The Nervous System and the Endocrine System

Question 1

Divisions of the nervous system cns

Answer 1

Cns

brain

spinal cord

Question 2

Divisions of the nervous system pns short

Answer 2

pns
somatic nervous system

Question 3

Divisions of the nervous system pns long

Answer 3

autonomic

sympathetic

parasympathetic

Question 4

Central Nervous System

Answer 4

CNS passes messages to/from the brain and connects nerves to PNS.

Brain: center of all conscious awareness.

Spinal cord: extension of the brain, responsible for reflexes.

Question 5

Peripheral Nervous System (PNS)

Answer 5

Sends information to the CNS from the outside world and transmits messages from the CNS to muscles/glands in the body.

Question 6

two divisions of the pns

Answer 6

• Autonomic Nervous System (ANS): governs functions such as breathing, heart rate, digestion etc. Two subdivisions: sympathetic and parasympathetic.
• Somatic Nervous System: control muscle movement and receives information from sensory.

Question 7

Autonomic Nervous System: Sympathetic and Parasympathetic

Answer 7

Parasympathetic: normal resting state for the ANS ‘rest and digest’.

Sympathetic: physiologically aroused – stress hormone adrenaline released from adrenal medulla into blood stream ‘fight or flight’ response.

Question 8

Sympathetic state features

Answer 8

increase heart rate

increases breathing rate

dilates pupils

inhibits saliva production

inhibits digestion

contracts rectum

Question 9

parasympathetic state features

Answer 9

decrease heart rate

decreases breathing rate

contrstics pupils

stimulates digestion

stimulates saliva production

reales rectum

Question 10

The Endocrine System

Answer 10

A major information system in the body. Glands (organ in the body that synthesizes hormones) release hormones directly into the blood stream to a target organ.

Question 11

Thyroid

Answer 11

• Produces thyroxine.
• Affects heart rate (increases), metabolic rate and growth rate.

Question 12

Pituitary

Answer 12

• Master gland.
• Hypothalamus controls the pituitary gland via signals.

Question 13

Endocrine and ANS: fight or flight

Answer 13

1. Amygdala identifies a threat: part of the brain that senses fear.
   a. Sends message to the hypothalamus.
   b. This tells the SNS to trigger.
2. SNS sends message to adrenal medulla.
   a. This puts adrenaline into the blood stream.
3. Adrenaline in bloodstream triggers fight or flight.
   a. Various physical changes result (e.g., increased heart rate)
4. Once danger has gone, adrenaline decreases, and body goes back into parasympathetic state.

Question 14

Synaptic Sequence

Answer 14

Stage 1: No stimulation (rest).
Stage 2: Stimulation is applied + strong simulation leads to impulse.
Stage 3: The impulse is transmitted further.
Stage 4: The impulse is transmitted to another neuron.

Question 15

Synaptic Transmission

Answer 15

The process by which neighboring neurons communicate with each other by sending chemical messages across the synapse that separates them.
Neural network: neuron that communicate within a group.

Tiny gap between each neuron
Signal within neurons = electrical
Signals between neurons = chemical

• Electrical impulse reaches presynaptic terminal, neurotransmitters released from synaptic vesicles.
• Each neurotransmitter has its own postsynaptic receptor site and can have specialist functions.

Question 16

Excitation

Answer 16

• Excitatory: Neurotransmitter that increases the positive charge of the postsynaptic neuron. This increases the likelihood that the neuron will fire and pass on the electrical impulse. Example: Adrenaline.

Question 17

• Inhibitory:

Answer 17

Neurotransmitter that increases the negative charge of the postsynaptic neuron. This decreases the likelihood that the neuron will fire and pass on the electrical impulse. Example: Serotonin

Question 18

Summation

Answer 18

• When the excitatory and inhibitory influences on the postsynaptic neuron are summed.
• An action potential of the postsynaptic neuron is only triggered if the sum of excitatory and inhibitory signals reaches a threshold.

Question 19

Question: Briefly outline how excitation and inhibition are involved in synaptic transmission. (4 marks)

Answer 19

Excitatory neurotransmitters increase the positive charge of the postsynaptic neuron, increasing the likelihood that the neuron will fire and pass on the electrical impulse. Inhibitory neurotransmitters increase the negative charge of the postsynaptic neuron, decreasing the likelihood that the neuron will fire and pass on the electrical impulse. The neurotransmitters undergo a process of summation, where their influences on the postsynaptic neuron are summed, and if the sum reaches a particular threshold, the action potential of the postsynaptic neuron is triggered.