1. Why could you compare the cell membrane to the gates of a stadium ?

2. HOW DO SUBSTANCES GET INTO and OUT OF THE CELL?
Before we start---
Passive diffusion page– fix the Oxygen with one circle to two circles—O2
Sodium page– Left side --add 4 more sodium (Na) to inside the cell
Active transport page– Left side- add one sodium (Na) to the inside

3. HOW DO SUBSTANCES GET INTO THE CELL?
The cell membrane is the gate:
Passive transport
Simple diffusion
Facilitated diffusion by a protein
Active Transport

4. Simple diffusion

7. Facilitated Diffusion with the help of proteins

10. Active Transport- needs energy

12. Diffusion---
Movement of a substance from an area of high concentration to lower concentration
Active transport--- Use of energy (ATP) to transport a substance from low to high concentration

13. Osmosis- movement of water from high to low through a membrane
Page 5

14. CYSTIC FIBROSIS By:  Dr. Barb Goodman The American Physiological Society, Education Office
Cystic fibrosis is an inherited disease that is relatively common in the U.S.  Cystic fibrosis affects multiple parts of the body including the pancreas, the sweat glands, and the lungs. 
When someone has cystic fibrosis, they often have lots of lung problems.  The cause of their lung problems is directly related to basic problems with diffusion and osmosis in the large airways of the lungs.

15. People without cystic fibrosis have a small layer of salt water in the large airways of their lungs. 
This layer of salt water is under the mucus layer which lines the airways. 
The mucus layer in the airways helps to clear dust and other inhaled particles from the lungs.
In people without cystic fibrosis, working cystic fibrosis proteins allow salt (chloride) to enter the mucus layer and water follows by osmosis.  The mucus layer is dilute and not very sticky.

16. In people with cystic fibrosis,
                                                                                                                                                                                                
non-working cystic fibrosis proteins
mean no salt (chloride) enters the space
and water doesn't either. 
The mucus layer is concentrated and very sticky.

17. People with cystic fibrosis have lung problems because:
    ~Proteins for diffusion of salt don't work.   (less diffusion)     ~Less salt means less water in the airways.               (less osmosis)
    ~ Less water in the airways means mucus layer is very sticky     ~Sticky mucus cannot be easily moved to clear particles from the lungs.     ~Sticky mucus traps bacteria and causes more lung             infections.

18. People with the abnormal protein develop cystic fibrosis
Genome.gov
Three DNA bases are deleted in the mutated sequence, resulting in the deletion of an amino acid (phenylalanine) from the CF  protein.
People with the abnormal protein develop cystic fibrosis

19. Biology Workbench

21. The Nerve Impulse

22. Fig. 2-12, p. 37 Figure 2.12: The blood-brain barrier.
Most large molecules and electrically charged molecules cannot cross from the blood to the brain. A few small, uncharged molecules such as O2 and CO2 cross easily; so can certain fat-soluble molecules. Active transport systems pump glucose and amino acids across the membrane.
Fig. 2-12, p. 37 22

23. The Cells of the Nervous System
Active transport is the protein mediated process by which useful chemicals are brought into the brain.
Glucose, hormones, amino acids, and vitamins are brought into the brain via active transport.

24. Figure 2.2: An electron micrograph of parts of a neuron from the cerebellum of a mouse.
The nucleus, membrane, and other structures are characteristic of most animal cells. The plasma membrane is the border of the neuron. Magnification approximately x 20,000. (Source: Micrograph courtesy of Dennis M. D. Landis)
Fig. 2-2, p. 31 24

25. The Cells of the Nervous System
All neurons have the following major components:
Dendrites.
Cell body.
Axon.
Presynaptic terminals.

26. The Nerve Impulse
The membrane is selectively permeable, allowing some chemicals to pass more freely than others.
Sodium, potassium, calcium, and chloride pass through channels in the membrane (what kind of diffusion?).

27.
The resting potential of a neuron refers to the state of the neuron prior to the sending of a nerve impulse.
The membrane of a neuron maintains an electrical gradient which is a difference in the electrical charge inside and outside of the cell.

28. At rest, the membrane maintains an electrical polarization or a difference in the electrical charge of two locations
the inside of the membrane is slightly negative with respect to the outside. (approximately -70 millivolts)

29. When the membrane is at rest:
Sodium channels are closed.
Potassium channels are partially closed allowing the slow passage of sodium.

30. In living cells nerve impulses are started by receptor cells.
Stimulus- food on a taste receptor
Biologymad.com

31. Other xamples– hair vibration of sound– pressure on skin
All or nothing law-

33. The Nerve Impulse
The sodium-potassium pump is a protein complex that continually pumps three sodium ions out of the cells while drawing two potassium ions into the cell.
helps to maintain the electrical gradient.

