Biological Bases of Behavior

Unit 1 AP PYSCH Lesson 4

Genetic Predisposition

the increased chance of developing a specific trait or condition due to our genetic code

Epigenetics

the study of heritable changes in gene expression that occur without alterations to the DNA sequence itself

Heritability

amount of variation among individuals that we can attribute to genetics

Turner Syndrome

Have only 1 X sex chromosome; causes short stature, webbed neckk, and abnormal sexual development

Klinefelter Syndrome

A genetic condition where males have an extra X chromosome, leading to minimal sexual development and extreme introversion/passiveness (XXY)

Down Syndrome

An extra chromosome in the 21st pair, it usually causes intellect disability and physical abnormalities

Tay-Sachs syndrome

produces progressive loss of nervous function and death in a baby

Central Nervous System

comprised of the brain and spinal cord, it processes sensory information and coordinates responses to stimuli.

Peripheral Nervous System

comprises all the nerves outside the central nervous system, they are what sense stimuli and mobilize the body's responses.

Somatic Nervous System

the component of the peripheral nervous system that controls voluntary muscular movements and transmits sensory information to the central nervous system.

Autonomic Nervous System

the part of the peripheral nervous system that regulates involuntary bodily functions, including heart rate, digestion, and respiratory rate.

Sympathetic Nervous System

a division of the autonomic nervous system that prepares the body for stress-related activities by increasing heart rate and redirecting blood flow to muscles (fight or flight response)

Parasympathetic Nervous System

a division of the autonomic nervous system that promotes the 'rest and digest' response, helping to conserve energy and restore the body to a state of calm after stress (rest and digest response)

Spinal Cord

the cylindrical structure of nervous tissue that extends from the base of the brain down the vertebral column, transmitting signals between the brain and the rest of the body; protected by membranes called meninges and your spinal column of bony vertebrae, starts at the base of your back and extends upward to the base of your skull where it joins your brain

Neuron

an individual nerve cell that transmits electrical impulses, serving as the basic building block of the nervous system, allowing communication between the brain and the rest of the body.

Gilial Cells

guide the growth of developing neurons, help provide nutrition for and get rid of wastes of neurons, and form an insulating sheath around neurons that speeds conduction; communicate with other cells w/ chemical signals

Sensory Neuron

a type of neuron responsible for carrying sensory information from sensory receptors to the central nervous system, allowing the perception of stimuli such as light, sound, and touch; located in PNS

aka as afferent neurons

Motor Neurons

neurons that transmit signals from the central nervous system to muscles and glands, facilitating movement and response to stimuli; also known as efferent neurons.

Effectors

Muscle and gland cells that produce a physiological response from motor neurons/efferents

Interneurons

neurons that connect sensory and motor neurons within the central nervous system, playing a crucial role in reflexes and processing information. (located in CNS)

Reflex Arc

A neural pathway that controls a reflex action, consisting of a sensory neuron, interneurons, and a motor neuron. It allows for immediate responses to stimuli without direct involvement of the brain. (spinal cord responds, not the brain)

Dendrites

Branch-like structures on neurons that receive signals from other neurons and transmit them toward the cell body.

Soma (aka Cyton, Cell Body)

The cell body of a neuron, containing the nucleus and organelles, responsible for maintaining the cell's life and function.

Axon

The long, thin projection of a neuron that transmits electrical impulses away from the cell body towards other neurons or muscles, ends in terminal buttons

Myelin Sheath

fatty covering encasing around the axon and ids in accelerating neural impulses(protects and insulates the axon) (formed by gilial cells too)

Multiple Sclerosis

myelin sheaths deteriorates around neurons, interfering with neural transmission

Nodes of Ranvier

small gaps in the myelin sheath that expose the axon and facilitate the rapid transmission of electrical impulses through saltatory conduction.

Salutory Conduction

a process where electrical impulses jump between nodes of Ranvier, increasing the speed of signal transmission along myelinated axons.

