Human Bio

3 types of neurons: Sensory, Interneurons, and Motor

Sensory neurons- takes impulses from sensory receptor to CNS

Interneurons- Receive information in the CNS and send it to a motor neuron

Motor neurons- Takes impulses from the CNS to an effector (i.e. gland or

muscle fiber)

Cell body- main cell where organelles and nuclei reside

Dendrite- many, short extensions that carry impulses to a cell

body

Axon- nerve fiber) – single, long extension that carries impulses away from the cell body

Schwann cells – neuroglia that make up the myelin sheath in the PNS

Nodes of Ranvier – gaps between myelination on the axons

Saltatory conduction – conduction of the nerve impulse from node to node

Resting potential – when the axon is not conducting a nerve impulse

Action potential – rapid change in the axon membrane that allows a nerve impulse to occur

Integration- he summation of the inhibitory and excitatory signals received by a postsynaptic neuron

2 nervous divisions- Central nervous system (Brain & spinal cord) & Peripheral nervous system (Nerves & ganglia) (cell bodies)

Bones- Skull and vertebral column

Meninges- 3 protective membranes that wrap around CNS

Cerebral spinal fluid- Space between meninges is filled with this fluid that cushions and protects the CNS

Brain and spinal cord are made up of gray and white matter

Gray matter- contains cell bodies and nonmyelinated fibers

White matter- Contains myelinated axons

4 major parts of the brain: Cerebrum, Diencephalon, Cerebellum, Brain stem

Cerebrum- largest portion of the brain

Frontal lobe: Primary motor area and conscious thought

Temporal lobe: Primary auditory, smell and speech area

Parietal lobe: Primary somatosensory and taste area

Occipital lobe- Primary visual area

Cerebral cortex- thing, outer layer of gray matter

Primary motor area- voluntary skeletal muscle

Primary somatosensory area- sensory information form skeletal muscle and skin

Association areas- integration occurs here

Processing centers- Perform higher level analytical functions including Wernicke’s and Broca’s areas both involved in speech

Diencephalon include the Hypothalamus, Thalamus, and Pineal gland

Hypothalamus- Helps maintain homeostasis (hunger, sleep, thirst, body temperature and water balance) and controls pituitary gland

Thalamus- 2 masses of gray matter that receive all sensory input except smell; involved in memory and emotions

Pineal gland- Secretes melatonin that controls our daily rhythms

Cerebellum receives and intergrates sensory input from the eyes, ears, joints and muscles about the current position of the body

Midbrain- Relay station between the cerebrum and spinal cord or cerebellum; reflex center

Pons- A bridge between cerebellum and the CNS; regulate breathing rate; reflex center for head movemnts

Medulla oblongata- reflex centers for regulating breathing, heartbeat and blood pressure

Reticular formation- major component of the reticular activating system that regulates alertness

Limbic system joins primitive emotions with higher functions such as reasoning and can cause strong emotional reactions to situations but conscious thought can override and direct our behavior

Amygdala- has emotional overtones

Hippocampus- Important to learning and memory

Learning- What happens when we recall and use past memories

Memory- Ability to hold a thought or to recall past events

Short term memory- Retention of information for only a few mintues

Long term memory- Retention of information for more than a few minutes and includes episodic memory and semantic memory

Episodic memory- person and events

Semantic memory- Number and words

Skill memory- performing skilled motor activities

Language- Depends on semantic memory

The peripheral nervous system includes cranial and spinal nerves and ganglia outside the central nervous system. Divided into 2 system which are somatic and autonomic

Spinal nerves conduct impulses to and from the spinal cord

Cranial nerves conduct impulses to and from the brain

Automatic responses are called reflexes

Somatic division serves the skin, skeletal muscles and tendon

Autonomic division regulates the activity of involuntary muscles (cardiac and smooth) and glands

Sympathetic: coordinates the body for the “fight or flight” response by speeding up metabolism, heart rate and breathing while down regulating other functions

Parasympathetic: counters the sympathetic system by bringing up a relaxed state by slowing down metabolism, heart rate and breathing and returning other functions to normal