BIO 1004
Flora
 Divided into 2 systems
 Central (CNS)
 Control center of the body
 Relays, processes, and analyzes information
 Peripheral (PNS)
 Receives info from the environment and relayed commands
of CNS to organs and glands
 Consists of brain and spinal cord
 Brain and spinal cord are wrapped in three layers of
connective tissue called meninges
 Between meninges and CNS tissue is a space filled
with cerebrospinal fluid
 Cerebrospinal fluid – bathes the brain and acts as a
shock absorber for CNS
 Fluid also allows for the exchange of nutrients and waste
between blood and tissue
 3 parts
 Cerebrum
 Cerebellum
 Brain stem
 Cerebrum – largest part of brain
 Responsible for voluntary/conscious activities
 Site of intelligence, learning, and judgment
 Hemispheres of brain are connected by the corpus
collosum
 Hemispheres are divided into lobes
 Frontal
 Parietal
 Temporal
 occipital
 Each hemisphere controls the opposite side of the
body
 Right hemisphere – responsible for creativity and artistic
ability
 Left hemisphere – responsible for analytical and
mathematical ability
 Consists of 2 layers
 Outer layer - consists of gray matter
 Gray matter - densely packed nerve cell bodies
 Processes information from sense organs and controls body
movements
 Inner layer – white matter
 Made of bundles of axons and myelin sheaths
 Connects cerebral cortex and brain stem
 Cerebellum – 2nd largest region of brain
 Located in back of skull
 Coordinates and balances actions of muscles
 Brain Stem – connects brain to spinal cord
 2 parts
 Pons and medulla oblongata
 Both regulate flow of information between brain and body
 Ex: blood pressure, heart rate, breathing, etc.
 Found between brain stem and cerebellum
 Thalamus – receives messages from all sensory receptors
in body and relays information to proper region of
cerebrum
 Hypothalamus – control center for recognition and
analysis of hunger, thirst, fatigue, anger, and bodily
temperature
 Main communication link between brain and body
 31 pairs of spinal nerves that connect brain to the body
 Reflexes are processed by the spinal cord
 Reflex – quick/automatic response to a stimulus
 Does not involve brain
 Lies outside CNS
 Consists of all nerves and cells that are not brain and
spinal cord
 Consists of 2 divisions
 Sensory (afferent) – transmits impulses from sense
organs to the CNS
 Motor (efferent) – transmits impulses from the CNS to
muscles and glands
 Consists of 2 parts
 Somatic – regulates activities under conscious control
 Ex: moving toes and fingers
 Reflex arc
 Autonomic – regulates activities that are automatic or
involuntary
 Control portions of the body that are not under conscious
control
 Controls organs
 2 parts
 Both have opposite effects on the same organ
 Sympathetic
 Ex: increases heart rate
 Parasympathetic
 Decreases heart rate