Life Science

• Responding to the environment (humans)

  • Human nervous system
  • Central nervous system
  • Peripheral nervous system
  • Autonomic nervous system
  • Structure and functioning of a nerve
  • The simple reflex arc
  • Disorders of the CNS
  • Receptors
  • Human eye
  • Human ear
• Responding to the Environment (plants)

  • Plant hormones
  • Plant defence mechanisms
• Endocrine and Homeostasis (humans)


  • Endocrine system
  • Introduction – Homeostasis
  • Homeostasis: Negative feedback mechanisms
• Human Reproduction


  • Structure of the male reproductive system
  • Structure of the female reproductive system
  • Puberty
  • Gametogenesis
  • Menstrual cycle
  • Fertilisation and development of zygote to blastocyst
  • Implantation, gestation and the role of the placenta
• Reproduction in Vertebrates


  • Diversity of reproductive strategies
• DNA: Code of Life

  • DNA: location, structure and functions
  • DNA replication
  • DNA profiling
  • RNA: location, structure and function
  • Protein synthesis
• Meiosis


  • Meiosis – The process
  • Importance of meiosis
  • Abnormal meiosis
  • Comparison of mitosis and meiosis
• Genetics and inheritance


  • Concepts in inheritance
  • Monohybrid crosses
  • Sex determination
  • Sex-linked inheritance
  • Blood grouping
  • Dihybrid crosses
  • Genetic lineages/pedigrees
  • Mutations
  • Genetic engineering
  • Paternity testing
  • Genetic links
• Evolution


  • Evidence for evolution
  • Variation
  • Origin of an idea about origins (a historical development)
  • Lamarckism (Jean Baptiste de Lamarck – 1744–1829)
  • Darwinism (Charles Darwin – 1809–1882)
  • Punctuated Equilibrium (Eldredge and Gould – 1972)
  • Artificial selection
  • Formation of new species
  • Mechanisms of reproductive isolation (Keeping species separate)
  • Evolution in present times
  • Evidence of common ancestors for living hominids, including humans
  • Out-of-Africa hypothesis
• All living cells have the ability to respond to stimuli
• Nerve cells (or neurons)

  Surrounded by supporting tissue called neurologia

  
• Coordination


  The way in which RECEPTORS pick up STIMULI and then pass messages on to the EFFECTORS to bring about COORDINATED activities
• Nervous coordination


  The fastest means of coordination, by means of impulses travelling along nerves
• Chemical coordination


  A slower method of coordination, by means of chemicals called hormones which are carried in the blood
• Types of neurons


  • Unipolar neuron
  • Multipolar neuron
  • Bipolar neurons

  
• Unipolar neuron


  Sensory or afferent neuron, they take messages (impulses) to the central nervous system (brain and spinal cord)

  
• Multipolar neuron


  Motor or efferent neurons, they take messages (impulses) away from the central nervous system (brain and spinal cord)
• Bipolar neurons


  They can be found in the retina of the eye and in the olfactory of the nose
• Reflex arc


  The response of an organism to a stimulus follows a pathway in the nervous system

  
• Functions of the parts of the neuron

  • Dendrite
  • Nissl bodies
  • Cell body
  • Neurilemma
  • Myelin sheath
  • Axon
  • Node of Ranvier
  • Synaptic knob/ end feet/ motor-end plates

  
• Synapse


  A microscopic gap over which impulses are transmitted chemically from one neuron to the next

  
• How impulses cross the synapse

  1. The impulse reaches the synaptic knob

  2. The vesicles fuse with the presynaptic membrane

  3. They burst to release neurotransmitters into the synaptic gap

  4. The neurotransmitter binds to the receptors on the postsynaptic membrane

  5. Thus generates an electric impulse in the receiving neuron

  
• Significance of the synapse

  The impulse can only move in one direction because the neurotransmitter is only produced on one side of the synapse and enzymes in the receptors on the postsynaptic membrane destroy the neurotransmitter once they have crossed the synapse

  
• Brain protection


  • The cranium
  • Pia mater
  • Dura mater
  • Arachnoid
  • Subarachnoid space filled with cerebrospinal fluid

  
• Functions of parts of the brain

  • Cerebrum
  • Cerebellum
  • Hypothalamus
  • Medulla oblongata
  • Pons
  • Corpus callosum
  • White matter
  • Grey matter
  • Gyrus & sulcus

  
• Disorders of the nervous system

  • Alzheimer's disease
  • Multiple sclerosis
• Spinal cord


  An elongated, thick walled cylindrical tube which runs down the dorsal (back) side of the body

  
• Parts of the spinal cord

  • Spinal / central canal
  • Grey matter
  • White matter

  
• Functions of the spinal cord

  • It is the centre of reflex action which enables the body to respond quickly to harmful stimuli
  • It links the brain to organs, glands and muscles

  
• Types of reflex actions

  • Inborn/ unconditional
  • Learnt / conditioned
• Reflex arc


  The pathway along which a nerve impulse is carried (conducted) from a receptor to effector

  
• Parts and course of a reflex arc

  • Receptor
  • Sensory neuron
  • Interneuron
  • Motor neuron
  • Effector

  
• Types of receptors


  • Photoreceptors
  • Thermoreceptors
  • Chemoreceptors
  • Mechanoreceptors
  • Proprioceptors
• Sense organ


  A concentration of certain receptors
• Once the impulse reach your brain


  You will only then realise what has happened
• Receptor


  A specialised cell that receives stimulus from an external or internal environment
• Types of receptors


  • PHOTORECEPTORS
  • THERMORECEPTORS
  • CHEMORECEPTORS
  • MECHANORECEPTORS
  • PROPRIOCEPTORS
• Photoreceptors


  • Sensitive to light stimulus found in the eye (sight)
• Thermoreceptors


  • Sensitive to changes in temperature (hot or cold) found in the skin
• Chemoreceptors


  • Sensitive to chemicals found mainly in the nasal cavity of the nose (smell) and taste buds on the tongue (taste)