1. Biology and Behavior Chapter 3

2. Neural Communication
The body’s information system is built from billions of interconnected cells called neurons.

3. A nerve cell, or a neuron, consists of many different parts.
OBJECTIVE 3| Describe parts of a neuron and explain how its impulses are generated.

4. Parts of a Neuron Cell Body: Life support center of the neuron.
Dendrites: Branching extensions at the cell body. Receive messages from other neurons.
Axon: Long single extension of a neuron, covered with myelin sheath to insulate and speed up messages through neurons.
Axon: Terminals: Branched endings of an axon that transmit messages to other neurons.
Synapse: Space between the neurons

5. How does a Neuron fire? Resting Potential: slightly negative charge.
Reach the threshold when enough neurotransmitters reach dendrites.
Go into Action Potential.
All-or-none response.
Transfer of ions across axon’s membrane causes electrical charge.

6. It is an electrochemical process
Electrical inside the neuron
Chemical outside the neuron (in the synapse in the form of a neurotransmitter).
The firing is call Action Potential.

7. The All-or None Response
The idea that either the neuron fires or it does not- no part way firing.
Like a gun

8. Steps of Action Potential
Dendrites receive neurotransmitter from another neuron across the synapse.
Reached its threshold- then fires based on the all-or-none response.
Opens up a portal in axon, and lets in positive ions (Sodium) which mix with negative ions (Potassium) that is already inside the axon (thus Neurons at rest have a slightly negative charge).
The mixing of + and – ions causes an electrical charge that opens up the next portal (letting in more K) while closing the original portal.
Process continues down axon to the axon terminal.
Terminal buttons turns electrical charge into chemical (neurotransmitter) and shoots message to next neuron across the synapse.

9. Refractory Period & Pumps
Refractory Period: After a neuron fires an action potential it pauses for a short period to recharge itself to fire again.
Sodium-Potassium Pumps: Sodium-potassium pumps pump positive ions out from the inside of the neuron, making them ready for another action potential.

10. Action Potential Properties
All-or-None Response: When the depolarizing current exceeds the threshold, a neuron will fire. If the depolarizing current fails to exceed the threshold, a neuron will not fire.
Intensity of an action potential remains the same throughout the length of the axon.

11. Synapse
Synapse [SIN-aps] a junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron. This tiny gap is called the synaptic gap or cleft.
OBJECTIVE 4| Describe how nerve cells communicate. Synapse was coined by Lord Sherrington ( ) who inferred it through behavioral experiments. Cajal ( ) described the synapse based on his anatomical studies of the brain.

12. How Neurons Communicate

13. Neurotransmitters
Neurotransmitters (chemicals) released from the sending neuron travel across the synapse and bind to receptor sites on the receiving neuron, thereby influencing it to generate an action potential.

14. Types of Neurotransmitters

15. Acetylcholine (ACH) Deals with motor movement and memory.
Lack of ACH has been linked to Alzheimer’s disease and muscle paralysis

16. Dopamine Deals with attention, motor movement and alertness.
Lack of dopamine has been linked to Parkinson’s disease.
Too much has been linked to schizophrenia.

17. Serotonin Involved in mood control.
Lack of serotonin has been linked to clinical depression.

18. Endorphins
Involved in pain control.

19. Divisions of the Nervous System

20. The Nervous System
Nervous System: Consists of all the nerve cells. It is the body’s speedy, electrochemical communication system.
Central Nervous System (CNS): the brain and spinal cord.
Peripheral Nervous System (PNS): the sensory and motor neurons that connect the central nervous system (CNS) to the rest of the body.

21. Peripheral Nervous System
All nerves that are not encased in bone.
Everything but the brain and spinal cord.
Is divided into two categories….somatic and autonomic.

22. Somatic Nervous System
Controls voluntary muscle movement.

23. Autonomic Nervous System
Controls the automatic functions of the body.
Divided into two categories…the sympathetic and the parasympathetic

24. Autonomic Nervous System (ANS)
Sympathetic Nervous System: Division of the ANS that arouses the body, mobilizing its energy in stressful situations.
Parasympathetic Nervous System: Division of the ANS that calms the body, conserving its energy.

25. Sympathetic Nervous System
Fight or Flight Response.
Automatically accelerates heart rate, breathing, dilates pupils, slows down digestion.

26. Parasympathetic Nervous System
Automatically slows the body down after a stressful event.
Heart rate and breathing slow down, pupils constrict and digestion speeds up.

28. The Brain

29. Brain Structures Some scientists divide the brain up into three parts.
Hindbrain
Midbrain
Forebrain

30. Hindbrain Structures on top of our spinal cord.
Controls basic biological structures.
The brain in purple makes up the hindbrain.

31. Medulla Oblongata Located just above the spinal cord.
Involved in control of
blood pressure
heart rate
breathing.

32. Pons Located just above the medulla.
Connects hindbrain with midbrain and forebrain.
Involved in facial expressions, sleep, and attention

33. Cerebellum Located in the back of our head- means little brain.
Coordinates muscle movements.

34. Midbrain Coordinates simple movements with sensory information.
Contains the reticular activating system: arousal and ability to focus attention.
If damaged…Coma

35. Forebrain
Thalamus
Receives sensory information and sends them to appropriate areas of forebrain.
Like a switchboard.
Everything but smell.