Axon Terminal

Ends of the neuron

Terminal Buttons

(aka end buttons, terminal branches, synaptic knobs) structures at the axon terminal that release neurotransmitters into the synapse.

Synapse

space between the terminal buttons of one neuron and dendrites of the next neuron where neurotransmission occurs. (very tiny space)

Neural Transmission

The process by which signals are transmitted along neurons through electrical impulses and chemical neurotransmitters between synapses.

Resting Potential

The state of a neuron when it is not transmitting signals, characterized by a negative electrical charge inside the cell relative to the outside. (-70 millivolts, Polarized)

Threshold

The level of stimulation required to trigger an action potential in a neuron, indicating the point at which the neuron becomes sufficiently depolarized to fire.

Action Potential

When sufficiently stimulated (to threshold), a net flow of sodium ions into the cell causes a rapid change in potential across the membrane

electrical impulse that travels down the axon

All or none principle

states that once a neuron reaches threshold and fires an action potential, it will do so at full magnitude, or not at all, regardless of the strength of the stimulus.

Depolarization

neural firing creating a positive electrical charge (+30 millivolts) inside the neuron

Refractory period

a brief period where the neuron cannot fire again

Reuptake

the sending neuron recollects neurotransmitters(reusing them for future use after signal transmission)

Synaptic Vesicles

small, sac-like structures from the axon terminals that store and release neurotransmitters; open up for neurotransmitters to travel through the synapse from action potential

Electricity vs Chemical Transmission

• Electricity travels within the cell

• Chemicals(neurotransmitters) travel between cells in the synapse

Neurogenesis

growth of new neurons

Neurotransmitters

chemical messengers that transmit signals across synapses between neurons

Excitatory Neurotransmitter

a type of neurotransmitter that increases the likelihood of a neuron firing an action potential, promoting signal transmission; it excites the next cell into firing

Inhibitory Neurotransmitter

a type of neurotransmitter that decreases the likelihood of a neuron firing an action potential, reducing signal transmission; it inhibits the next cell from firing.

Glutamate

the primary excitatory neurotransmitter in the brain, involved in cognition, memory formation, and learning.

-Processing info throughout the cortex

-Memory in hippocampus

• W/ excess/deficit: triggers migraines, seizures

GABA(gamma aminobutryic acid)

the primary inhibitory neurotransmitter in the brain, crucial for regulating neuronal excitability and preventing excessive stimulation; associated with anxiety-related disorders

• W/ excess/deficit: internalizes when having seizures and can cause sleep problems

Acetylcholine(ACh)

a neurotransmitter that facilitates motor movement, as well as involved in learning and memory(etc.)

• W/ excess/deficit: lack causes Alzheimer’s, also involved in Myasthenia gravis(muscle weakness)

Dopamine

a neurotransmitter that plays a key role in reward, alertness, and motor control; stimulating to synthesize hormones; often linked to pleasure and mood regulation.

• Deficit - associated with Parkinson’s disease

• Excess - associated with schizophrenia

Endorphins

a neurotransmitter involved in pain perception and reduction; can be stimulated by exercise, stress, and pain, promotes a sense of euphoria

• Excess/Deficit - involved in addictions

Epinephrine (Adrenaline)

a neurotransmitter and hormone that plays a key role in the body's fight-or-flight response, increasing heart rate and blood flow to muscles. It is also involved in regulating blood sugar levels and energy metabolism.

