[RAP0 21LAB] PRELIM: Lesson 5 Tissue Level

Tissue Level

• It is the second level of biological organization, following the cellular level and preceding the organ level.

• It is a group of similar cells working together to perform a specific function.

• In the human body, they are categorized into four main types.

4 Types of Tissues

• Epithelial Tissue

• Connective Tissue

• Muscle Tissue

• Nervous Tissue

Epithelial Tissue

• Covers body surfaces, lines cavities, and forms glands.

• Examples:

  • Skin (epidermis)

  • Lining of the digestive tract

  • Glandular tissue (sweat glands, salivary glands)

3 Examples of Epithelial Tissue

• Skin (epidermis)

• Lining of the digestive tract

• Glandular tissue (sweat glands, salivary glands)

6 Functions of Epithelial Tissue

• Protection – Shields underlying tissues from mechanical injury, pathogens, and dehydration.

• Absorption – Found in the digestive tract, where it absorbs nutrients.

• Secretion – Produces substances such as mucus, enzymes, and hormones (e.g., glandular epithelium).

• Excretion – Aids in removing waste products (e.g., kidney tubules).

• Filtration – Allows selective exchange of substances, such as in the kidneys.

• Sensation – Contains sensory receptors for touch, pressure, and temperature.

Protection

• Function of Epithelial Tissue

• Shields underlying tissues from mechanical injury, pathogens, and dehydration.

Absorption

• Function of Epithelial Tissue

• Found in the digestive tract, where it absorbs nutrients.

Secretion

• Function of Epithelial Tissue

• Produces substances such as mucus, enzymes, and hormones (e.g., glandular epithelium).

Excretion

• Function of Epithelial Tissue

• Aids in removing waste products (e.g., kidney tubules).

Filtration

• Function of Epithelial Tissue

• Allows selective exchange of substances, such as in the kidneys.

Sensation

• Function of Epithelial Tissue

• Contains sensory receptors for touch, pressure, and temperature.

Types of Epithelial Tissue

• Based on Cell Layers:

  • Simple Epithelium

  • Stratified Epithelium

  • Pseudostratified Epithelium

• Based on Cell Shape:

  • Squamous

  • Cuboidal

  • Columnar

Simple Epithelium

• Type of Epithelial Tissue Based on Cell Layers

• (Single layer of cells, found in areas involved in absorption, secretion, and filtration).

Stratified Epithelium

• Type of Epithelial Tissue Based on Cell Layers

• (Multiple layers of cells, providing protection in high-friction areas).

Pseudostratified Epithelium

• Type of Epithelial Tissue Based on Cell Layers

• (Appears stratified but consists of a single layer with varying cell heights).

Squamous

• Type of Epithelial Tissue Based on Cell Shape

• (Flat, thin cells, e.g., lung alveoli for gas exchange).

Cuboidal

• Type of Epithelial Tissue Based on Cell Shape

• (Cube-shaped cells, e.g., kidney tubules for absorption and secretion).

Columnar

• Type of Epithelial Tissue Based on Cell Shape

• (Tall, rectangular cells, e.g., lining of intestines for absorption).

Ciliated, Glandular, and Transitional Epithelium

3 Specialized Epithelial Tissue

Ciliated Epithelium

• Specialized Epithelial Tissue

• Contains cilia for movement of substances

• (e.g., respiratory tract)

Glandular Epithelium

• Specialized Epithelial Tissue

• Produces and secretes substances

• (e.g., sweat and salivary glands).

Transitional Epithelium

• Specialized Epithelial Tissue

• Found in the urinary bladder, allowing stretching.

Connective Tissue

• It is one of the four primary tissue types in the body (along with epithelial, muscle, and nervous tissue).

• It provides structural and metabolic support, connects different tissues, and plays a role in immune defense.

6 Functions of Connective Tissue

• Support – Forms the framework for organs and the body (e.g., bones and cartilage)

• Binding – Connects different tissues (e.g., tendons connect muscles to bones).

