1. Nervous and Chemical Regulation
Nervous System- Chapter 35
Endocrine System- Chapter 39, Sections 1 and 2

2. Regulation An organism’s environment is always changing
An organism needs to respond to these changes
Responses need to be regulated and coordinated
Irritability- the ability to respond to changes in the environment
In complex organisms the nervous and endocrine systems control regulation

3. Regulation in Protists (Amoeba and Paramecium)
No true nervous system
Do move away from strong light and harmful chemicals
Move toward food
Cilia’s beating is controlled

4. Regulation in the Hydra
Has a nervous net which reaches all cells
No organized center
When 1 area is stimulated, the entire organism responds

5. Regulation in the Earthworm
Has a central nervous system
Includes “brain” connected to 2 ventral nerve cords which enlarge into ganglia in each segment
Ganglia- group of cell bodies and interneurons that relay and coordinate nerve impulses

6. Earthworm (continued)

7. Regulation in the Grasshopper
Similar to the earthworm
Has a “brain”, ganglia, ventral nerve cords
Has sense organs which are more developed- eyes, antennae, taste organs, sensitive to sound

8. Grasshopper (continued)

9. Mechanisms of Nervous Regulation
Nerve cells carry impulses (messages) throughout the organism
Receptors (sense organs) perceive changes in the environment
Message is sent from the receptor over a pathway of nerve cells to effector (gland or muscle)
Effector responds to change

10. Mechanisms of Nervous Regulation (continued)
Stimulus is the change in the environment which causes the receptor to send the message
Brain- a group of nerve cells which coordinate and control the nervous system (interneurons)

11. Structure of Neurons Nerve cell = neuron
Can send electrical and chemical impulses along the cell membrane

12. 3 Parts of a Neuron 1) Cell Body- contains the nucleus and organelles
2) Dendrite- short, highly branched fibers that receive the impulse
3) Axon- long, thin fiber that extends from the cell body and carries the impulse away from the cell
Axon or dendrite is called the nerve fiber
The impulse is carried across the synapse (space between them)

13. Diagram of Nerve Synapse

14. Types of Nerves
Nerves are bundles of axons and dendrites bound together (you already know this)
Sensory nerves (sensory neuron)- carry impulse from the receptor to the spinal cord and brain
Interneuron - transmits impulses between sensory and motor neurons (the brain and spinal cord)
Motor nerves (motor neuron)- carry the impulse from the brain and spinal cord to the effector
Mixed nerves have both sensory and motor

15. Types of Nerves

16. Pathway of Nervous System
Stimulus → Receptor → Impulse →
(touch hot) (skin) (sensory nerve)
Brain → Impulse → Effector
(motor nerve) (muscles pull hand
away)

17. Transmission at Synapses
The impulse must be carried over the gap (synapse)
Chemical neurotransmitters (acetylcholine and norepinephrine) are at the end of the axon
The neurotransmitters cross the gap and start the impulse in the next nerve cell

18. Diagram of Neurotransmitter

19. Drugs and the Nervous System
Certain drugs interfere with the nervous system
Paralysis can result from neurotransmitters not being able to cross the synapse (can lead to death)
Stimulants increase the amount of neurotransmitters
Depressants block neurotransmitters
LSD interferes with a neurotransmitter

20. Human Nervous System- Central Nervous System
Contains the brain and spinal cord
Controls most body activities
Skull and spinal column protect the brain and spinal cord
Meninges- are 3 tough membranes that also protect the brain and spinal cord
Cerebrospinal fluid (CSF) fills the space between the membranes and cushions against shock

21. Human Nervous System- Central Nervous System
YouTube - The Brain 25 Frontal Lobes and Behavior The Story of Phineas Gage 1

22. Brain Is very active, uses a lot of glucose Parts of the Brain
Thalamus- relay center between parts of the brain and spinal cord, receives sensory information
Hypothalamus- controls body temperature, blood pressure, sleep, emotions, endocrine system

23. Parts of the Brain (continued)
Pons- relay system linking spinal cord and brain
Brainstem- consists of:
pons, medulla oblongata, and midbrain
Cerebrum-
largest part
highly developed
divided into 2 halves called hemispheres
different areas are responsible for different functions (hearing, vision, thought, memory)

