Chp 11: The Nervous System

11.1 The Nervous System: Receives, Integrates, and Responds to Information

The nervous system is responsible for receiving sensory input, integrating information, and coordinating responses. It is divided into several subdivisions, each with distinct functions.

• Key Point 1: The three main types of organs in the nervous system are the brain, spinal cord, and peripheral nerves. These organs are organized into basic subdivisions: the central nervous system (CNS) and the peripheral nervous system (PNS).

• Key Point 2: The nervous system is subdivided into 8 major areas, each with specific roles in processing and responding to information.

• Example: The CNS processes sensory information and initiates motor output, while the PNS transmits signals between the CNS and the rest of the body.

11.3 Neurons: The Structural Units of the Nervous System

Neurons are the fundamental cells of the nervous system, specialized for communication and signal transmission.

• Key Point 1: Neurons consist of several parts: dendrites (receive signals), cell body (contains nucleus), axon (transmits signals), and axon terminal (releases neurotransmitters).

• Key Point 2: The structure of a neuron determines its function in signal transmission and integration.

• Example: Multipolar neurons are the most common type in the body, especially in the CNS.

11.4 The Resting Membrane Potential and Differences in Ion Concentration and Permeability

The resting membrane potential is the electrical charge difference across the neuron's membrane, essential for nerve impulse transmission.

• Key Point 1: Electrical charge, voltage, membrane potential, current, and resistance are important terms in understanding neuron function.

• Key Point 2: Ion channels (chemically gated and voltage-gated) regulate the movement of ions, affecting membrane potential.

• Key Point 3: Sodium-potassium pumps and selective permeability of the membrane maintain the resting potential.

• Key Point 4: Depolarization occurs when the membrane potential becomes less negative; hyperpolarization is when it becomes more negative.

• Example: At rest, the neuron membrane is more permeable to potassium than sodium, resulting in a negative resting potential.

• Formula: (Membrane potential)

11.5 Graded Potentials

Graded potentials are changes in membrane potential that vary in size and are important for initiating action potentials.

• Key Point 1: Graded potentials occur in dendrites and cell bodies and can travel short distances (millimeters).

• Key Point 2: Graded potentials are essential for triggering action potentials when they reach the axon hillock.

• Example: Excitatory postsynaptic potentials (EPSPs) and inhibitory postsynaptic potentials (IPSPs) are types of graded potentials.

11.6 Action Potentials (AP)

Action potentials are rapid, all-or-none electrical impulses that travel along axons, enabling communication between neurons and muscles.

• Key Point 1: Action potentials travel over long distances (centimeters or more) and are essential for neural signaling.

• Key Point 2: The generation of an action potential involves depolarization, repolarization, and hyperpolarization phases.

• Formula: (Ionic current across membrane)

• Example: The opening of voltage-gated sodium channels initiates the action potential.

11.7 Synapses: Transmission of Signals Between Neurons

Synapses are specialized junctions where neurons communicate with other neurons or effector cells via neurotransmitters.

• Key Point 1: A synapse consists of a presynaptic neuron, synaptic cleft, and postsynaptic neuron.

• Key Point 2: Neurotransmitters are released from the presynaptic neuron and bind to receptors on the postsynaptic cell.

• Key Point 3: There are three main types of neurotransmitters: excitatory, inhibitory, and modulatory.

• Example: Acetylcholine is an excitatory neurotransmitter at neuromuscular junctions.

11.8 Postsynaptic Potentials: Excitatory or Inhibitory

Postsynaptic potentials determine whether a neuron will fire an action potential, depending on the balance of excitatory and inhibitory inputs.

• Key Point 1: Excitatory postsynaptic potentials (EPSPs) depolarize the membrane, while inhibitory postsynaptic potentials (IPSPs) hyperpolarize it.

• Key Point 2: Graded potentials can summate spatially and temporally to influence neuron firing.

• Example: Spatial summation occurs when multiple synapses are activated simultaneously.

11.9 The Effect of a Neurotransmitter Depends on the Receptor Protein

The action of a neurotransmitter is determined by the type of receptor it binds to on the postsynaptic cell.

• Key Point 1: Acetylcholine can excite skeletal muscle but inhibit cardiac muscle, depending on the receptor type.

• Key Point 2: Neurotransmitter effects are terminated by reuptake, enzymatic degradation, or diffusion away from the synapse.

• Example: The same neurotransmitter may have different effects in different tissues.

Chp 13: Classification of Neurons

13.1 Neurons: Classification

Neurons are classified based on their structure and function, which determines their role in the nervous system.

• Key Point 1: Most neurons in the body are multipolar, having multiple dendrites and a single axon.

• Key Point 2: Bipolar and unipolar neurons have distinct structural features and functions.

• Example: Sensory neurons are often unipolar, while motor neurons are typically multipolar.

