The Brain

The Brain The largest and most complex organ of the nervous system Oversees many aspects of physiology such as Sensation and perception Movement Thinking

meninges Thin membrane located between the bone and brain/spinal cord Protection

meninges 3 layers Dura mater Arachnoid mater Pia mater

Dura mater Outermost layer Tough, white connective tissue, blood vessels and nerves Continues into vertebral canal as it surrounds the spinal cord

Arachnoid mater Middle layer Thin, weblike membrane that does not have blood vessels Cerebrospinal fluid (CSF) located between arachnoid mater and pia mater

Pia mater Innermost layer Many blood vessels Attached to surface of brain

parts of the brain Cerebrum Diencephelon Cerebellum Brainstem

cerebrum Largest part of brain Divided into 2 hemispheres A broad flat bundle of axons connects them, called the corpus callosum A layer of the dura mater separates the hemispheres

cerebrum The ridges are called gyri The grooves are called sulci Deep sulci are called fissures Outer layer of cerebrum is gray matter called the cerebral cortex Inner layer of cerebrum is white matter

Lobes of cerebrum Frontal lobe Parietal lobe Temporal lobe Occipital lobe

Frontal lobe Higher intellectual processes for concentrating, planning, complex problem solving, and judging consequences of behavior Movements of voluntary skeletal muscles

Parietal lobe Sensations of temperature, touch, pressure, and pain Understanding speech and using words to express thoughts and feelings

Temporal lobe Hearing Interpret sensory experiences and remember visual scenes, music, and other complex sensory patterns

Occipital lobe Vision Combine visual images with other sensory experiences

diencephalon Region of the brain that gives rise to posterior forebrain structures Associated with the Limbic System – controls emotion Thalamus Hypothalamus Pituitary gland Pineal gland Amygdala Hippocampus

thalamus Relay sensory and motor information to cerebral cortex Regulates consciousness, sleep and alertness

hypothalamus Link between nervous system and endocrine system Releases hormones that eventually control body temperature, hunger, parenting behaviors, thirst, sleep, and circadian rhythms

Pituitary gland Endocrine gland stimulated by hypothalamus that secretes hormones that regulate homeostasis

Pineal gland Secretes the hormone melatonin, which regulates sleep/wake cycles and mood

amygdala Role in memory, decision-making, and emotional reactions

hippocampus Involves consolidation of short-term memory into long term memory and spatial navigation

cerebellum A large mass of tissue inferior to cerebrum, posterior to brainstem Communicates with other brain structures by means of cerebellar peduncles. Integrates sensory info such as position of body parts, coordinates muscle activities, maintains posture

brainstem Connects brain to spinal cord Midbrain Pons Medulla Oblongata Reticular Formation

midbrain Joins spinal cord with higher regions of the brain Reflex centers that move eyes and head, maintains posture

pons A bulge on the underside of the brainstem Relays impulses between medulla oblongata and cerebrum; regulates breathing

Medulla oblongata Enlarged continuation of spinal cord Cardiac, vasomotor, and respiratory control centers, nonvital reflex control centers

Reticular formation Network of fibers throughout brain stem Regulates sleep/wake cycles, filters sensory impulses