Neuroscience and Nervous System: Key Concepts and Structures

Central nervous system (CNS)

Brain and spinal cord; processes information

Peripheral nervous system (PNS)

Nerves outside the CNS that transmit signals

Sensory neurons

Carry information from body to CNS

Motor neurons

Send signals from CNS to muscles or glands

Interneurons

Connect neurons within the CNS

Reflex

Rapid automatic response to a stimulus

Reflex arc

Pathway of neurons in a reflex

Dendrite

Receives incoming signals

Cell body

Processes information in neuron

Axon

Carries signal away from cell body

Synapse

Gap between neurons where communication occurs

Astrocytes

Support neurons and help form blood-brain barrier

Schwann cells

Produce myelin sheath around axons

Myelin sheath

Insulates axon and speeds up signal transmission

Resting potential

Membrane potential of a neuron at rest (-60 to -80 mV)

Sodium-potassium pump

Moves Na+ out and K+ into cell to maintain gradient

Depolarization

Na+ enters cell, making it more positive

Hyperpolarization

K+ leaves cell, making it more negative

Graded potential

Small, variable change in membrane potential

Action potential

All-or-nothing electrical signal along axon

Electrical synapse

Direct ion flow between cells

Chemical synapse

Uses neurotransmitters to send signals

Excitatory postsynaptic potential (EPSP)

Increases likelihood of action potential

Inhibitory postsynaptic potential (IPSP)

Decreases likelihood of action potential

Temporal summation

Multiple signals over time add together

Spatial summation

Signals from multiple neurons add together

Acetylcholine

Neurotransmitter involved in muscle activation

Dopamine

Neurotransmitter affecting mood and reward

Serotonin

Neurotransmitter affecting mood and sleep

Endorphins

Neurotransmitters that reduce pain

Nitric oxide (NO)

Gas neurotransmitter involved in smooth muscle control

Medulla oblongata

Controls breathing, heart rate, digestion

Pons

Regulates breathing

Midbrain

Processes sensory information

Cerebellum

Coordinates movement and balance

Thalamus

Relays sensory information

Hypothalamus

Maintains homeostasis and controls hormones

Cerebrum

Responsible for thinking and memory

Cerebral cortex

Outer layer of cerebrum for complex processing

Corpus callosum

Connects left and right hemispheres

Mechanoreceptors

Detect touch, pressure, sound

Chemoreceptors

Detect chemicals (taste, smell)

Photoreceptors

Detect light

Thermoreceptors

Detect temperature

Pain receptors

Detect harmful stimuli

Hydrostatic skeleton

Uses fluid pressure for support

Exoskeleton

Hard outer covering for support and protection

Endoskeleton

Internal skeleton made of bone

Muscle fiber

Muscle cell

Myofibril

Structure inside muscle fiber containing filaments

Sarcomere

Functional unit of muscle contraction

Sliding filament model

Actin and myosin slide to contract muscle

Actin

Thin filament in muscle

Myosin

Thick filament that pulls actin

Calcium ions (Ca2+)

Trigger muscle contraction

Skeletal muscle

Striated, voluntary muscle attached to bones

Cardiac muscle

Striated, involuntary muscle in heart

Smooth muscle

Non-striated, involuntary muscle in organs

Reproduction

Not necessary for individual survival but essential for species survival and evolution

Asexual reproduction

One parent produces genetically identical offspring

Fission

Organism splits into two equal parts

Budding

New organism grows from parent body

Fragmentation

Body breaks into pieces that grow into new organisms

Parthenogenesis

Development of offspring from an unfertilized egg

Sexual reproduction

Two parents produce genetically diverse offspring

Gametes

Sex cells (sperm and egg)

Fertilization

Fusion of sperm and egg to form a zygote

External fertilization

Fertilization occurs outside the body

Internal fertilization

Fertilization occurs inside the female body

Hermaphroditism

Organism has both male and female reproductive organs

Parental care

Energy investment in offspring that increases survival

Spermatogenesis

Process of sperm production

Oogenesis

Process of egg production

Testes

Produce sperm

Seminal vesicles

Secrete fructose-rich fluid for sperm energy

Prostate gland

Adds fluid and enzymes to semen

Bulbourethral glands

Neutralize acidity in urethra

Penis

Delivers sperm during reproduction

GnRH

Hormone that signals pituitary to release FSH and LH

FSH

Stimulates sperm and egg production

LH

Stimulates testosterone production and ovulation

Testosterone

Male sex hormone responsible for sperm production and traits

Ovaries

Produce eggs and hormones

Oviduct (fallopian tube)

Carries egg and is site of fertilization

Uterus

Site of embryo development

Endometrium

Uterine lining where embryo implants

Cervix

Opening of uterus

Vagina

Receives sperm during intercourse

Estrogen

Builds uterine lining

Progesterone

Maintains uterine lining for pregnancy

Menstrual cycle

Monthly cycle of uterine lining buildup and shedding

No fertilization

Endometrium sheds (menstruation)

Fertilization occurs

Embryo produces HCG to maintain uterine lining

HCG

Hormone that maintains pregnancy

Zygote

Fertilized egg

Cleavage

Rapid cell division after fertilization

Gastrulation

Formation of germ layers

Organogenesis

Development of organs

Cell determination

Process where cells become specialized

Fate map

Diagram showing future cell development