Biological Basis of Human Behavior

Study Notes

Biological Basis of Human Behavior

Human behavior is influenced by both nature (genetic inheritance) and nurture (environmental factors).
The nervous system and endocrine system serve distinct functions, with the nervous system primarily facilitating rapid communication through electrical signals, while the endocrine system manages longer-lasting regulatory functions through hormones.

Neurons and Glial Cells

Neurons are specialized cells that receive and transmit neural messages.
Glial cells support neurons by removing dead cells, nourishing them, insulating axons, and aiding in neural transmission.

Parts of Neurons

Dendrites are tree-like structures that receive incoming messages from other neurons.
Axons, which are long and slender, transmit impulses to other neurons via axon terminals.
Myelin is a fatty substance that insulates axons, enhancing the speed of neural impulse transmission.

Neural Impulse

Afferent neurons (sensory neurons) carry messages from sensory receptors to the central nervous system (CNS).
Efferent neurons (motor neurons) transmit messages from the CNS to muscles and glands.
Neural impulses are the electrochemical discharges of neurons, marked by various states:
- Polarization prepares a neuron for firing by creating a negative internal charge.
- Resting potential is typically about -70 millivolts.
- Depolarization reduces the resting potential toward zero.
- Action potential is the electrical impulse that propagates along an axon.

Synapse and Signal Transmission

A synapse is the junction between axon terminals of one neuron and dendrites of another.
The all-or-none principle states that a neuron fires with consistent strength when triggered.
The refractory period is a phase after firing when a neuron is less responsive to incoming signals.
Neurotransmitters are chemicals that facilitate communication between neurons.
Receptor sites on receiving neurons are specifically designed to bind with neurotransmitters.

Key Neurotransmitters

Acetylcholine (ACh): essential for muscle movement, memory, and cognition.
Dopamine: linked to pleasure perception, voluntary movement, learning, and implicated in disorders like Parkinson's and schizophrenia.
Norepinephrine: related to stress responses, with links to depression.
Serotonin: influences emotional states and sleep; deficiencies are associated with various mental health issues.
Gamma-aminobutyric acid (GABA): an inhibitory neurotransmitter that helps alleviate anxiety.
Endorphins: natural pain relievers in the brain, similar to morphine.

Nervous System Overview

The nervous system is divided into:
- Peripheral Nervous System (PNS): includes somatic and autonomic nervous systems.
  - Somatic system conveys messages to and from the CNS about external stimuli.
  - Autonomic system regulates involuntary functions (heart rate, respiration).
    - Sympathetic division prepares the body for 'fight or flight.'
    - Parasympathetic division conserves energy and restores the body post-stress.
Central Nervous System (CNS) consists of:
- Spinal Cord: transmits signals between the brain and the rest of the body.
- Spinal Reflex: response involving a direct pathway from sensory to motor neurons.
- Gray Matter: consists of neuron cell bodies involved in reflex actions.
- White Matter: contains axon bundles for communication between brain and body.

Brain and Cerebral Cortex

The cerebrum is the largest part of the brain and consists of two hemispheres.
The cerebral cortex is a wrinkled outer layer of the brain, involved in many higher brain functions.

Description

This quiz explores the biological foundations of human behavior, focusing on the roles of nature and nurture. Students will learn to differentiate between the functions of the Nervous System and the Endocrine System. Test your understanding of neurons and glial cells and their importance in the human body.