36. Hypothalamus
The Hypothalamus lies below (hypo) the thalamus. It directs several maintenance activities like eating, drinking, body temperature, and control of emotions. It helps govern the endocrine system via the pituitary gland.

37. Hypothalamus Maybe most important structure in the brain.
Controls and regulates
Body temperature
Sexual Arousal
Hunger
Thirst
Endocrine System
The most powerful structure in the brain.

38. Limbic System EMOTIONAL CONTROL CENTER of the brain.
Made up of Hypothalamus, Amygdala and Hippocampus.

39. The Limbic System
The Limbic System is a doughnut-shaped system of neural structures at the border of the brainstem and cerebrum, associated with emotions such as fear, aggression and drives for food and sex. It includes the hippocampus, amygdala, and hypothalamus.
OBJECTIVE 13| Describe the structures and functions of the limbic system, and explain how one of these structures controls the pituitary gland.

40. The Limbic System

41. Amygdala Involved in how we process memory.
More involved in volatile emotions like fear & anger.

42. Hippocampus
Involved in the processing and storage of memories.

43. Cerebrum Largest part of the brain
Surface of brain called the: cerebral cortex

44. Areas of the Cerebral Cortex
Divided into 4 lobes
Frontal
Temporal
Parietal
Occipital

45. Frontal Lobes
Deals with planning, maintaining emotional control and abstract thought.
Contains Motor Cortex: sends signals to our body controlling muscle movements.
Contains Broca’s Area: responsible for controlling muscles that produce speech.
Damage to Broca’s Area is called Broca’s Aphasia: unable to make movements to talk. Contains Broca’s Area.

46. Motor and Sensory Cortexes

47. Parietal Lobes Located at the top of our head.
Contains the somato-sensory cortex.
Rest are association areas.

48. Temporal Lobes Process sound sensed by ears. Not lateralized.
Contains Wernicke’s area which interprets written and spoken speech.
Wernike's Aphasia: unable to understand language: the syntax and grammar

49. Occipital Lobes In the back of our head.
Handles visual input from eyes.
Right half of each retina goes to left occipital lobe and vice versa.
Contains Visual Cortex: interprets messages from our eyes into images we can understand.

50. The Corpus Callosum
Divides the 2 hemispheres.

51. Hemispheres Divided into to hemispheres.
Contralateral control: right controls left and vice versa.
In general,
Left Hemisphere: logic and sequential tasks.
Right Hemisphere: spatial and creative tasks.

52. Hemispheres Divided into a left and right hemisphere.
Contralateral controlled- left controls right side of body and vice versa.
Brain Lateralization.
Lefties are better at spatial and creative tasks.
Righties are better at logic.

53. Accidents
Phineas Gage Story
Personality changed after the accident.

54. Brain Plasticity
The idea that the brain, when damaged, will attempt to find news ways to reroute messages.
Children’s brains are more plastic than adults.

55. Lesions
Brain tumors also lesion brain tissue.

56. Ways to study the Brain Electroencephalogram (EEG)
Computerized Axial Tomography (CAT)
Magnetic Resonance Imaging (MRI)
Positron Emission Tomography (PET)
Functional MRI (fMRI)

57. Electroencephalogram
Detects brain waves through their electrical output.
Used mainly in sleep research.

58. PET Scan
PET (positron emission tomography) Scan is a visual display of brain activity that detects a radioactive form of glucose while the brain performs a given task.
Courtesy of National Brookhaven National Laboratories

59. Positron Emission Tomography
Measures how much glucose the brain uses.

60. MRI Scan
MRI (magnetic resonance imaging) uses magnetic fields and radio waves to produce computer-generated images that distinguish among different types of brain tissue.

61. Magnetic Resonance Imaging
More detailed picture of brain using magnetic field to knock electrons off axis.
Takes many still pictures and turns images into a movie like production.

62. Computerized Axial Tomography
function3D X-Ray of the brain.
Good for tumor locating

63. Functional MRI
Shows the tissue and the function of the brain

64. The Endocrine System A system of glands that secrete hormones.
Similar to nervous system, except hormones work a lot slower than neurotransmitters.
Hormones
Neurotransmitters

65. The Endocrine System
The Endocrine System is the body’s “slow” chemical communication system. Communication is carried out by hormones synthesized by a set of glands.
OBJECTIVE 10| Describe the nature and functions of the endocrine system and its interaction with the nervous system.

66. Hormones
Hormones are chemicals synthesized by the endocrine glands that are secreted in the bloodstream. Hormones affect the brain and many other tissues of the body.
For example, epinephrine (adrenaline) increases heart rate, blood pressure, blood sugar and feelings of excitement during emergency situations.

67. The Major Endocrine Glands

68. Pituitary Gland
Is called the “master gland.” The anterior pituitary lobe releases hormones that regulate other glands. The posterior lobe regulates water and salt balance.

69. Thyroid & Parathyroid Glands
Regulate metabolic and calcium rate.

70. Adrenal Glands
Adrenal glands consist of the adrenal medulla and the cortex. The medulla secretes hormones (epinephrine and norepinephrine) during stressful and emotional situations, while the adrenal cortex regulates salt and carbohydrate metabolism.

71. Gonads
Sex glands are located in different places in men and women. They regulate bodily development and maintain reproductive organs in adults.