The Brain & Learning (CH 48)-Day 6

• Take notes on the following information!

RadialSymmetry

Deuterostome Development

Coelom

Pseudocoelom

Protostome Development

RadialSymmetry

Three Germ Layers;Bilateral Symmetry

Tissues

Multicellularity

Chordates

Echinoderms

Arthropods

Annelids Mollusks

Roundworms

Flatworms

Cnidarians

Sponges

Single-celled ancestor

• All animals except sponges have a nervous system.• What distinguishes nervous systems of different animal groups is how neurons are organized into circuits.

The animal kingdom

Organization of Nervous Systems

• The simplest animals with nervous systems, the cnidarians, have neurons arranged in nerve nets

Nerve net

Hydra (cnidarian)

Radialnerve

Nervering

Sea star (echinoderm)

The cnidarians, have neurons arranged in nerve nets

Sea stars have a nerve net in each arm connected by radial nerves to a central nerve ring

Eyespot

Brain

Nervecord

Transversenerve

Planarian (flatworm)

Brain

Ventralnerve cord

Segmentalganglion

Leech (annelid)

•simple cephalized animals, such as flatworms, •have a central nervous system (CNS)

Insect (arthropod) Chiton (mollusc)

Brain

Ventralnerve cord

Segmentalganglia

Anteriornerve ring

Longitudinalnerve cords

Ganglia

Annelids and arthropods have segmentally arranged clusters of neurons called ganglia.

These ganglia connect to the CNS and make up a peripheral nervous system (PNS).

Brain

Ganglia

Squid (mollusc)

Brain

Salamander (chordate)

Spinalcord(dorsalnervecord)

Sensoryganglion

In vertebrates, the central nervous system consists of a brain and dorsal spinal cord.

The PNS connects to the CNS.

SensorSensory input

Motor output

Integration

EffectorPeripheral nervous

system (PNS)Central nervous

system (CNS)

Information ProcessingNervous systems process information in three stages:

sensory input, integration, and motor output

• Sensory neurons transmit information from sensors that detect external stimuli and internal conditions

• Sensory information is sent to the CNS, where interneurons integrate the information

• Motor output leaves the CNS via motor neurons, which communicate with effector cells

• The three stages of information processing are illustrated in the knee-jerk reflex

Quadricepsmuscle

Cell body ofsensory neuron in dorsal rootganglion

Sensory neuron

Spinal cord(cross section)

Whitematter

Hamstringmuscle

Graymatter

Motor neuron

Interneuron

Dendrites

Cell body

Axon

InterneuronsSensory neuron Motor neuron

Neurons have a wide variety of shapes that reflect input and output interactions

Central nervoussystem (CNS) Peripheral nervous

system (PNS)Cranialnerves

GangliaoutsideCNS

Spinalnerves

Brain

Spinal cord

Dendrites

Cell body

Nucleus

Axon hillock Axon

Signaldirection

Presynaptic cellMyelin sheath

Synapticterminals

Synapse

Postsynaptic cell

Brain Cells are Neurons...

• cell body: contains nucleus & organelles• dendrites: receive incoming messages• axons: transmit messages away to other cells• myelin sheath: fatty insulation covering axon,

speeds up nerve impulses• synapse: junction between 2 neurons• neurotransmitter: chemical messengers sent

across synapse• Glia: cells that support neurons

– Eg. Schwann cells (forms myelin sheath)

Supporting Cells (Glia)

• Glia are essential for structural integrity of the nervous system and for functioning of neurons

• Types of glia: astrocytes, radial glia, oligodendrocytes, and Schwann cells

In the CNS, astrocytes provide structural support for neurons and regulate extracellular concentrations of ions and neurotransmitters

Green cells are the astrocytes.Blue stains the nucleus.

Axon Nodes ofRanvier

Schwanncell

Myelin sheathNucleus ofSchwann cell

Schwanncell

Nodes of Ranvier

Layers of myelinAxon

0.1 µm

Oligodendrocytes (in the CNS) and Schwann cells (in the PNS) form the myelin sheaths around axons of many vertebrate neurons.

Synapse….

• SYNAPSE: where a nerve cell touches another nerve cell (or muscle cell, etc).

• Brain uses synapse to send/receive signals

Central Nervous System• Brain and spinal cord• Cavities are filled with cerebrospinal fluid

– cushions and supplies nutrients and white blood cells. – Meninges are layers of connective tissue surrounding

the brain and spinal cord• White matter is myelinated; gray matter is not.

• Evolutionarily older structures in the brain regulate essential functions.

Cranial nerves originate in the brain and terminate mostly in organs of the head and upper body.

