21

Which chemical transmitted acts across the synapse in the case of the somatic system?

Answer 21

Acetylcholine

Question 22

Where is ACh also involved?

Answer 22

This neurotransmitted is also involved in all PNS operations EXCEPT in the post-ganglionic sympathetic adrenergic nerves which release noradrenaline

Question 23

How do chemical transmitters combine?

Answer 23

They combine reversibly with specific receptors on the target tissue, which can be another nerve, a muscle or a gland. This combination of transmitted with its receptor initiates the subsequent response

Question 24

What does the autonomic nervous system control?

Answer 24

Controls smooth muscle (visceral and vascular), exocrine (and some endocrine) secretions, rate and force of the heart, and certain metabolic processes (e.g. glucose utilisation)

Question 25

Describe the actions of the sympathetic and parasympathetic systems

Answer 25

Sympathetic and parasympathetic systems have opposing actions in some situations (e.g. control of heart rate, gastrointestinal smooth muscle), but not in others (e.g. salivary glands, ciliary muscle)

Question 26

When are the sympathetic and parasympathetic systems active?

Answer 26

Sympathetic activity increases in stress (‘fight or flight’ response). Parasympathetic activity predominates during ‘satiation and repose’. Both exert a continuous physiological control of specific organ under normal conditions, when the body is at neither extreme.

Question 27

What are the two main types of ACh receptor?

Answer 27

Nicotinic (one subtype found at the skeletal, somatic muscle and another subtype at autonomic ganglia) and Muscarinic (found on smooth muscle, cardiac muscle and glands)

Question 28

Which receptor does Noradrenaline act on?

Answer 28

Adrenoceptors (of which there are also several subtypes)

Question 29

What is an Agonist?

Answer 29

A drug that can be administered to the body/ or tissue to combine with receptors and produce a response. They have a direct activating action on the system.

Question 30

What is an Antagonist?

Answer 30

A drug which binds to the receptor but does not produce a response. Furthermore, they “cover up” the agonist binding site on receptors such that an agonist drug is prevented from exerting its effect.

Question 31

What are the four targets for drug action?

Answer 31

• Receptors
• Ion Channels
• Enzymes
• Carrier Molecules