• Protection – Cushions and protects organs (e.g., adipose tissue).

• Storage – Stores energy (e.g., fat) and minerals (e.g., calcium in bones)

• Transport – Blood, a connective tissue, transports oxygen, nutrients, and waste.

• Immunity – White blood cells in connective tissue help fight infections.

Support

• Function of Connective Tissue

• Forms the framework for organs and the body

• (e.g., bones and cartilage).

Binding

• Function of Connective Tissue

• Connects different tissues (e.g., tendons connect muscles to bones).

Protection

• Function of Connective Tissue

• Cushions and protects organs

• (e.g., adipose tissue).

Storage

• Function of Connective Tissue

• Stores energy (e.g., fat) and minerals (e.g., calcium in bones)

Transport

• Function of Connective Tissue

• Blood, a connective tissue, transports oxygen, nutrients, and waste

Immunity

• Function of Connective Tissue

• White blood cells in connective tissue help fight infections.

Loose and Dense Connective Tissue

Types of Connective Tissue

Loose Connective Tissue

• Areolar Tissue: Cushions and holds organs in place (found under the skin).

• Adipose Tissue: Stores fat, insulates, and protects organs.

• Reticular Tissue: Forms a supportive framework for soft organs (e.g., spleen, lymph nodes).

Areolar Tissue

• Type of Loose Connective Tissue

• Cushions and holds organs in place (found under the skin).

Adipose Tissue

• Type of Loose Connective Tissue

• Stores fat, insulates, and protects organs.

Reticular Tissue

• Type of Loose Connective Tissue

• Forms a supportive framework for soft organs

• (e.g., spleen, lymph nodes)

Dense Connective Tissue

• Dense Regular: Strong, parallel fibers (e.g., tendons, ligaments).

• Dense Irregular: Randomly arranged fibers providing strength (e.g., dermis of the skin).

• Elastic Tissue: Contains elastin for flexibility (e.g., walls of arteries)

Dense Regular

• Type of Dense Connective Tissue

• Strong, parallel fibers

• (e.g., tendons, ligaments).

Dense Irregular

• Type of Dense Connective Tissue

• Randomly arranged fibers providing strength

• (e.g., dermis of the skin).

Elastic Tissue

• Type of Dense Connective Tissue

• Contains elastin for flexibility

• (e.g., walls of arteries)

Specialized Connective Tissue

Cartilage:

• Hyaline Cartilage: Found in joints, nose, and trachea.

• Elastic Cartilage: Provides flexibility (e.g., ear, epiglottis).

• Fibrocartilage: Strongest type, found in intervertebral discs.

Cartilage

• Specialized Connective Tissue

• Flexible support, lacks blood vessels

Hyaline Cartilage

• Specialized Connective Tissue; Cartilage

• Found in joints, nose, and trachea.

Elastic Cartilage

• Specialized Connective Tissue; Cartilage

• Provides flexibility (e.g., ear, epiglottis).

Fibrocartilage

• Specialized Connective Tissue; Cartilage

• Strongest type, found in intervertebral discs.

3 Types of Muscle Tissue

• Skeletal Muscle

• Cardiac Muscle

• Smooth Muscle

Skeletal Muscle

• Type of Muscle Tissue

• Voluntary (under conscious control)

• Striated (striped appearance under a microscope)

• Multinucleated cells

• Functions: Movement of the body, posture maintenance, and heat production

Cardiac Muscle

• Type of Muscle Tissue

• Involuntary (not under conscious control)

• Striated, but with intercalated discs for synchronized contraction

• Found only in the heart

• Functions: Pumping blood throughout the body

Smooth Muscle

• Type of Muscle Tissue

• Involuntary

• Non-striated (appears smooth under a microscope)

• Found in walls of hollow organs (e.g., intestines, blood vessels, uterus)

• Functions: Regulating organ function, controlling blood flow, and facilitating digestion

Function of Muscle Tissue

• Movement (body movement, heart contraction, peristalsis in digestion)

• Stability and posture

• Heat generation

• Protection of internal organs

Characteristics of Nervous Tissue

• Highly specialized cells: Nervous tissue is composed of neurons (nerve cells) and neuroglia (supporting cells).

