animal responses

• What is the main structure and function of the cerebrum?

  Largest part of the brain, outer layer is known as the cerebral cortex

  Made from main folds and is split into 2 hemispheres

  
  

  Conscious thoughts, language, intelligence, personality, high-level functions and memory

  CLIPHM
• What does the cerebellum coordinate?

  Movement, posture, and balance
• What is the location and role of the medulla oblongata?

  Above the spinal cord

  Centre of control of unconscious activities e.g. breathing and heart rate
• What is the function of the hypothalamus?

  Maintains homeostasis (thermoregulation + osmoregulation)
• Pituitary gland structure + function?

  Small lobed structure known as the master gland

  Secretes many hormones to coordinate several responses including osmoregulation
• What is a simple reflex arc?

  A rapid response pathway to protect you from danger, involving three neurones
• Why are simple reflexes important?

  They protect from harmful stimuli
• What is the sequence of a simple reflex arc?

  Stimulus, receptor, sensory neurone, coordinator, motor neurone, effector, response
• What comprises the central nervous system?

  Brain and spinal cord
• What is included in the peripheral nervous system?

  Receptors, sensory and motor neurones
• What is the fight or flight response?

  A series of autonomic responses occur when a mammal is exposed to danger

  Impulse is sent to the hypothalamus

  Increased impulses sent along the sympathetic nervous system and the adrenal-cortical system

  Effector glands release more adrenaline and noradrenaline

  Triggers the hypothalamus to release more ACTH
• How does the medulla oblongata respond to increased blood pressure?

  It sends impulses to decrease heart rate
• What happens when blood pH decreases?

  Heart rate increases via the sympathetic nervous system
• What triggers the release of adrenaline during danger?

  Increased impulses along the sympathetic nervous system
• What is the neuromuscular junction?

  A synapse between a motor neurone and muscle

  
• What are the similairities/differences between a neuromuscular junction (NMJ) and a cholinergic synapse (CS)?

  Similarities

  Unidirectional - neurotransmitter receptors only on post-synaptic membrane

  
  

  Differences

  NMJ - only excitatory

  CS - excitatory or inhibitory

  
  

  NMJ - connects motor neurones - muscles

  CS - connects two neurones (sensory/relay/motor)

  
  

  NMJ - end point for action potential

  CS - new action potential generated in next neurone

  
  

  NMJ - Ach binds to receptors on muscle fibre

  CS - Ach binds to receptors on post-synaptic membrane

  
• What is a myofibril?

  Made up of fused cells that share nuclei/cytoplasm (sarcoplasm) and many mitochondria

  Millions of muscle fibres make myofibrils - bringing about movement
• What are the types of muscle tissue?

  • Skeletal muscle: Movement of the skeleton
  • Cardiac muscle: Myogenic tissue for pumping blood
  • Smooth muscle: Lines arteries, veins, bronchi

  
• What is the role of tropomyosin in muscle contraction?

  It covers binding sites on actin filaments
• How does ATP contribute to myofibril contraction?

  It releases energy for muscle movement
• What is the function of myosin in muscle contraction?

  It pulls actin during the power stroke
• What happens during the hydrolysis of ATP?

  ATP breaks down to ADP and Pi, releasing energy
• What is the role of calcium ions in muscle contraction?

  They bind to troponin, exposing actin sites
• What occurs during the power stroke in muscle contraction?

  Myosin heads pull actin, causing contraction
• How does ATP affect the myosin head during contraction?

  It allows myosin to detach from actin
• What happens when tropomyosin is pulled away from actin?

  Binding sites for myosin heads are exposed
• What is the actin-myosin cross bridge?

  It forms when myosin heads bind to actin
• Nervous system structure:


  Central nervous system = brain and spinal cord

  Peripheral nervous system = receptors, sensory and motor neurones
• Importance of simple reflexes:


  • Rapid - short pathway only three neurones & few synapses
  • Autonomic - conscious thought not involved - spinal cord coordination
  • Protect from harmful stimuli e.g., burning
• What is the role of the medulla oblongata?


  Controls heart rate and breathig rate via the autonomic nervous system

  Uses sympathetic and parasympathetic nervous systems to control SAN rhythm
• Response to blood pressure:


  Stimulus- Increased pressure

  Receptor– Pressure receptors (baroreceptors) in the wall of the aorta and carotid artery are stretched if high blood pressure

  Coordination - More electrical impulses are sent to the medulla oblongata and then impulses are sent via the PNS to SAN to decrease electrical impulses.

  Effector - Cardiac muscle

  Response – Reduced heart rate
• Response to blood pH?


  Stimulus - Decreased pH

  Receptor – Chemoreceptor in the wall of the aorta and carotid artery

  Coordination - More electrical impulses sent to the medulla oblongata and then impulses are sent via the SNS to SAN to increase electrical impulses.

  Effector - Cardiac muscle

  Response – Increased heart rate
• Define and outline the process of flight or fight:

  A series of autonomic responses occur when a mammal is exposed to danger

  Impulse is sent to the hypothalamus

  Increased impulses sent along the sympathetic nervous system and the adrenal-cortical system

  Effector glands release more adrenaline and noradrenaline

  Triggers the hypothalamus to release more ACTH
• What are the 3 muscle types? (brief description of each)


  Skeletal muscle

  • movement of the skeleton

  Cardiac muscle

  • myogenic tissue for pumping blood

  Smooth muscle

  • lines arteries, veins, bronchi
• What two systems have an effect on heart rate?

  Endocrine and nervous systems
• What are the 3 effects adrenaline has on the heart?


  Increases heart rate

  Increases stroke volume

  Increases cardiac output
• Nervous control of the heart:

  The cardiovascular centre in the medulla oblongata in the brain controls the heart rate, via the autonomic nervous system

  The heart and medulla oblongata are connected via two nerves that are connected to the SAN;

  • increases in heart rate are caused by impulses sent via the accelerator nerve in the sympathetic nervous system
  • decreases in heart rate are caused by impulses sent via the vagus nerve in the parasympathetic nervous system
• Why is it important to remove excess acid from the blood?


  To prevent enzymes from denaturing
• Features of skeletal muscle:

  Striated, voluntary, unbranched, multinucleated
• Features of cardiac muscle:


  Involuntary, striated, branched, intercalated discs, singly nucleated