24. Parts of the Brain (continued)
Cerebellum-
Below and to the rear of the cerebrum
Works with the cerebrum to coordinate muscle movement and balance
Medulla Oblongata-
Controls many involuntary activities (breathing, heartbeat)

25. Spinal Cord Connects the brain and the PNS
Sensory impulses travel up the cord to the brain
Motor impulses travel down the cord to effectors
Controls certain reflexes
Involuntary, automatic responses to certain stimuli
Blinking, sneezing, knee-jerk
Reflex arc- pathway goes through the spinal cord, NOT the brain

26. Sense Receptors Eye- Ear- For hearing and balance
Gives humans most information
Light enters the eye and the image forms on the retina
Ear-
For hearing and balance
Vibrations in the air enter inner ear and impulses travel to brain

27. Sense Receptors (continued)
Skin-
Have specific skin receptors for pain, touch, cold, heat, pressure
Are distributed differently in different parts of the body
Taste-
Taste buds contact neurons
Certain taste buds are responsible for certain tastes

28. Sense Receptors (continued)
Smell-
Have olfactory cells in upper nasal cavity
Connected to brain through olfactory nerves

29. Disorders
Polio
Stroke
Meningitis
Cerebral palsy

30. Chemical Regulation- Endocrine System
Releases chemicals into the bloodstream to regulate homeostasis
Chemical reaches the proper organ and a response occurs
Chemicals produce a slower, longer-lasting response than the nervous system

31. Glands Organs which secrete substances
Exocrine- have ducts for secretions
Endocrine- are ductless, secretions go directly into the blood (hormones)

32. Hormones Are chemical messengers Target 1 specific area of the body
There are 2 types-
Protein type- too big to pass through cell membrane (insulin)
Steroid type- can pass through cell membrane (estrogen)

33. Hormones (continued)
Prostaglandins- hormones that do not enter the bloodstream
Work on blood pressure, heart rate and other areas

34. Hormone Regulation- Positive Feedback
One change causes a second change, which reinforces the first change
↑in chemical A ⇨ an ↑in chemical B which ⇨ a further ↑in chemical A

35. Negative Feedback
One change causes a second change which opposes the first change
↑in chemical A ⇨ ↑in chemical B which ⇨ ↓in chemical A
An example of negative feedback is the thermostat in your house
In organisms, this helps to maintain homeostasis

36. Mechanisms of Hormone Action
One Messenger Model
Steroid hormone enters a target cell (only the target cell will allow the hormone in)
The hormone will bind with a receptor protein in the cell
The hormone receptor complex will then bring about the change in the cell

37. Diagrams of Mechanisms of Hormone Action

38. Mechanisms of Hormone Action (continued)
Two Messenger Model
Protein (non-steroidal) hormone binds with a receptor on the cell membrane
This type of hormone can not enter the cell
Enzymes inside the cell are activated and the effect is produced

39. Human Endocrine System
May have hypersecretion (too much) of a hormone secreted
May have hyposecretion (too little) of a hormone secreted
Either one leads to disorders

40. Pituitary and Hypothalamus
Are in the brain
Hypothalamus links nervous and endocrine systems
Pituitary-
Controls other glands
Secretes many hormones
Growth hormone- controls growth
Hormones controlling development and release of eggs, milk production, reabsorption of water in the kidneys

41. Thyroid In the neck Secretes thyroxine which regulates metabolism
The release of thyroxine is controlled by a negative feedback mechanism

42. Parathyroid In the thyroid There are 4 parathyroid glands
Secrete parathyroid hormone which regulates calcium and phosphate levels in the blood

43. Goiter
A deficiency of iodine in the diet causes a malfunction in the thyroid

44. Adrenal On top of the kidneys Hormones help body deal with stress
Epinephrine-
secreted in response to sudden stress
Breathing, heart rate, sweating, blood pressure all increase

45. Adrenal (continued) Corticosteroids-
Cortisol- important in regulating the glucose level in the blood
Cortisone- decreases swelling
Aldosterone- maintains mineral balance in blood

46. Pancreas (Islets of Langerhans)
Both exocrine (digestive enzymes) and endocrine (insulin and glucagon)
Insulin-
Affects glucose metabolism
↑ movement of glucose into body cells
↑change of glucose to glycogen

47. Pancreas (continued) Glucagon-
↑ change of glycogen to glucose
↑ blood glucose levels
Diabetes- disease where the pancreas does not produce enough insulin and blood glucose levels are not controlled