Chp 16: The Endocrine System

16.1 The Endocrine System: One of the Body's Major Control Systems

The endocrine system regulates body functions through hormones, maintaining homeostasis and coordinating physiological processes.

• Key Point 1: Five important differences exist between neural and hormonal control, including speed, duration, and specificity.

• Key Point 2: The endocrine system uses chemical messengers (hormones) to regulate activities over longer periods.

• Example: Hormones like insulin and cortisol have widespread effects on metabolism and stress response.

16.2 The Chemical Structure of a Hormone: Hormones Act Through Second Messengers or by Activating Specific Genes

Hormones can be classified as amino acid-based or steroid-based, affecting target cells via different mechanisms.

• Key Point 1: Amino acid hormones act via second messengers; steroid hormones act by directly influencing gene expression.

• Key Point 2: Water-soluble hormones bind to membrane receptors; fat-soluble hormones cross the membrane to bind intracellular receptors.

• Example: Cortisol (a steroid hormone) regulates metabolism by altering gene transcription in target cells.

16.11 The Pancreas and Diabetes

The pancreas regulates blood glucose through the hormones insulin and glucagon, and dysfunction leads to diabetes mellitus.

• Key Point 1: Insulin lowers blood glucose; glucagon raises it, maintaining homeostasis.

• Key Point 2: Type 1 diabetes is characterized by lack of insulin production; Type 2 involves insulin resistance.

• Example: Adipose tissue is a risk factor for developing Type 2 diabetes due to its role in insulin resistance.

• Table:

  Feature	Type 1 Diabetes	Type 2 Diabetes
  Onset	Usually childhood	Usually adulthood
  Insulin Production	Absent	Present, but cells resistant
  Treatment	Insulin therapy	Lifestyle, medication

Chp 9: Muscular System

9.2A Skeletal Muscle: Made Up of Muscle Fibers, Nerves, Blood Vessels, and Connective Tissues

Skeletal muscle is composed of muscle fibers, nerves, blood vessels, and connective tissue, all essential for muscle function.

• Key Point 1: Connective tissue provides structure and support; nerves stimulate contraction; blood vessels supply nutrients and oxygen.

• Key Point 2: The organization of these tissues is necessary for coordinated muscle activity.

• Example: The endomysium surrounds individual muscle fibers, while the perimysium groups them into fascicles.

9.4 Structure and Function of the Sarcolemma, Sarcoplasmic Reticulum, and T-Tubules

The sarcolemma, sarcoplasmic reticulum, and T-tubules are specialized structures in muscle fibers that facilitate contraction.

• Key Point 1: The sarcolemma is the muscle cell membrane, involved in action potential propagation.

• Key Point 2: The sarcoplasmic reticulum stores and releases calcium ions, triggering contraction.

• Key Point 3: T-tubules transmit action potentials deep into the muscle fiber, ensuring coordinated contraction.

• Example: Calcium release from the sarcoplasmic reticulum initiates the sliding filament mechanism of contraction.

9.5 Temporal Summation and Motor Unit Recruitment: Allow Smooth, Graded Skeletal Muscle Contractions

Motor units and recruitment principles enable muscles to produce graded contractions, adjusting force as needed.

• Key Point 1: A motor unit consists of a motor neuron and all the muscle fibers it innervates.

• Key Point 2: Recruitment of additional motor units increases muscle force.

• Key Point 3: Temporal summation involves increasing the frequency of stimulation to produce sustained contractions.

• Example: During maximal tension, multiple motor units are recruited and stimulated rapidly.

9.6 ATP for Muscle Contraction: Produced Aerobically or Anaerobically

ATP is the energy source for muscle contraction, generated through aerobic and anaerobic pathways.

• Key Point 1: Aerobic metabolism uses oxygen to produce ATP; anaerobic metabolism does not require oxygen.

• Key Point 2: Different types of exercise utilize different energy sources.

• Formula:

• Example: Sprinting relies more on anaerobic metabolism, while endurance running uses aerobic pathways.

9.7 The Force, Velocity, and Duration of Skeletal Muscle Contractions Are Determined by a Variety of Factors

Muscle contraction characteristics depend on fiber type, recruitment, and exercise type.

• Key Point 1: Fast, intermediate, and slow twitch fibers differ in contraction speed and fatigue resistance.

• Key Point 2: Aerobic and resistance exercise have distinct effects on muscle and other body systems.

• Table:

  Fiber Type	Contraction Speed	Fatigue Resistance
  Slow Twitch	Slow	High
  Intermediate Twitch	Intermediate	Moderate
  Fast Twitch	Fast	Low

• Example: Resistance training increases muscle strength, while aerobic exercise improves endurance.

Additional info: Some details and terminology have been expanded for clarity and completeness based on standard Anatomy & Physiology curriculum.