Nervous System And Endocrine System

Question 1

What is the nervous system?

Answer 1

Network of nerve cells (neurones) that pass electrical impulses along their length- they stimulate their target cells by secreting neurotransmitter onto them

Question 2

What is the nervous system made up of?

Answer 2

Central nervous system (CNS) and peripheral nervous system (PNS)

Question 3

What are the 2 main functions of the nervous system?

Answer 3

1- collect, process and respond to information in the environment
2- coordinate the workings of different organs and cells in the body

Question 4

What is the CNS made up of?

Answer 4

Brain and spinal cord

Question 5

Briefly outline the structure and function of the brain

Answer 5

Centre of all conscious awareness. Outer layer of the brain, cerebral cortex is highly developed in humans and is what distinguishes our higher mental functions from those of animals

Question 6

Briefly outline the structure and function of the spinal cord

Answer 6

Column of nervous tissue extended from the brain with emerging interval pairs of nerves- responsible for reflex actions and connects neurones to the PNS

Question 7

The PNS sub-branches into…

Answer 7

Somatic nervous system and autonomic nervous system

Question 8

The autonomic nervous system sub-branches into…

Answer 8

Sympathetic nervous system and the parasympathetic nervous system

Question 9

Briefly outline the structure and the function of the PNS

Answer 9

All nerves out of the CNS make up the PNS and there are 2 main divisions of the PNS= somatic and autonomic nervous system. The function of this part of the nervous system is to transmit action potentials (electrical impulses) from the CNS to the entirety of the body and from the body back to the CNS

Question 10

Briefly outline the structure and the function of the somatic nervous system

Answer 10

Made up of 12 pairs of cranial nerves (nerves that emerge from the direct underside of the brain) and 31 pairs of spinal nerves (from the spinal cord); these nerves have both sensory and motor neurones. Somatic nervous system ultimately controls voluntary movement but also involved in reflex actions without involvement of CNS = reflexes occur rapidly and can prevent brain being ‘overloaded’

Question 11

Briefly outline the structure and the function of the autonomic nervous system

Answer 11

Governs vital involuntary functions: heart rate, digestion, sexual arousal and stress responses- ANS comprised of sympathetic and parasympathetic nervous system

Question 12

Outline the role of the sympathetic nervous system

Answer 12

Primarily involved in responses that help us to deal with emergencies (fight or flight response) e.g. increasing heart rate and dilated pupils. Neurones from SNS travel to the majority of organs and glands within the body preparing the body for the rapid action necessary when the individual is under threat (stressor perceived).SNS also decrease certain bodily processes in stressful processes e.g. digestive activity.

Question 13

The sympathetic nervous system works in opposition to the

Answer 13

parasympathetic branch of the ANS (form of homeostasis to ensure balance is maintained)

Question 14

What are the effects on the body when the SNS is activated?

Answer 14

• dilated pupils= increase surface area for light to enter the iris = increased vision
• increased heart rate= increased blood flow to skeletal muscles
• storage polysaccharide glycogen in the liver hydrolysed to glucose (respiratory substrate)
• sweat glands stimulated= produce more sweat
• ADRENAL MEDULLA STIMULATED TO RELEASE ADRENALINE

Question 15

Outline the role of the parasympathetic nervous system?

Answer 15

Division of the ANS which controls the relaxed state of the body aka the ‘rest and digest’ state, conserving resources and promoting digestion and metabolism inhibited when sympathetic nervous system activated

Question 16

The work of the nervous system is supplemented by

Answer 16

The endocrine system

Question 17

What is the role of the endocrine system?

Answer 17

Produces hormones (chemical messengers) transported in blood plasma to their target cells which have specific receptors on their cell-surface membranes and the change in concentration of hormones stimulates them- system regulated by negative feedback processes

Question 18

What are some key differences between the nervous system and the endocrine system?

Answer 18

Nervous system:

• communication is by nerve impulses
• transmission is by neurones
• transmission is very rapid
• nerve impulses travel to specific parts of the body
• response is localised
• response is rapid
• response is short-lived
• effect is usually temporary and reversible

Hormonal system:

• communication by hormones(chemicals)
• transmission is by the blood system
• transmission is usually relatively slow
• hormones travel to all parts of the body, but only target cells respond
• response is widespread
• response is slow
• response is often long-lasting
• effect may be permanent and irreversible

Question 19

Explain how the timing of hormone release and levels of hormone released are critical for normal functioning

Answer 19

Too much/too little at the wrong time can result in dysfunction of bodily systems e.g. too high a level of cortisol can lead to Cushing’s syndrome characterised by high blood pressure and depression. Most common cause is tumour in the pituitary gland which produces excessive amounts of hormone ACTH which stimulates adrenal glands to produce too much cortisol

Question 20

Endocrine glands produce and secrete hormones to major glands of the endocrine system which include:

Answer 20

1- pituitary gland
2- adrenal gland
3- reproductive organs (ovaries and testes)

Question 21

Outline the function of the pituitary gland

Answer 21

• referred to as the ‘master gland’ as it produces hormones that influence the release of hormones from other endocrine glands e.g. stimulate adrenal glands to secrete cortisol and secretes oxytocin which stimulates the contraction of the uterus in childbirth causing the cervix to widen for delivery; so pituitary gland regulates many of the body’s functions
• controlled by hypothalamus (region of the brain just above the pituitary gland)
• high levels of hormones produced in other endocrine glands can prevent the hypothalamus and pituitary gland from releasing more of their hormones = negative feedback = prevents hormone levels rising too high

Question 22

Outline the function of the adrenal glands

Answer 22

• two adrenal glands sit on top of the kidneys and each adrenal gland is made up of 2 distinct parts: outer region of each gland = adrenal cortex and inner region= adrenal medulla
• adrenal cortex produces cortisol which regulates variety of vital bodily functions such as cardiovascular and anti-inflammatory functions
• adrenal medulla releases adrenaline and noradrenaline- hormones that prepare the body for flight or fight response

Question 23

Outline the role of the ovaries

Answer 23

• two ovaries part of the female reproductive system and responsible for the production of ova (eggs) along with the hormones oestrogen and progesterone
• progesterone is responsible for thickening the lining of the uterus each month in preparation to receive and implant a fertilised ovum