Module 5 Communication, homeostasis & energy Block 2C – 5.5 Animal responses 5.5.6 The brain

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Learning Outcomes Label the gross structure of the human brain (Grade E - D) Outline the function of the cerebrum, cerebellum, medulla oblongata, hypothalamus and pituitary gland (Grade C –B) Describe the role of the brain and nervous system in coordinated muscular movement (Grade B – A) To understand the structure of the human brain 5

Match up A) Sensory areas B) Association areas C) Motor areas Compare input with previous experiences in order to interpret what the input means and judge an appropriate response Sends impulses to effectors (muscles and glands) Receives impulses indirectly from the receptors A) Sensory areas B) Association areas C) Motor areas A3, B1 and C2

Central Nervous System Spinal cord Runs through the vertebral column Sensory and motor spinal nerves are connected to it Quick reflex actions processed Brain Inside the protective bony cranium (skull) Massive bunch of relay neurones connected to spinal cord

Gross Structure of Brain http://www.youtube.com/watch?v=snO68aJTOpM Use a balloon as a model of the draw on the sections and label Use page 228

Regions of the Brain

Regions of the brain Hindbrain Midbrain Medulla oblongata – controls vital functions such as heart and ventilation rates, peristalsis and blood pressure Cerebellum – controls balance and muscle coordination Midbrain Small in mammals Contains nerve fibres that connect fore and hindbrain

Regions of the brain Forebrain Cerebrum – controls the bodies voluntary behaviour, reasoning, personality and memory Thalamus – relays sensory information from the sense organs to the correct part of the cerebellum Hypothalamus – receives sensory information (body temp, blood solute concn)

Regions of the brain Cerebral hemispheres: act as the integrating centre for high complex functions such as learning, memory emotions and consciousness. Hypothalamus: maintains homeostasis, coordinating the nervous and endocrine systems, secreting hormones of the posterior pituitary, and releasing factors regulating the anterior pituitary. Cerebellum: coordinates unconscious functions, such as movement and balance. Pituitary gland: the posterior lobe stores and releases hormones produced by the hypothalamus and the anterior lobe, and produces and secretes hormones regulating many body functions. Medulla oblongata: controls automatic and homeostatic activities, such as swallowing, digestion and vomiting, and breathing and heart activity.

Cerebral hemispheres The cerebrum is the largest part of the brain it is divided into 2 halves (hemispheres) The two halves are quite separate except for the corpus callosum, (a bundle of 200 million neurones which run between the two halves) The left cerebral hemisphere controls the right side of the body and visa versa

Cerebral hemispheres The cerebral hemispheres have an outer layer the cerebral cortex which contains the nerve cell bodies (grey matter) and an inner area containing nerve fibres (white matter) The cerebral cortex is highly folded and so has a large surface area. The cortex is the most complicated, fascinating and least-understood part of the brain.

Cerebral hemisphere The folds divide the cortext into 4 lobes Occipital lobe - receives and processes info from the eyes Temporal lobe - receives and interprets info from the ears, processing language and the meaning of words Parietal lobe – associated with the sensory cortex and interprets sensory info about touch, taste, pressure pain, heat and cold Frontal lobe – controls conscious motor movement, speech and thought processes

Functional areas There are 3 discrete yet interconnected areas on each cerebral hemisphere : Sensory area – receives nerve impulses from receptors Association area – analyses and interprets these nerve impulses Motor area – sends nerve impulses to effectors

Functional areas Other version

Functional areas Mapping of the Somatosensory area reflects sensitivity. Mapping of the Motor area reflects mobility. Association areas are the link between the two and are involved in thinking, reasoning, decision making, memory, emotion and learning.

Mapping of Somatosensory area Motor area

Parts of Brain Structure Description Function Cerebrum Cerebellum Medulla oblongata Hypothalamus Pituitary gland

Cerebrum Cerebellum Medulla oblongata Pituitary Gland Hypothalamus Structure Description Function Cerebrum Largest part of brain, 2 hemispheres connected via corpus callosum, surface is thin layer of nerve cells known as the cerebral cortex-highly folded Higher brain functions (e.g. conscious thought & emotional response, ability to override some reflexes, reasoning, judgement) Cerebellum Neurones carrying impulses to motor areas (contains over half of all nerve cells in brain) Coordinated motor response: balance, fine movement: (voluntary muscle movement initiated in cerebrum) but fine muscle control requires significant nonconscious operation ‘autopilot’ Medulla oblongata Found at the base of the brain, at the top of the spinal cord Controls non-skeletal muscles e.g cardiac and respiratory centre Hypothalamus Found beneath the middle part of brain Controls autonomic nervous system and endocrine glands. Homeostasis e.g. temperature, osmoregulation, hormones Pituitary Gland Small gland found at base of brain, below but attached to hypothalamus. Two lobes – anterior and posterior. Endocrine gland, anterior lobe produces and secretes many hormones - control many other glands. Posterior stores and releases hormones made in the hypothalamus. (eg ADH)

Exam questions D, B,C

Exam questions List 3 processes which the medulla oblongata controls (3 marks) Which part of the brain is responsible for conscious thought and emotions? (1 mark) Suggest why the cerebellum is sometimes referred to as the bodies auto pilot. (2 mark) Outline the role of the hypothalamus in homeostasis (4 marks)

PA Heart rate (1) Ventilation rate (1) Circulation and blood pressure (1) Cerebrum (1) The cerebrum is involved with fine control of muscular movements, such as manipulating body balance (1) Such activities often require learning, but once learned involve conscious control (1) Sensory input from temperature receptors (1) and osmoreceptors (1) is received by the hypothalamus and this leads to the initiation of nervous responses that regulate body temperature (1) and blood water potential (1).

Lesion Studies: As is often the case in medicine improved understanding of normal function often comes from the study of disease or injury. Study of when things go wrong often provides insight into normal function. Lesions are regions of damage or tissue death. Lesions of brain result in a loss or alternation of behaviour linked to the region of the brain affected by the lesion.

Lesion Studies: Legions in the Broca’s area in the left cerebral hemisphere cause dysphasia – inability to speak but reading and writing are still possible.

Functional magnetic resonance imaging fMRI is a technique for determining which parts of the brain are activated by specific thought processes. The fMRI shows areas of the brain which have increased blood flow. Increased blood flow is associated with increased neurone activity. When presented with a stimulus the fMRI is taken and the region of the brain with increased blood flow is linked to with the processing of that stimulus information.

Plenary Use cards to play snap with the part and function of the brain

Learning Objectives Success Criteria To understand the structure of the human brain Label the gross structure of the human brain (Grade E - D) Outline the function of the cerebrum, cerebellum, medulla oblongata and hypothalamus (Grade C –B) Describe the role of the brain and nervous system in coordinated muscular movement (Grade B – A) 30