C13 Nervous System

Question 1

Central Nervous System (CNS) consists of

Answer 1

brain and spinal cord

Question 2

Peripheral Nervous System (PNS) consists of…

Answer 2

all neurones that connect CNS to rest of body. These are the sensory neurones, carry nerve impulses from receptors to CNS, and motor neurones (which carry nerve impulses away from CNS to the effectors).

Question 3

Functional Organisation
(Somatic Nervous System)

Answer 3

under conscious control (used when you voluntary decide do something. SNC carries impulses to the body’s muscles.

Question 4

Functional Organisation
(Autonomic Nervous System)

Answer 4

works constantly. Under subconscious control and used when body does something automatically without you deciding to do it (involuntary). E,g heart beat or digest food. ANS carries nerve impulses to glands, smooth muscle and cardiac muscle.

Question 5

ANS further divided by function into…

Answer 5

Sympathetic and parasympathetic nervous system.

Question 6

Sympathetic nervous system

Answer 6

Sympathetic nervous system: if the outcome increases activity (increase HR).

Question 7

Parasympathetic nervous system:

Answer 7

Parasympathetic nervous system: if the outcome decreases activity (decrease HR or breathing after exercise).

Question 8

Mechanoreceptors

Answer 8

Detect movement, pressure and tensions, e.g sound

Question 9

Chemoreceptors

Answer 9

Detect chemical stimuli, e.g taste and smell

Question 10

Thermorecptors

Answer 10

Detect temperature change, e,g in the skin, the hypothalamus

Question 11

Electroreceptors

Answer 11

detect electrical fields (mainly found in fish)

Question 12

Photoreceptors

Answer 12

detect light and some other form of electromagnetic radiation, e.g bees detect UV light.

Question 13

Role as a Transducer

Answer 13

sensory receptors detect range different stimuli. The receptor converts the stimulus into nerve impulse, called a generator potential.

Question 14

Neurones role

Answer 14

role to transmit electrical impulses rapidly around body, so it can respond changes in its internal and external environment.

Question 15

Structure of a Neurone:
Cell body

Answer 15

contains nucleus surrounded by cytoplasm. In cytoplasm large amounts ER and mitochondria which involved production neurotransmitters (chemicals which used to pass signals from one neurone to next).

Question 16

Structure of a Neurone:
Dendron

Answer 16

short extensions, come from cell body. Extensions divided into smaller and smaller branches known dendrites, responsible transmitting electrical impulses towards cell body.

Question 17

Structure of a Neurone:
Axons

Answer 17

singular, elongated nerve fibres, transmit impulses away from cell body. Can be very long. Fibres cylindrical in shape, consisting very narrow region cytoplasm surrounded by plasma membrane.

Question 18

Skeletal Muscle

Answer 18

responsible for movement, usually attached to bone, make up bulk of body’s muscle tissue.

Question 19

Cardiac Muscle

Answer 19

found only in the heart, myogenic meaning they are self stimulating causing a continuous rhythm.

Question 20

Involuntary/Smooth Muscle:

Answer 20

found in many parts of the body such as walls of hollow organs such as bladder and stomach, and in vessels such as arteries and digestive tract.

Question 21

Skeletal muscles
-Fibre appearance
-Control
-Arrangement
-Contraction speed
-Length of contraction
-Structure

Answer 21

-Striated
-Conscious (voluntary)
-Regularly arranged so muscle contracts in one direction
-Rapid
-Short

Question 22

Cardiac muscle:
-Fibre appearance
-Control
-Arrangement
-Contraction speed
-Length of contraction
-Structure

Answer 22

-Specialised striated
-Involuntary
-Cells branch and interconnect resulting in simultaneous contraction
-Intermediate
-Intermediate
-Cardiac muscles does show striations but they are much fainter than those in skeletal muscles. Fibres are branched and uninucleated.

Question 23

Involuntary Muscles
-Fibre appearance
-Control
-Arrangement
-Contraction speed
-Length of contraction
-Structure

Answer 23

-Non-striated
-Involuntary
-No regular arrangement- different cells can contract in different directions
-Slow
-Can remain contracted for relatively long period of time
-Muscles show no cross striations are called non-striated or unstriped muscles. Fibres are spindle shaped and uninucleated.

Question 24

Types of neurones

Answer 24

sensory
motor
relay

Question 25

relay neurones

Answer 25

transmit impulses between neurones, e.g between sensory neurones and motor neurones. They have many short axons and dendrons.

Question 26

sensory neurones

Answer 26

carries nerve impulses from a sense organ to CNS. Has a long dendron and shorter axon than motor neurone.

Question 27

motor neurone

Answer 27

carries impulse from the CNS to effector muscle or glands, it’s cell body lies with the CNS.

Question 28

what are the stages of a nervous response to a stimuli?

Answer 28

Stimuli —> Receptor —> Sensory —> Relay —> Motor —> Effector —> Response

Question 29

Axons of some neurones covered in a myelin sheath (made many layers plasma membrane).
how does this come to be?

Answer 29

-Special cells, Schwann cells, produce layers by growing around axon many times, forming a double layer of phospholipid bilayer laid down each time they grow round.

Question 30

what do myelin sheaths act as, and how?

Answer 30

-Myelin sheath acts insulating layer, allows these myelinated neurones to conduct electrical impulses much faster than unmyelinated neurones.

-Between adjacent Schwann cells there’s small gap known as ‘a node of Ranvier’ (creates gaps in myelin sheath)

-In myelinated neurones,electrical impulse can jumps from one node to the next (transmitted much faster),

Question 31

how is the brain protected?

Answer 31

Brain protected by skull, and initially surrounded by protective membrane (meninges).

Question 32

Cerebrum

Answer 32

controls voluntary actions, i.e learning, memory, personality and conscious thought.

Question 33

Cerebellum

Answer 33

controls unconscious functions, i.e posture, balance, and non-voluntary movement.

Question 34

Medulla Oblongata

Answer 34

used in autonomic control, i.e controls HR and breathing rate.

Question 35

Hypothalamus

Answer 35

regulatory centre for temp and water balance.

Question 36

Pituitary Glands

Answer 36

stores and releases hormones that regulate many body functions.

Question 37

Cerebrum function

Answer 37

-​Receives information, interprets it, and then sends an impulse along motor neurons to effector organs to produce a response.
-Responsible for controlling all conscious responses and some involuntary responses.
-Many folds in the cerebrum mean there is increased surface area, and therefore increased capacity for activity.
-Each hemisphere controls the opposite side of the body.
-The cerebrum can be divided into four lobes.

Question 38

Cerebellum function / role

Answer 38

-This area is concerned with muscular movement, posture and balance,

-It does not initiate, but coordinates.

-This means damage to the cerebellum can lead to jerky and uncoordinated movement.

Question 39

Medulla Oblongata function / role

Answer 39

Contains many important regulatory centres for autonomic nervous system.
Controls unconscious and reflex actions.

Question 40

Hypothalamus function / role

Answer 40

-Main controlling region for the autonomic nervous system - with a centre for both sympathetic and parasympathetic systems.

-Controls complex behaviour patterns such as feeding, sleeping and aggression.

-Monitors the composition of blood plasma.

-Produces hormones.

Question 41

Pituitary Gland function / role

Answer 41

-Controls most of the glands in the body, and has two sections.

-Anterior Pituitary Gland - produces 6 hormones including FSH which is involved in reproduction and growth.

-Posterior Pituitary Gland - stores and releases hormones produced by the hypothalamus such as ADH.