Systems/ structures in the brain

Question 1

Which 2 main systems does the nervous system split into?

Answer 1

Central nervous system
Peripheral nervous system

Question 2

What are the components of the central nervous system?

Answer 2

Brain
Spinal cord

Question 3

What are the components of the peripheral nervous system?

Answer 3

Somatic nervous system
Autonomic nervous system

Question 4

What are the components of the autonomic nervous system?

Answer 4

Sympathetic nervous system
Parasympathetic

Question 5

What is the role of the components of the CNS?

Answer 5

Brain: processes info from our senses.
Brainstem: connects brain to spinal cord, controls involuntary processes e.g. heartbeat.
Spinal cord: transfers messages to and from the brain and rest of the body, simple reflex actions e.g. jumping out of your chair if you sit on a pin.

Question 6

What is the purpose of the PNS?

Answer 6

Transmit messages to and from the CNS to the rest of the body.
Made up of nerves.

Question 7

What does the somatic nervous system do?

Answer 7

Made up of sensory receptors and motor pathways.
Carries sensory information from the outside world to the brain and provide muscle responses via the motor pathways.

Question 8

What does the autonomic nervous system do?

Answer 8

Important role in homeostasis (maintains body temp, heart rate).
Only consists of motor pathways.

Question 9

What does the sympathetic nervous system do?

Answer 9

Involved in responses that prepare the body for fight or flight.
Impulses travel from it to organs when in dangerous situation e.g digestion suppressed, heart and breathing rate increase.

Question 10

What does the parasympathetic nervous system do?

Answer 10

Returns our body back to its normal ‘resting’ state
e.g. heart and breathing rate slow down, digestion starts again.

Question 11

Name the 6 structures that most cells share in common.

Answer 11

Cell body
Nucleus
Axon
Dendrites
Vesicles
Myelin sheath

Question 12

What is the cell body’s purpose?

Answer 12

Contain the nucleus

Question 13

Purpose of the nucleus.

Answer 13

Contains DNA
Controls the cell

Question 14

Purpose of the axon.

Answer 14

Carries electrical signals from dendrites to terminal buttons

Question 15

Purpose of dendrites.

Answer 15

Receive chemical messages from other neurons

Question 16

Purpose of vesicles.

Answer 16

Store neurotransmitters

Question 17

Purpose of myelin sheath.

Answer 17

Protects and speeds up impulses along the axon.

Question 18

Purpose of the synaptic gap.

Answer 18

Where an electrical impulse is transmitted to a chemical messenger that can be received by the next neuron

Question 19

Purpose of receptors.

Answer 19

Convert energy into electrical impulses

Question 20

What is the structure, function and location of sensory neurons?

Answer 20

Structure: long dendrites, short axon
Function: carry, messages from PNS to CNS
Location: in receptors all over the body e.g. eyes

Question 21

What is the structure, function and location of relay neurons?

Answer 21

Structure: short dendrites, short axon
Function: connect sensory neurons to the motor/ other sensory neurons
Location: CNS

Question 22

What is the structure, function and location of motor neurons?

Answer 22

Structure: short dendrite, long axon
Function: connect the CNS to effectors e.g. muscles and glands
Location: CNS + axons extend to muscles and glands

Question 23

Explain synaptic transmission.

Answer 23

Nueron activated by stimulus -> action potential (the elec impulse that stimulates a neuron to fire) passes down axon -> presynaptic terminal + triggers release of neurotransmitters from synaptic vesicles -> diffuse across synaptic gap -> bind to receptors on the postsynaptic membrane

Question 24

Explain excitatory neurotransmitters

Answer 24

Increases likelihood that an excitatory signal is sent to the post-synaptic neuron -> more likely to then fire
When binds with post-synaptic receptor, positive elec charge in the membrane -> excitatory post-synaptic potential (EPSP)

Question 25

Explain inhibitory neurotransmitters.

Answer 25

Increases likelihood an inhibitory signal is sent to the post-synaptic neuron -> less likely to fire When binds with post-synaptic receptors, negative elec charge in the membrane -> inhibitory post-synaptic potential (IPSP)

Question 26

What is an example of an excitatory neurotransmitter?

