7 Further anatomy

• Epidermis


  Outer layer of skin, no blood vessels, relatively waterproof, prevents water loss, prevents foreign substances from entering
• Dermis


  Thick, middle layer of skin, contains hair follicles, sweat and oil glands, nerve endings and capillaries, made up of fibrous and elastic tissue
• Hypodermis/Fat


  Lower layer of skin, connects skin to underlying muscles, mostly fat (adipose tissue), passageway for blood vessels and nerves
• Skin


  • Provides insulation and cushioning
  • Sebaceous gland secretes sebum to waterproof skin
  • Sudoriferous (sweat) gland secretes sweat to regulate body temperature
  • Hair follicle is structure that hair emerges from
• Functions of skin


  • Regulation of body temperature
  • Protection and immunity
  • Physical/mechanical
  • Chemical
  • Biological
  • Sensations
  • Excretion
  • Synthesis of vitamin D
• Brain stem


  Respiratory and cardiovascular control centre
• Diencephalon


  Thalamus and hypothalamus
• Thalamus


  Gatekeeper, relays sensory information to other parts of the brain
• Hypothalamus


  Controls the autonomic nervous system, regulates vital body functions
• Cerebrum


  High-level functions (thinking, language, emotion, motivation)
• Cerebellum


  Co-ordination of muscle contraction, posture and balance
• Lobes of the cerebrum

  • Frontal lobe
  • Parietal lobe
  • Occipital lobe
  • Temporal lobe
  • Limbic lobe
• Brain function


  1. Sensory (receiving sensory impulse)

  2. Association (interpreting, storing, deciding response)

  3. Motor (transmitting impulses to effectors)
• Blood-brain barrier (BBB)


  Highly selective semi-permeable membrane that maintains a constant environment for the brain, separates circulating blood from the brain
• BBB structure


  • Endothelial cells line blood vessels
  • Tight junctions between cells
  • Pericytes regulate blood flow
  • Astrocytes connect neural signalling to CNS blood vessels
  • Macrophages protect from foreign substances
• Energy for the brain

  Glucose and oxygen allow aerobic respiration to produce ATP, brain uses about half the body's sugar energy
• With low glucose or oxygen, mental confusion, dizziness, convulsions and loss of consciousness may occur
• Major arteries supplying the brain

  • Right common carotid artery
  • Right internal carotid artery
  • Right subclavian artery
  • Left internal carotid artery
  • Left external carotid artery
  • Brachiocephalic trunk/artery
  • Left common carotid artery