The most complex mechanism known The Human brain The most complex mechanism known

Human brain 25 billion neurons Require continuous supply of oxygen and glucose If brain deprived of blood it results in damage (ex- stroke) Hollow organ Fluid filled spaces called ventricles

The medulla Most posterior portion of the brain stem Continuous with the spinal cord Consists of white matter (nerve tracts) and gray matter (cell bodies), carries messages to and from spinal cord Motor fibers cross here, right brain controls lefts side of body, left brain controls right side.

Medulla continued… Gray and white matter known as the reticular formation extend from the spinal cord through the medulla and upward through the brain stem and thalamus. It keeps cerebrum conscious and alert Also houses several vital reflex centers

Reflex centers of the medulla: 1. cardiac centers that control heart rate 2. vasomotor centers that help reg. blood pressure by controlling the diameter of blood vessels. 3. respiratory centers that initiate and reg. breathing.

The pons Forms a bulge on the anterior surface of the brain stem. Continuous with medulla. Consists of nerve fibers passing from medulla to other parts of the brain. Helps reg. respiration

The midbrain Shortest portion of brain stem. Has bundles of neurons connecting the lower portion of the brain with spinal cord. Contains reflex centers for vision and hearing.

The diencephalon includes thalamus and hypothalamus Major relay center Controls all sensory info except smell Hypothalamus Control center of the autonomic center. Link between mind and body. Links nervous system with endocrine system. Produces 2 hormones: ADH (anti diuretic hormone) and oxytocin.

Hypothalamus continued… Oxytocin stimulates contraction of the uterus during childbirth and release of milk). ADH (prevents production of dilute urine) and oxytocin are stored in the posterior lobe of the pituitary gland. Helps maintain fluid balance by reg. the volume of water excreted by the kidneys. Also contains a thirst center to let us know when we need fluids. Regulates body temperature

Hypothalamus continued… Appetite and satiety (fullness) regualte food intake. Influences sexual behavior, emotional aspects of sensory input, pleasure, and pain.

The cerebellum Responsible for coordination of movement 2nd largest part of the brain Contains 2 lateral masses called hemispheres and a connecting portion. Helps make movements smooth and steady rather than trembling Helps maintain muscle tone and posture Impulses from the organ of balance (vestibular apparatus) in the inner ear are continuoulst delivered to the cerebellum which maintains equilibrium.

The cerebrum Largest part of the brain and most prominent. Controls motor activities, interprets sensation, serves as the center of intellect, memory, language, and consciousness. Divided into hemispheres cerebral cortex- thin outer layer of the cerebrum, consists of gray matter

Hemispheres of the cerebrum cont… Basal ganglia- lie within the white matter of the cerebrum, play an important role in movement. The two cavities in the cerebrum are called the lateral ventricles. The brain in folded into convolutions and in between them are shallow grooves called sulci and the deep pockets are called fissures. The cerebrum is partially divided into right and left halves called the right and left cerebral hemispheres. They are separated by a deep groove called the longitudinal fissure.

The cerebrum has sensory, motor, and association functions: Sensory functions: receives info from sense receptors and interprets these messages Motor functions: motor areas of the cerebrum are responsible for all voluntary movement and for some involuntary movement Association functions: learning and reasoning, memory storage and recall, language abilities and even consciousness.

Lobes of the cerebrum specialize in certain functions Frontal lobe- motor cortex, formation of words. Parietal lobe- receives info from skin and joints integrates info with visual, auditory and sensory association. Occipital lobe- receives info from the thalamus about what we see and integrates the info in order to formulate an appropriates response.

Temporal lobe- reception and integration of auditory messages Limbic lobe- a link between emotional and cognitive thought. Central lobe- involved with somatic and autonomic activities.