Animal Responses

• What are the two divisions of the nervous system?

  Central Nervous System (CNS) and Peripheral Nervous System (PNS)
• What are the two components of Peripheral Nervous system?

  Sensory and Motor
• what are the two types of motor neurones?

  Somatic(voluntary) and autonomic(self-governing)
• What are the two types of autonomic motor neurones?

  Sympathetic and Parasympathetic
• Central Nervous system

  - Brain and spinal cord

  - Non-myelinated (Grey matter) ->Relay

  - Myelinated (White matter) ->Longer neurones and longer brain cells only
• Peripheral Nervous system

  Neurones carry impulses into and out of the CNS, myelinated
• Motor neurone

  Impulses from the CNS to effectors
• Sensory neurone

  Impulses from receptors to the CNS
• Somatic (voluntary) nervous system (SNS)


  - In control

  - Impulses from CNS to skeletal muscle

  - Myelinated neurones ->fast

  - Only 1 neurone in pathway

  - No synapse
• Autonomic (self regulating) nervous system

  -Unconscious

  
  

  -Impulses from CNS to cardiac muscle/smooth muscle/glands

  Cardiac muscle - to control speed of SAN

  Smooth muscle - iris, airways, blood vessels

  
  

  -Neurones are non-myelinated

  Slight delay

  Saves energy

  
  

  -At least 2 neurones (connect at a ganglion) in pathway to effectors

  Synapse present
• Ganglion

  A cluster of nerve cell bodies, often of similar function, located in the PNS.

  
• Sympathetic nervous system

  -Active in times of stress

  -Neurotransmitter: Noradrenaline

  -Speed up
• Parasympathetic nervous system

  -Active in sleep and relaxation

  -Slow down

  -Neurotransmitter: Acetylcholine
• What is the relationship between sympathetic and parasympathetic nervous system?

  They are antagnostic
• What happens to sympathetic and parasympathetic nervous system, in resting conditions?

  Action potentials pass along both neurones with equal frequency
• Describe the sympathetic nervous system

  - Many nerves leading out of the CNS, each leading to a separate effector

  
  

  -Ganglia just outside the CNS

  
  

  -Short pre-ganglionic neurones

  
  

  -Long post-ganglionic neurones (variable in length, dependent upon the position of the effector)

  
  

  -Noradrenaline

  
  

  -Increases activity - prepares body for activity

  
  

  -Stressful events

  
  

  -Increases heart rate, dilates pupils, increases ventilation rate, reduces digestive activity

  
• Describe the parasympathetic nervous system

  - Few nerves leading out of the CNS, each divide and leading to a different effector

  
  

  -Ganglia in the effector tissue

  
  

  -Long pre-ganglionic neurones (variable in length, dependent upon the position of the effector)

  
  

  -Short post-ganglionic neurones

  
  

  -Acetylcholine

  
  

  -Decreases activity - conserves energy

  
  

  -Relaxation or sleep

  
  

  -Decreases heart rate, constricts pupils, decreases ventilation rate, increases digestive activity

  
• Describe the blinking/corneal reflex

  -Cranial reflex ->unconscious part of the brain

  -Protective
• Blinking reflex and how it can be overriden

  1) Stimulus - foreign object

  2) Sensory neurone

  3) Relay non-myelinated neurone (unconscious)

  Inhibitory myelinated neurone (conscious) - opens a negative charge ion channel, causing hyperpolarisation

  4) Motor neurone

  5) Orbicularis oculi muscle contract or doesn't

  6) Response blink or no blink
• Describe the knee jerk reflex

  -Maintaining balance

  -Spinal reflex

  -No relay neurone, so quicker, but cannot be overidden

  -Tested by doctors
• Knee jerk reflex

  1)Someone hitting the knee cap

  2)Detected by the stretch receptor in the quadriceps

  3)Sensor neurone

  4)Spinal cord

  5)Motor neurone

  6)Effector - quadriceps contract
• Outline a diagram of the brain

  
• Cerebrum

  -2 hemispheres connected by the corpus callosum

  -Outermost layer is highly folded forming the cerebral cortex

  - More surface area for more processing

  -Controls conscious activities

  -Forebrain
• Cerebral cortex

  -Controls higher brain functions

  -Speech, override reflexes, factual memory, judgement, emotions, problem solving, conscious thought complex decision, reasoning

  
  

  -Sensory areas: receive inputs from receptors

  -Association areas: compare input with past experience to interpret meaning

  -Motor areas: send impulses to effectors. Each side of the brain operates the opposite side of the body
• Cerebellum

  -Hindbrain

  -Unconscious activities

  -Maintaining balance, judging distance, tensing of muscles in response to objects, feedback information on muscle position to allow fin muscle movement

  
  

  - Impulses from the cerebellum travel to the motor areas so that the motor output to the effectors can be adjusted as necessary

  
  

  -Receives information from the retina (light), semi-circular canals (balance), spindle fibres (muscles), joints (stretch receptors)
• Medulla oblongata

  -Controls the cardiac and involuntary muscle

  - Contains:

  The cardiac centre - regulating the heart

  The respiratory centre - controls and regulates breathing

  The vasomotor centre - regulates circulation and blood pressure
• Hypothalamus

  -Controls homeostatic mechanisms

  -Receives sensory input from temperature receptors and osmoreceptors

  -Regulates the pituitary gland

  Posterior: linked to hypothalamus via neurosecretory cells, releasing ADH

  Anterior: produces hormones, released in response to release factors made by the hypothalamus
• Corpus callosom


  Transmit information between hemispheres
• What are the body's responses to stress?

  Pupils dilate

  
  

  Heart rate and blood pressure increase

  
  

  Arterioles to digestive system and skin constrict

  
  

  Arterioles to muscle and liver dilate

  
  

  Blood glucose levels increase

  
  

  Metabolic rate increases

  
  

  Erector pili muscles cause hairs to stand on end

  
  

  Ventilation rate and depth increase

  
  

  Endorphins are released in the brain

  
  

  Sweat production increases

  
  

  Smooth muscle around bronchioles relaxes
• What happens if a threat is perceived?

  It stimulates the hypothalamus.

  
  

  The hypothalamus now increases activity in the

  sympathetic nervous system (part of the autonomic system) and stimulates the release of hormones from the anterior pituitary gland.
• Explain the action of a hypothalamus

  
• CRH

  corticotropin releasing hormone
• TRH

  thyrotropin releasing hormone
• ACTH

  adrenocorticotropic hormone
• TSH

  thyroid stimulating hormone
• What does cortisol do?

  Causes glycogen hydrolysed to be glucose
• Thyroxine

  -Increases metabolism

  -Make cells more responsive to adrenaline
• How is the hypothalamus and adrenaline connected?

  Leads to the release of adrenaline (from the adrenal medulla) into the blood stream.

  
  

  Produce a more prolonged response.
• Mechanism of adrenaline action

  - Adrenaline is a protein, and therefore binds to a receptor on the target cell membrane, acting as a first messenger

  
  

  • The receptor is associated with a G protein on the inner surface of the membrane, which is stimulated to activate adenyl cyclase within the cell.

  
  

  • Adenyl cyclase converts ATP to cyclic AMP

  
  

  • cAMP activates enzyme action within the cell

  
  

  • cAMP is the second messenger

  
• How does the heart responds by doing vigorous exercise?

  - Increase heart rate

  - Increase the strength of contraction

  -Increase the stroke volume