Answer 26

noradrenaline

Question 27

What is an example of an inhibitory neurotransmitter?

Answer 27

GABA

Question 28

What are the 2 functions of the endocrine system?

Answer 28

1. regulate cell/ organ activity + control vital physiological processes 2. release hormones from glands into the bloodstream to regulate cell/ organ activity

Question 29

What is the effect of the hypothalamus?

Answer 29

To stimulate and control the release of hormones from the pituitary gland

Question 30

What is the hormone released from and effect of the anterior pituitary gland?

Answer 30

Hormone: ACTH Effect: stimulates the adrenal cortex and release of cortisol during the stress response

Question 31

What is the hormone released from and effect of the posterior pituitary gland?

Answer 31

Hormone: oxytocin Effect: Responsible for uterus contractions during childbirth

Question 32

What is the hormone released and effect of the pineal gland?

Answer 32

Hormone: melatonin Effect: Responsible for important biological rhythms including sleep-wake cycle

Question 33

What is the hormone released and effect of the adrenal medulla?

Answer 33

Hormone: adrenaline + noradrenaline Effect: Fight or flight

Question 34

What is the hormone released and effect of the adrenal cortex?

Answer 34

Hormone: cortisol Effect: Stimulates release of glucose to provide body w/ energy, while supressing immune system

Question 35

What is the hormone released and effect of the ovaries?

Answer 35

Hormone: oestrogen Effect: Regulation of female reproductive system including menstrual cycle + pregnancy

Question 36

What is the hormone released and effect of the testes?

Answer 36

Hormone: testosterone Effect: Development of male sex characteristics during puberty + promoting muscle growth

Question 37

Explain the process of fight or flight.

Answer 37

Person enters stressful situation -> amygdala activates and sends distress signal to hypothalamus -> hypothalamus activates sympathomedullary pathway (SAM pathway - runs to adrenal medulla and sympathetic nervous system) -> SNS stimulates adrenal medulla -> adrenal medulla secretes adrenaline + noradrenaline into bloodstream -> adrenaline causes number of physiological changes, prepares for fight/ flight

Question 38

Explain the physiological effects of the fight/ flight response.

Answer 38

Increased heart rate - increase blood flow to organs + increase movement of adrenaline around the body. Increased breathing rate - increase oxygen intake. Pupil dilation - increase light entry into eye, enhance vision. Sweat production - regulate body temp. Reduction of non-essential funcitons (e.g. digestive system, urination) - increases energy for essential functions.

Question 39

What happens once the emergency stressor from a fight/ flight situation has been dealt with?

Answer 39

The parasympathetic nervous system returns the body back to its normal resting state - slows heart and breathing rate, non-essential functions start up again

Question 40

What causes the stress response system called the HPA axis (hypothalamic-pituitary-adrenal axis)?

Answer 40

If the brain receives threatening signals over an extended period of time e.g. a stressful job

Question 41

What is the 1st stage (H) of the HPA axis?

Answer 41

Hypothalamus releases a chemical messenger in response to a continued threat -> it releases corticotropin-releasing hormone (CRH) -> stimulates the pituitary gland

Question 42

What's the 2nd stage (P) of the HPA axis?

Answer 42

CRH causes pituitary gland to produce + release ACTH -> is transported (via bloodstream) to adrenal glands

Question 43

What's the 3rd stage (A) of the HPA axis?

Answer 43

ACTH stimulates adrenal cortex to release various stress-related hormones, including cortisol (which can have detrimental effects on health)

Question 44

Limitation of the fight/ flight response - maladaptive

Answer 44

Evolved as survival mechanism to situations requiring physical course of action. Modern day stressors are ones you can fight/ flee from. Increased blood pressure due to parasympa NS activation -> physical damage in blood vessels + heart disease.. Cortisol may assist fighting a viral infection/ heal damaged tissue but supresses immune response . In modern life, stress response hinders rather than helps survival.