Brain and behaviour dr vbk

Post on 12-May-2015

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The Brain

• The Human brain is composed of many

parts that work together to organize our

movements, create our thoughts, form

our emotions, and produce our

behaviors.• The brain is able to function effectively

because of the intricate system of

support and protection it receives from

other parts of the body.

THE BRAIN

• Brain is supported by the nutrients and oxygen carried by blood vessels and protected by the bones of the skull and three layers of membranes.

• Fluid surrounding brain acts as a shock absorber.

• Divided into three sections: the hindbrain,

the midbrain, and the forebrain.

The Brain: Our Control Center

• The Forebrain - located in the front of the head

• Thalamus relay station for sensory

stimulation

• Hypothalamus regulates body temperature,

the storage of nutrients, hunger, thirst, and

movement

• Limbic System controls learning, memory,

emotion, hunger, sex and aggression

• Cerebrum largest part of the brain about 70%

of weight.

• Surface is wrinkled with ridges and valleys

The Brain: Our Control Center

• The Hindbrain - located at the base of the skull

• Medulla controls vital functions such as heart rate, blood pressure, and breathing

• Pons regulates bodily movement, attention, sleep and alertness.

• Cerebellum controls balance and coordination.• The Midbrain - between the hindbrain and

forebrain

• Reticular Activating System (RAS) controls vision and hearing.

• Makes people alert

• alcohol reduce the activity of RAS

• screen out certain noises

Our Control Center continues…

• Cerebral Cortex outer layer of the brain

• where thinking takes place

• makes us unique

• concerned with memory, language,

emotions, complex motor function and

perception

• Corpus Callosum connects the two hemisphere of the brain

• aids in getting information from one side of

the brain to the other

Left Verse Right Hemisphere

• Left Hemisphere contains language function, logic, problem solving, and mathematical computation.

• Right Hemisphere concerned with imagination, art, feelings, and spatial relations.

• Both hemisphere of the brain are involved in most human activities and abilities.

Left Verse Right Hemisphere

`Left Verse Right Hemisphere

Neurons

• Sensory Neurons - nerve cells that carry

information received by the sense to the central

nervous system.

• Motor Neurons - are nerve cells that carry

information from the central nervous

system to the muscles and the glands and

influence their functioning.

Parts of the Neuron

Parts of the Neuron

• The cell body is a relatively large, egg-shaped structure that provides fuel, manufactures chemicals, and maintains the entire neuron in working order.

• Dendrites are branchlike extensions that arise from the cell body; they receive signals from other neurons, muscles, or sense organs and pass these signals to the cell body.

• The axon is a single threadlike structure that extends from, and carries signals away from, the cell body to neighboring neurons, organs, or muscles.

• Axons can be several feet long.

Parts of the Neuron contd.

• End Bulbs, which look like tiny bubbles, are located at the extreme ends of the axon’s branches. Each end bulb is like a miniature container that stores chemicals called neurotransmitters, which communicate with neighboring cells.

• The synapse is an infinitely small space (20-30 billionths of a meter) that exist between an end bulb and its adjacent body organ (heart), muscles

(head), or cell body.

• Myelin Sheath – insulates an axon & prevents

inference from electrical signals generated in adjacent axons.

Synapse – Neuronal communication

Neurotransmitters• Neurotransmitters refers to about a dozen different

chemicals that are made by neurons and then used for communication between neurons during the performance of mental or physical

activities.

• Excitatory – stimulating the firing of messages

If more exist; messages sent on their way• Inhibitory – slowing the transmission of neural

messages• • If more exist; messages slowed or stopped• Foundation of behaviors and mental processes• Messages are carried in both directions.• They are stored in sacs in the axon terminals

Neurotransmitters conts.

• Types of neurotransmitters:• • Acetylcholine: controls muscles, used by the

motor neurons of the spinal cord and stimulates skeletal muscles

• • Dopamine: controls motor behavior, deficiency in chemical plays a role in Parkinson disease, & increase causes schizophrenia.

• • Nor-adrenaline: prepares the body for action• • Serotonin: controls emotional arousal and sleep• • Endorphins: decreases the effects of pain during

great bodily stress, such as an accident.

Gun Analogy - Neurotransmitters

• Action Potential – neuron fires an impulse

• Firing threshold

• “all or none” – the point at which the gun will

• fire, no matter how slowly the trigger is pulled

• • The neuron fires its electrical signal

• Refractory period – the cell cannot fire again.

• Re-uptake - Any excess neurotransmitters left in

• the synapse is recollected

• Antagonist – drugs used to blocks the action of

• neurotransmitters

• Agonist – drugs used to mimic the action of

• neurotransmitters

The Spinal Cord

• The Spinal Cord extend from the brain down the

back

• Column of nerves about as thick as a thumb

• Protected by the bones of the spine

• Transmits messages between the brain and

the muscles and the glands throughout the

body• Spinal reflex is a simple, automatic response to

something

Brain Scan

• EEG (Electroencephalogram)

an amplified recording of the waves of electrical activity that sweep across the brain’s surface these waves are measured by electrodes placed on the scalp

CT (computed tomography) Scan

• a series of x-ray photographs taken from different angles and combined by computer into a composite representation of a slice through the body; also called CAT scan

MRI (magnetic resonance imaging)

• a technique that uses magnetic fields and radio waves to produce computer-generated images that distinguish among different types of soft tissue; allows us to see structures within the brain

PET (positron emission tomography) Scan

• a visual display of brain activity that detects where a radioactive form of glucose goes while the brain performs a given task

Endocrine System

• Hormones: stimulate growth & certain types of reactions (emotional & physiological)

• Pituitary Gland: below the hypothalamus, size of a pea

• Master gland (growth) – regulates the growth of muscles, bones, glands

{prolactin – milk; oxytocin –labor}

• Thyroid Gland: thyroxin converting food to energy – (metabolism)

• hypothyroidism – overweight;

• hyperthyroidism – excitability,• inability to sleep & weight loss

Endocrine System

• Adrenal Gland: over kidney; cortex secretes cortical steroids increase resistance to stress, promote muscles development; cause liver to

release stored sugar produce

• Adrenaline & noradrenaline; deals with stress

• Testes/Ovaries: produces testosterone, estrogen & progesterone

• • Mainly reproductive hormones