• Excitability and conductivity: Neurons generate and transmit electrical impulses.

• Communication: Nervous tissue facilitates rapid communication between different parts of the body.

• Limited regeneration: Neurons have a very limited ability to regenerate, but neuroglia can divide and support neural function.

Highly specialized cells

• Characteristics of Nervous Tissue

• Nervous tissue is composed of neurons (nerve cells) and neuroglia (supporting cells).

Excitability and conductivity

• Characteristics of Nervous Tissue

• Neurons generate and transmit electrical impulses.

Communication

• Characteristics of Nervous Tissue

• Nervous tissue facilitates rapid communication between different parts of the body.

Limited regeneration

• Characteristics of Nervous Tissue

• Neurons have a very limited ability to regenerate, but neuroglia can divide and support neural function.

Components of Nervous Tissue

• Neurons (Nerve Cells)

• Neuroglia (Glial Cells)

Neurons (Nerve Cells)

• Components of Nervous Tissue

• Functional units of the nervous system.

• Transmit electrical and chemical signals.

Components of Neurons (Nerve Cells)

• Cell body (soma): Contains the nucleus and organelles.

• Dendrites: Receive signals from other neurons.

• Axon: Transmits impulses away from the cell body.

• Synaptic terminals: Release neurotransmitters to communicate with other cells.

Cell body (soma)

• Components of Neurons (Nerve Cells)

• Contains the nucleus and organelles.

Dendrites

• Components of Neurons (Nerve Cells)

• Receive signals from other neurons.

Axon

• Components of Neurons (Nerve Cells)

• Transmits impulses away from the cell body.

Synaptic terminals

• Components of Neurons (Nerve Cells)

• Release neurotransmitters to communicate with other cells

Neuroglia (Glial Cells)

• Components of Nervous Tissue

• Support, protect, and nourish neurons.

4 Types of Neuroglia (Glial Cells)

• Astrocytes: Maintain the blood-brain barrier and provide structural support.

• Microglia: Act as immune cells in the nervous system.

• Oligodendrocytes (CNS) and Schwann cells (PNS): Form the myelin sheath, which speeds up nerve impulses.

• Ependymal cells: Line the ventricles of the brain and spinal cord, producing cerebrospinal fluid (CSF).

Astrocytes

• Type of Neuroglia (Glial Cells)

• Maintain the blood-brain barrier and provide structural support.

Microglia

• Type of Neuroglia (Glial Cells)

• Act as immune cells in the nervous system.

Oligodendrocytes (CNS) and Schwann cells (PNS)

• Type of Neuroglia (Glial Cells)

• Form the myelin sheath, which speeds up nerve impulses.

Ependymal cells

• Type of Neuroglia (Glial Cells)

• Line the ventricles of the brain and spinal cord, producing cerebrospinal fluid (CSF)

Functions of Nervous System

• Sensory input: Detects environmental changes (e.g., touch, temperature, pain).

• Integration: Processes and interprets sensory data.

• Motor output: Sends signals to muscles and glands to produce responses.

• Homeostasis: Regulates body functions to maintain balance.

• Higher cognitive functions: Responsible for thinking, memory, and emotions.

Sensory input

• Function of Nervous System

• Detects environmental changes

• (e.g., touch, temperature, pain)

Integration

• Function of Nervous System

• Processes and interprets sensory data

Motor output

• Function of Nervous System

• Sends signals to muscles and glands to produce responses.

Homeostasis

• Function of Nervous System

• Regulates body functions to maintain balance.

Higher cognitive functions

• Function of Nervous System

• Responsible for thinking, memory, and emotions.

Brain; Spinal cord; Peripheral nerves

Location of Nervous System

organs; organ system

Tissues combine to form ___, which then function together in ___ to maintain homeostasis in the body.