The nervous system and the endocrine system

• Describe the divisions of the nervous system (6)

  • The nervous system is divided into the central NS and the peripheral NS
  • the CNS comprises the brain and spinal cord
  • PNS is further divided into the somatic nervous system and the autonomic nervous system (ANS)
  • the somatic nervous system consists of sensory and motor neurons to carry sensory and motor information to and from the CNS and also enables reflex actions
  • the ANS acts largely unconsciously/involuntary
  • the ANS is divided into the sympathetic nervous system (SNS) and the parasympathetic nervous system (PNS)
• Effectors are muscles and glands.
• The somatic nervous system connects the central nervous system and the senses.
• The endocrine system secretes hormones into the bloodstream which are required to regulate many bodily functions such as metabolism, growth or reproduction.
• The parasympathetic nervous system is responsible for the 'rest and digest' response. It restores normal physiological processes when the threat has passed such as slowing down breathing and heart rate.
• The nervous system is divided into the central and peripheral nervous systems.
• The Central nervous system (CNS) comprises the brain and spinal cord.
• The peripheral nervous system is further divided into the somatic nervous system and the autonomic nervous system (ANS).
• The somatic nervous system consists of sensory and motor neurons to carry sensory and motor information to and from the central nervous system (CNS) and also enables reflex actions.
• The autonomic nervous system (ANS) acts largely unconsciously/involuntarily. It is divided into the sympathetic nervous system (SNS) and the parasympathetic nervous system (PNS).
• The sympathetic nervous system (SNS) prepares us for fight-or-flight response, which is activated during stressful or threatening situations.

  • It increases heart rate, dilates pupils and inhibits non-essential processes like digestion.
• Give two differences between the autonomic nervous system and the somatic nervous system (2)

  • the autonomic nervous system is involuntary whereas the somatic nervous system is under conscious control.
  • ANS controls smooth muscles and glands whereas the SNS controls skeletal muscles.
• Identify two components of the peripheral nervous system, and explain two differences in their organisation and/or functions (4)

  • the SNS has sensory and motor pathways, while the ANS is purely motor
  • the ANS controls internal organs and glands of the body while the SNS controls skeletal muscle, movement etc
• Briefly explain one function of the endocrine system (2)

  • To secrete the hormones which are required to regulate many bodily functions.
  • To provide a chemical system of communication via the bloodstream.
• The endocrine system helps to regulate the activity of cells and organs in the body.
• The thyroid gland produces thyroxine, which increases heart rate and metabolic rates.
• The pineal gland produces melatonin, which may help regulate the sleep-wake cycle.
• The anterior pituitary gland secretes Luteinizing hormone (LH) & Follicle-stimulating hormone (FSH), which stimulate ovaries to produce oestrogen & progesterone.
• The anterior pituitary gland secretes LH & FSH, which stimulate the testes to produce testosterone & sperm.
• The pancreas secretes insulin and glucagon, which help regulate blood sugar levels.
• The hypothalamus connects the endocrine system and the nervous system.
• The pituitary gland is known as the 'master gland', it releases hormones that influence other glands.

  • for example, it releases ACTH to stimulate the adrenal glands.
• Describe the structure and function of a neuron (6)

  • Neurons enable communication within the nervous system
  • the cell body (soma) contains the genetic material
  • branch-like dendrites extend from the cell body (often with dendritic spines)
  • dendrites carry functional information towards the cell body
  • dendrites can receive information from other neurons
  • axons carry messages away from cell body
  • axons can by myleinated to increase speed of nerve transmission (saltatory conduction between nodes of Ranvier)
  • terminal buttons are at the end of axons, these make synaptic connects with other cells
  • axons terminals contain neurotransmitters