34. Differential permeability of the neuron membrane to Na+ and K+ ions
These ions can only cross the membrane via specific ion channel proteins that allow facilitated diffusion:
sodium pump
ion channel protein 34

35. Figure 2.14: Ion channels in the membrane of a neuron.
When a channel opens, it permits one kind of ion to cross the membrane. When it closes, it prevents passage of that ion.
Fig. 2-14, p. 40 35

36. The Nerve Impulse
A nerve impulse is the electrical message that is transmitted down the axon of a neuron.
The speed of nerve impulses ranges from approximately 1 m/s to 100 m/s.

37. The nerve impulse.
When a nerve impulse is transmitted along a neurone a wave of electrical activity passes along it
(NB: it is NOT a flow of electrons so it is not an electrical current)
This can be detected (e.g. by using oscilloscope with electrodes placed inside and outside the neurone) as a
transient change in electrical charge on the membrane surface –
this is called an ACTION POTENTIAL and is the basis of the nerve impulse.

38. Figure 2.13: Methods for recording activity of a neuron.
(a) Diagram of the apparatus and a sample recording. (b) A microelectrode and stained neurons magnified hundreds of times by a light microscope.
Fig. 2-13, p. 40 38

39. The Nerve Impulse
The resting potential remains stable until the neuron is stimulated.

40. The Nerve Impulse
An action potential is a rapid depolarization of the neuron.
Stimulation of the neuron past the threshold of excitation triggers a nerve impulse or action potential.

41. The Nerve Impulse
Voltage-activated channels are membrane channels whose permeabililty depends upon the voltage difference across the membrane.
Sodium channels are voltage activated channels.
When sodium channels are opened, positively charged sodium ions rush in and a subsequent nerve impulse occurs.

42. Action Potential

43. The Nerve Impulse
After an action potential occurs, sodium channels are quickly closed.
The neuron is returned to its resting state by the opening of potassium channels.

44. The Nerve Impulse
Local anesthetic drugs block sodium channels and therefore prevent action potentials from occurring.
Example: Novocain

45. Synapses between motor nerve and muscle
Motor end plate
Synapses between motor nerve and muscle 45

46. Neurones are connected together (normally via axons and dendrites) at synapses

48. This is not a physical junction, there is actually a small gap of approx 20 nm between the cells so there is no membrane continuity so nerve impulses cannot cross directly.
synaptic vesicles
synaptic bulb
pre-synaptic membrane
post-synaptic membrane 48

49. How nerve impulses are transmitted across a synapse by neurotransmitters

50. Transmission is mediated by chemicals called neurotransmitters
Stored in vesicles in the synaptic bulb
Several different types of neurotransmitters
Acetyl choline

52. The pathogenesis of Alzheimer’s disease (AD) has been linked to a deficiency in the brain neurotransmitter acetylcholine.
Subsequently, acetylcholinesterase inhibitors (AChEIs) were introduced for the symptomatic treatment of AD.

54. http://www. livinghistoryfarm. org/farminginthe70s/media/pests_0601

55. How do drugs cause their effects on the brain and behavior?
Drugs interfere with neurotransmission. More specifically, drugs of abuse produce feelings of pleasure by altering neurotransmission by neurons in the reward system that release the neurotransmitter dopamine.

56. Drugs
Nerve Gas

57. Methamphetamine alters dopamine neurotransmission in two ways.
1) enters the neuron by passing directly through nerve cell membranes.
2) carried to the nerve cell terminals by transporter molecules that normally carry dopamine or norepinephrine.
3) causes the release of neurotransmitter and also blocks the dopamine transporter from pumping dopamine back into the transmitting neuron..

58. Nicotine
acts at the cell body to increase the number of action potentials and number of vesicles released from a neuron,
Figure 3.2: Nicotine binds to specific receptors on the presynaptic neuron. When nicotine binds to receptors at the cell body, it excites the neuron so that it fires more action potentials (electrical signals) that move toward the synapse, causing more dopamine release (not shown in figure). When nicotine binds to nicotine receptors at the nerve terminal (shown above), the amount of dopamine released in response to an action potential is increased.

59. Drugs may also alter synaptic transmission by directly affecting the postsynaptic receptors.
Some drugs activate receptors, and others block them.

60. Cocaine 1) enters the brain,
2) blocks the dopamine transporter from pumping dopamine back into the transmitting neuron, flooding the synapse with dopamine.
3) This intensifies and prolongs the stimulation of receiving neurons in the brain's pleasure circuits, causing a cocaine "high."

63. http://science-education. nih