Biol Exam 4

Characteristics of the nervous system

\-receives information from many sources

\-integrates info

\-initiate responses

Central Nervous System

Brain and spinal cord

\-receive, process, and transfer information

Peripheral Nervous System

Nerves outside CNS

\-sensory and motor division

Neurons

Specialized cells for communication

Sensory neurons

Neurons in the PNS that receive stimuli

Interneurons

Neurons that transmit info within the CNS

Motor neurons

Transmit info away from the CNS

Neuron cell body

Has the nucleus and most of the cytoplasm and organelles

Dendrites

Small, extensions from the cell body that receive incoming info

Axon

Specialized to conduct electrical impulses away from the cell body

Neurons initiate

Action potentials

Targets

Where neurons transfer: either another neuron, muscle cell or gland

Synapse

Special junction between axon terminus and target cell

Synaptic transmission

Transmitting impulse from sending cell across synaptic cleft to receiving target

All or nothing action potential

Individual neuron threshold

Self propagating action potential

Continues to propagate itself in the next region of the axon, moves like a wave down the axon

Refractory period

Action potential must completely finish before another can be generated

\-the number of actions potentials encodes the strength of the stiumuls

Neuroglial cells

Support and protect neurons

Schwann cells

Form myelin sheaths in PNS, speed up transmission

Oligodendrocytes

Form myelin sheaths in CNS

Multiple sclerosis

\-damage of the myelin sheaths in the brain and spinal cord

\-weakness, loss of vision, impaired coordination

Nerves

\-Contains axons of many neurons wrapped together in a protective sheath

\-carries info to and from the CNS

Cranial nerves

Connect directly to the Brian

Spinal nerves

Connect directly to the spinal cord

Sensory neurons provide

Information for both the somatic and autonomic motor divisions of the PNS

Somatic Division

Voluntary and involuntary movements

Spinal reflexes

Involuntary responses mediated primarily by spinal cord and spinal nerves

Autonomic Division controls

Automatic body functions

Sympathetic divisions

Emergencies, fight or flight response

Parasympathetic division

Relaxes the body, rest and digest

CNS protections

Bone, meninges, cerebrospinal fluid, blood-brain barrier

White matter

Outer portion of spinal cord, contains sensory and motor tracts

Gray matter

Center portion of spinal cord, contains cell bodies and dendrites

Hindbrain

Coordinates basic automatic and vital tasks

Midbrain

Coordinates muscle groups and responses to sight and sound

Forebrain

Receives, integrates sensory input, determines complex behavior

Short-term memory

Working memory, stored in limbic system

Long-term memory

Information from previous days to years, permanent changes in neurons and development of additional synapl

Psychoactive drugs

Affect states of consciousness, emotions or behavior

\-able to cross the blood-brain barrier

Drug effects on brain function

Psychological dependence, tolerance, addiction, withdrawal

Concussion

Disruption of electrical activity in the brain

Encephalitis

Inflammation of the brain c

Meningitis

Inflammation of meninges caused by viral or bacterial infection

Rabies

Spreads from bite to brain

Epilepsy

Abnormal electrical activity in brain

Alzheimer’s disease

Accumulation of abnormal protein, beta amyloid

Parkinson’s disease

Loss of dopamine releasing neurons

Stimulus

Sensory input that causes some change within or outside the body

Receptor

Structure that detects stimulus and converts its energy into another form

CNS interprets nerve impulses based on

Origin and frequency

Sensory adaptation

Sensory neuron stops sending impulses even though the original stimulus is still present

Somatic sensations

Arise from receptors located throughout the body

Special senses

Arise from receptors restricted to specific areas of the body

Somatosensory area

Where impulses are sent

Sensory receptors in the skin

Unencapsulated dendrites, Merkel disks, meissner’s corpuscles, Ruffini endings, pacinian corpuscles

Mechanoreceptors

Detect limb position, muscle length, and tension

Thermoreceptors

Detect temperature

Pain receptors

\-fast pain occurs quickly

\-slow pain occurs more slowly

\-pain receptors do not adapt

Taste

Chemoreceptors bind with dissolved substances

Smell

Chemoreceptors bind with odorants

Outer ear

Pinna, auditory canal, tympanic membrane

Pinna

Outer part of ear, directs sound waves to auditory canal

Auditory canal

Directs sound waves to tympanic membrane

Tympanic membrane

Separates our outer ear from middle ear, vibrates in response to sound waves and passes along vibrations

Middle ear amplifies sound

Malleus, incus, stapes

Inner ear sorts and converts sounds

Cochlea converts sound to action potentials

\-Organ of corti: hair cells and tectorial membrane

Pressure waves result in

Physical bending of hair cells

Action potentials are carried by auditory nerves to

Vestibulocochlear nerve to brain

Vestibular apparatus

Three semicircular canals and vestibule

Head position and linear acceleration

Movement of otoliths bends hair cells in vestibule

Iris

Regulates amount of light, causes pupil to constrict or dilate

Cornea and lens

Focusing and bending of light

Myopia

Nearsightedness

Hyperopia

Farsightedness

Astigmatism

Irregularities exist in cornea or lens

Retina

Allows us to see in color, adapt to varying light intensities

Rods

Vision in dim light

Cones

Provide color vision and accurate images

Endocrine system

Collection of specialized cells and tissues that secrete hormones

Endocrine glands

Organs that secrete hormones into blood

Hormones

Chemical messengers secreted by endocrine glands

Hypothalamus

Links nervous and endocrine systems, monitors hormone secretions of the pituitary gland

Pituitary gland

Master gland, secretes 8 different hormones that regulate other endocrine organs

Hormones are made

In cell bodies in hypothalamus

Posterior pituitary hormones

Stores Antidiuretic and oxytocin hormones

Anterior pituitary

Controlled by hypothalamus and produces 6 main hormones

Prolactin

Development of milk production

Growth hormone

Effects on bone and muscle

FSH and LH

Stimulate growth and function of ovaries and testes, sexual maturation

ACTH

Stimulates adrenal cortex to release cortisol

TSH

Release of thyroid hormones

Adrenal cortex

Cortisol and aldosterone

Thyroid

Involved in calcium balance and regulating metabolism (production of ATP)

Hypothyroidism

Under active thyroid gland

Hyperthyroidism

Overactive thyroid gland

Iodine

Required for the production of thyroid hormones

Islets of langerhans

Alpha (glucagon) and beta (insulin) cells

Glucagon

Raises blood sugar

Insulin

Lowers blood sugar

Type 1 diabetes

Pancreas cannot produce insulin