Norepinephrine (Noradrenaline)

a neurotransmitter involved in arousal, alertness(heightened sensitivity) + sleep and dreams

• Excess/Deficit - lack associated depression

Serotonin

a neurotransmitter that regulates mood, appetite, sleep, sexual activity

• Lack is associated with depression

Substance P

a neurotransmitter involved with pain perception, lack of it is associated with lack of pain(perception)

Endocrine System

consists of glands that secrete chemical messengers called hormones throughout your body; controlled in the brain by the hypothalamus

Adrenaline

hormone activated during the fight or flight response in stressful situations, speeds up bodily processes

(it’s also a neurotransmitter as discussed earlier)

Leptin

hormone involved in weight regulation; suppresses hunger

Ghrelin

hormone that activates eating/increasing appetite or hunger

Melatonin

triggers sleep and wakefulness responses in the brain(regulates sleep cycle)

Oxytocin

promotes good feelings such as trust and bonding

Pineal Gland

located in the brain, secretes melatonin that helps regulate circadian rhythms and is associated with seasonal affective disorder

Hypothalamus

produces hormones that stimulate (releasing factors) or inhibit secretion of hormones by the pituitary

Pituitary Gland

produces stimulating hormones for other various glands in the body like growth, metabolism, reproduction; located in the brain

Thyroid Gland

gland in neck that produces thyroxine, which stimulates and maintains metabolic activities

Parathyroids

glands in neck that secretes hormones to maintain calcium ion levels in blood(for the functioning of neurons)

Adrenal Gland

glands atop kidneys, produces adrenaline/epinephrine

Pancreas

gland near the stomach that secretes the hormones insulin and glucagon, which regulate blood sugar that fuels all behavioral processes

Ovaries and Testes

gonads in females and males that produce hormones necessary for reproduction and development of secondary sex characteristics

Brain

an organ of soft nervous tissue contained in the skull of vertebrates, functioning as the coordinating center of sensation and intellectual and nervous activity

Hindbrain

located in the top of the spinal cord, controls biological functions needed for survival

• Includes the medulla, pons, and cerebellum

Medulla

• Controls blood pressure, heart rate, and breathing(digestion too)

• Reflexes - Swallowing, sneezing, vomiting

• Located above the spinal cord

• Aka medulla oblongata

Pons

• connects certain parts of the brain(ex the hindbrain midbrain forebrain, braintstem and cerebellum)

• Helps to coordinate movements(like facial expressions) and sleep and dreams

Brainstem

Connects brain to the spinal cord, includes the medulla, pons, and RAS

Cerebellum

controls balance and equilibrium

• coordinated sequences of movement and implicit memory(subconscious)

Midbrain

• integrates sensory info and muscle movement

• connects higher and lower portions of the brain

• relays info btw the ears + eyes

• Includes the RAS

Reticular Activating System (RAS)

• Network of nerve fibers involved in attention, arousal, and alertness

• aka reticular formation

• primarily in the midbrain but extends to hindbrain

Limbic System

• involved in emotion, motivation, learning, and memory

• includes the thalamus, hypothalamus, amygdala, hippocampus

Thalamus

• in the center of the brain

• receives sensory info and then sends it to the cortex for interpretation(smell is the only exception)

Hypothalamus

• right underneath the thalamus

• activation of sympathetic and parasympathetic + body temp

• facilitates Fight or Flight

• Feeding(signals/motivates to eat)

• Fornication(sexual motivation)

• endocrine system

Amygdala

• almond shaped structure

• anger, aggression, afraid(fear response)

• helps ingrain highly emotional memories

Hippocampus

• converts short term memory into long term memory + processing

• spatial relation memory

• Dysfunction causes alzheimer’s and anterograde amnesia

Forebrain

responsible for high-level functions like complex thought and sensory processing

Cerebral Cortex

thin wrinkled surface layer that covers the brain

• Full of neurons in which they grow and connect with other neurons(process known as pruning)

• Wrinkles - Fissures, enables more surface area

• center for higher order processes, like thinking, planning, judgement

• receives and processes sensory info and directs movement

Left Hemisphere

• facilitates sensory and motor functions of the right side of the body

• Consists of the frontal lobe, temporal lobe, parietal lobe, and the occipital lobe(4 lobes)

Right Hemisphere

• facilitates sensory and motor functions of the right side of the body

• Consists of the frontal lobe, temporal lobe, parietal lobe, and the occipital lobe(4 lobes)

Frontal Lobe