Basic Genetics Phenotype – an organisms observable traits Genotype – the traits that an organism can pass on to its offspring through its genetic material

Basic Genetics Genes - basic unit of heredity in a living organism Genes are located on chromosomes –Threadlike structures in the nucleus of each cell Chromosomes occur in matched pairs Each species has a characteristic number of pairs of chromosomes in each body cell –Humans? The two genes (alleles) that control each trait are situated at the same locus, one on each chromosome of a particular pair.

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Basic Genetics Sex Chromosomes and Sex-linked Traits Sex chromosomes may not be matched pairs 2 types of sex chromosomes – carry different genes X Y Female mammals have 2 X chromosomes Male mammals have X and Y chromosomes Sex-linked traits – traits that are influenced by genes on the sex chromosomes Mostly controlled by X chromosome Y chromosome – small, few genes

Basic Genetics The Genetic Code and Gene Expression Several different kinds of genes Structural genes – contain information for the synthesis of a protein Proteins – long chains of AA’s Control cellular activity All cells of the body contain exactly the same structural genes Operator genes – control structural genes (gene expression) Function to determine whether each of its structural genes initiates the synthesis of a protein and at what rate * Major mechanism by which experience can interact with genes to influence development

Structure and Functions of Cells of the Nervous System Chapter 2 Mind and Brain

Central Nervous System: Brain behaviourThe primary function of the brain is behaviour. –Sensing –Perceiving –Cognition –Movement

Central Nervous System: Spinal Cord Primary relay between the external environment and the brain The same basic components –meninges –CSF –cells

Introduction The nervous system consists of 2 basic divisions: –The central nervous system – the brain and spinal cord –The peripheral nervous system – the part of the nervous system outside the brain and spinal cord, including the nerves attached to the brain and spinal cord

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Protecting the CNS Meninges, Ventricles, and CSF CNS - encased in bone and covered by three meninges Dura mater - tough outer membrane Arachnoid membrane - weblike Pia mater - adheres to CNS surface Cerebrospinal fluid (CSF) Fluid serves as a cushion

Protecting the Brain Physical protection Skull Meninges Cerebrospinal fluid (CSF) Chemical protection The blood-brain barrier – tightly-packed cells of blood vessel walls prevent entry of many molecules

Chapter Preview To understand how the nervous system controls behavior, we must first understand its parts – the cells that compose it Cells of the Nervous System –Neurons –Glial cells Communication Within a Neuron Communication Between Neurons

Introduction The brain is the organ that moves the muscles – Movement, or behavior, is the primary function of the nervous system – Sensory neuron – a neuron that detects changes in the external or internal environment and sends information about these changes to the central nervous system – Motor neuron – a neuron located within the central nervous system that controls the contraction of a muscle or the secretion of a gland – Interneuron – A neuron located entirely within the central nervous system

Cells of the Nervous System Neurons –Basic Structure –Soma – cell body of a neuron which contains the nucleus. Figure 2.1

Cells of the Nervous System Neurons –Basic Structure –Dendrite – branched, treelike structure attached to the soma; receives information from other neurons. Figure 2.1

Cells of the Nervous System Neurons –Basic Structure –Axon – long, thin, cylindrical structure that conveys information from the soma of a neuron to its terminal buttons. Figure 2.1

Cells of the Nervous System Neurons –Basic Structure –Terminal Button – bud at the end of a branch of an axon; forms synapses with another neuron Figure 2.1

Cells of the Nervous System Neurons –Basic Structure –Synapse – junction between the terminal button of an axon and the membrane of another neuron. –Neurotransmitter – a chemical that is released by a terminal button Figure 2.4

The Principal Parts: Together

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Cells of the Nervous System Neurons –Multipolar –Unipolar –Bipolar Glial cells –Various types –Provide a wide variety of supportive functions

Cells of the Nervous System –Types of Neurons Multipolar Neuron – neuron with one axon and many dendrites attached to its soma; most common type in CNS. Figure 2.1

Cells of the Nervous System Types of Neurons Bipolar Neuron – neuron with one axon and one dendrite attached it its soma. –sensory systems (vision and audition) Unipolar Neuron – neuron with one axon attached to its soma; the axon divides, with one branch receiving sensory information and the other sending the information into the central nervous system. –somatosensory system (touch, pain, etc) Figure 2.2

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