Anatomy and Physiology lecture 2

Characteristics of Skeletal Muscle:
- Striated:
- Defined as having stripes (striations).
- Appearance due to the regular arrangement of actin and myosin filaments.
- Multinucleated:
- Each muscle fiber (cell) contains multiple nuclei.
- Muscles are unique because in the context of muscle tissue, one muscle fiber equals one muscle cell.
- Voluntary Control:
- Can be consciously controlled.
- Examples include muscles used in activities like weight lifting.
Muscle Fibers Explanation:
- Emphasized that the striations are key identifiers of skeletal muscle.
- A recurring theme in the course, particularly in Chapter 10 focused on muscle contractions.

Characteristics of Cardiac Muscle:
- Striated: Similar to skeletal muscle but with unique features.
- Intercalated Discs:
- Key cell junctions specific to cardiac muscle.
- Allow for synchronized contractions of the heart by connecting cells.
- Uninucleate (often):
- Typically has one nucleus but can occasionally have more than one.
- Involuntary Control:
- Not consciously controlled; heart contracts autonomously.
Importance of Intercalated Discs:
- Essential for the electrical conduction system of the heart, allowing rapid contraction.
- Attention drawn to specific wording for identification in study materials.

Characteristics of Smooth Muscle:
- No Striations:
- Appears smooth without stripes, leading to its name.
- Uninucleate:
- Typically has one nucleus per muscle fiber.
- Involuntary Control:
- Involved in automatic processes in the body;
  - Best exemplified in the digestive system where muscle contractions move food.
Examples of Smooth Muscle Function:
- Contraction of the esophagus and stomach.
- Strongest type of muscle; significant example is the uterus during childbirth.

Basic Components:
- Comprises neurons and glial cells (supporting cells).
Structure of Neurons:
- Neuron: Main functional unit.
- Cell Body: Contains the nucleus.
- Processes:
- Dendrites: Branch-like structures receiving signals.
- Axon: Long structure transmitting signals away from cell body.
- Myelin: Insulating layer around the axon, critical for rapid signal transmission.
Synaptic Transmission:
- Synaptic End Bulbs:
- Contain neurotransmitters for transmitting signals across synapses.
- Neurotransmitter Function:
- Released from one neuron and binds to receptors on another neuron’s dendrites.
Glial Cells:
- Also known as neuroglia, support and protect neurons.
- Represented visually as small dots in drawings.

Overview:
- Essential for communication and connectivity between cells.
- Three main types will be emphasized:

Definition: Very close attachment between cells, preventing leakage between them.
Example: Sertoli cells in the testes that facilitate sperm production by providing a protective barrier against the immune system.

Definition: Anchoring junctions that hold cells together.
Example: Intercalated discs in cardiac muscle, which stabilize the connection between adjacent muscle fibers during contraction.

Definition: Channels allowing direct communication between neighboring cells, facilitating the passage of small molecules and ions.
Example: In nervous tissue, where neurotransmitter molecules travel across synapses but may not always be picked up effectively.
SSRI Medications:
- Selective Serotonin Reuptake Inhibitors:
- Medications impacting serotonin neurotransmission by slowing down reuptake, thus enhancing mood regulation in certain individuals.

The outline of muscle and nerve tissues provides a foundation for understanding functioning in body systems.
Acknowledgement of the complexity and interactivity of these tissue types is essential for further study, particularly in upcoming chapters.