The Brain (MODULE 5) Flashcards
Structural organisation of the brain:
Central nervous system and peripheral nervous system
Central nervous system (CNS):
Brain and spinal cord
Peripheral nervous system (PNS):
All the neurones that connect the CNS to your body
Functional organisation of the brain:
Somatic nervous system and autonomic nervous system
Somatic nervous system:
System under conscious control/voluntary actions. The SNS carries impulses to muscles
Autonomic nervous system:
System under subconscious control/automatic actions. This system works constantly, and carries impulses to glands, smooth muscle and cardiac muscle
Example of somatic nervous system:
Limb movement
Example of autonomic nervous system:
Heart beat and digestion of food
Division of autonomic nervous system:
Sympathetic nervous system and parasympathetic
Difference between sympathetic and parasympathetic nervous systems:
Sympathetic: increases general activity (increase in heart rate)
Parasympathetic: decreases general activity (decrease in heart/decrease in breathing rate)
Gross structure of the brain:
Cerebrum, cerebellum, medulla oblongata, hypothalamus, pituitary gland
Cerebrum:
Controls voluntary actions, such as learning, memory, personality, conscious thought
Cerebellum:
Controls unconscious function such as posture, balance and non-voluntary movement. Coordinates movement
Medulla oblongata:
Autonomic control, such as controlling heart and breathing rate
Hypothalamus:
Thermoregulation and osmoregulation of blood plasma, producing hormone, controlling complex behaviour patterns (feeding, sleeping)
Pituitary gland:
Stores and releases hormones that regulate several body functions
Anterior pituitary:
Front section of pituitary gland, produces 6 hormones including LH and FSH
Posterior pituitary:
Back section of the gland, stores and releases hormones produced by the hypothalamus including ADH
Basic reflex arc:
Receptor -> sensory neurone -> relay neurone -> motor neurone -> effector
Examples of reflex arcs:
Knee-jerk reflex (spinal reflex), blinking reflex (brain reflex)
Knee-jerk reflex:
- leg is tapped below the kneecap (patella)
- stretch of patellar tendon acts as a tendon
- causes extensor muscles (top of thigh) to contract
- relay neurone inhibits the motor neurone in the flexor muscle, causing it to relax
- the SIMULTANEOUS relaxation and contraction causes the leg to kick
What does the absence of the knee-jerk reflex indicate?
Nervous problems (multiple kicks may indicate cerebellar disease)
Purpose of the knee-jerk reflex:
Maintain posture and balance
Blinking reflex:
- cornea stimulated
- impulse triggered along sensory neurone on the fifth cranial nerve
- impulse passes along relay neurone in the lower brain stem
- motor neurone initiates motor response to close the eyelids
- this is deemed a ‘consensual response,’ so both eyelids close