Spinal nerves originate in the spinal cord and extend to parts of the body below the head

The PNS has two functional components: the somatic and autonomic nervous systems

Peripheral Nervous System

Peripheral Nervous System

• Somatic nervous system (PNS):– Voluntary (conscious control)– Carries signals to skeletal muscles

• Autonomic nervous system (PNS) – Involuntary– Smooth and cardiac muscle, GI , cardio, excretory

and endocrine organs

Peripheralnervous system

Somaticnervoussystem

Autonomicnervoussystem

Sympatheticdivision

Parasympatheticdivision

Entericdivision

regulates the internal environment in an involuntary manner

carries signals to skeletal muscles

MOTOR DIVISION

Sympathetic:speeds up everything but digestion“fight or flight”adrenaline

Parasympathetic calms everything but digestion

PNS Divided into 2 Parts

• Sympathetic division– speeds up everything but digestion– “fight or flight”– adrenaline

• Parasympathetic division– calms everything but digestion

Embryonic brain regions

Forebrain

Midbrain

Telencephalon

Diencephalon

Mesencephalon

Hindbrain

Metencephalon

Myelencephalon

Diencephalon

Mesencephalon

Metencephalon

MyelencephalonMidbrain

Hindbrain

ForebrainTelencephalon

Spinal cord

Spinal cord

Embryo at one month Embryo at five weeks

Cerebral hemisphere

Medulla oblongata (part of brainstem)

Pituitarygland

Pineal gland(part of epithalamus)

Diencephalon:

Hypothalamus

Thalamus

Brainstem:

MidbrainPons

Medullaoblongata

Cerebellum

Central canalAdult

Pons (part of brainstem), cerebellum

Midbrain (part of brainstem)

Diencephalon (thalamus, hypothalamus, epithalamus)

Cerebrum (cerebral hemispheres; includes cerebralcortex, white matter, basal nuclei)

Brain structures present in adult

Embryonic Development of the Brain

All vertebrate brains develop from three embryonic regions: forebrain, midbrain, and hindbrain

Gray matter

Whitematter

Ventricles

BRAIN This white matter is distinguishable from gray matter, which consists mainly of dendrites, unmyelinated axons, and neuron cell bodies

Hindbrain

Pons

Medulla oblongata

Brainstem HOMEOSTASIS……breathing, heart activity,swallowing, vomiting, digestion; most ascending axons cross over here

BRAIN in the CNS has different parts.

Cerebellumcoordination and motor learning

Cerebrum

• Right and left hemispheres connected by corpus callosum

Cerebral cortex (gray matter) is the largest and most complex part of the mammalian brain

Cerebrum

Frontal lobe: speech, personality, motor cortexParietal lobe: somatosensory cortex, speech, taste, readingTemporal lobe: hearing, smellOccipital lobe: vision

Cerebrum

Language and Speech

• Brocca’s area – Frontal lobe– Patients with injury can understand language but

not speak• Wernicke’s area

– Temporal lobe– Patients with injury can speak but not

comprehend

Hypothalamus

Thalamus

Pituitary gland

Pineal gland

Hypothalamus: homeostasis by regulating hunger, thirst, temp., circadian rhythms

Thalamus: relay center

Diencephalon

Circadian Rhythms

• The hypothalamus also regulates circadian rhythms such as the sleep/wake cycle

• Animals usually have a biological clock, a pair of suprachiasmatic nuclei (SCN) in the hypothalamus

• Biological clocks usually require external cues to remain synchronized with environmental cycles

PET scan

Magnetic resonance images (MRI)

The limbic system: emotions and memory including olfaction

Memory and Learning

• The frontal lobes are a site of short-term memory

• They interact with the hippocampus and amygdala to consolidate long-term memory

• Many sensory and motor association areas of the cerebral cortex are involved in storing and retrieving words and images

Learning

• How does an organism learn about it’s environment? – Taxis: purposeful movement

• Toward stimulus = + taxis• Away from stimulus = - taxis

– Kinesis: random movement• Hoping for the best

Cognition

• Cognition means to know/learn and that you are being aware.– Environment + genes

• Metacognition = aware of how you learn– Learning Styles

Diagram of Brain• Tap into your creative side using pictures, sketches and words to form a collage in

each section of the brain to represent the functions of these lobes. • Frontal lobe -- Involved with planning, interpretation, emotions, personality,

deliberate movements, decision making, and turning thoughts into words.• Parietal lobe -- Perceives sensory inputs and and also associates these inputs with

past memories.• Temporal lobe -- Deals with the senses of smell and sound and also is responsible for

forming memories.• Occipital lobe -- Decodes images and objects that are seen in order to identify or

recognize them.• Cerebellum -- Regulates movement, balance and coordination.

– For example, in the frontal lobe section, drawings of people smiling, crying or communicating can be utilized.

– In the parietal lobe section, images representing the five senses can be pasted.