A&P - Membranes, Muscle Tissue, & Nervous Tissue

Types of membranes

• Epithelial membranes

• Synovial membranes

Epithelial membranes

Thin, sheet-like structures composed of epithelium and underlying connective tissue, covering surfaces and lining body cavities

Types of epithelial membranes

• Serous

• Mucous

• Cutaneous

Serous membranes - Function(s)

• Lines body cavities that lack openings to the outside of the body

• Cells secrete watery, serous fluid to lubricate surfaces

• Consists of simple squamous epithelium and a single layer of areolar connective tissue

Type of epithelial membrane

Serous membranes - Location(s)

Forms inner linings of the thorax and abdominal cavities, and covers organs in those cavities

Type of epithelial membrane

Mucous membranes - Function(s)

• Lines body cavities and tubes that open to the outside of the body

• Consists of simple columnar epithelium overlying a layer of areolar connective tissue

• Goblet cells contained within the membrane that secretes mucus

Type of epithelial membrane

Mucous membranes - Location(s)

Lines: 

• Oral and nasal cavities

• Tubes of digestive, respiratory, urinary, and reproductive

Type of epithelial membrane

Cutaneous membranes - Function(s)

• Epidermis → Stratified squamous epithelium

• Dermis → Areolar connective tissue and mainly dense irregular epithelium

• Hypodermis → Adipose connective tissue

Consists of stratified squamous epithelium and dense irregular connective tissue

Type of epithelial membrane

Cutaneous membranes - Location(s)

AKA skin (found only on skin)

Type of epithelial membrane

Synovial membranes - Function(s)

Lines, surrounds, and lubricates joints by secreting synovial fluid

Composed mainly of connective tissue

Synovial membranes - Location(s)

• Joints of limbs (shoulder, elbow, wrist, knee, ankle, hip)

• Joints of the spine (cervical vertebrae and lumbar vertebrae)

Muscle fibers

Elongated cells in muscle tissue

May contain multiple nuclei

Muscle tissue - Function(s)

Movement, ability to contract, maintains posture, produces heat, pumps blood, peristalsis (movement of intestines)

Types of muscle tissue

• Skeletal

• Smooth

• Cardiac

Skeletal muscle tissue - Function(s)

Attached to bone and can be controlled by conscious (voluntary) effort

The cells are long and cylindrical, striated, have many nuclei, and contract from nervous impulses

Skeletal muscle tissue - Location(s)

Attached to bones, skin, and to some facial muscles

Smooth muscle tissue - Function(s)

Involuntary (unconscious) muscle movement

Lacks striations, is uninucleate, and consists of spindle-shaped cells

Smooth muscle tissue - Location(s)

Walls of internal organs, digestive tract, blood vessels, and urinary bladder

Cardiac muscle tissue - Function(s)

Involuntary muscle movement

Consists of branching muscle fibers/cells that are connected to each other with intercalated discs

Each muscle fiber has a single nucleus in each cell but appears to be striated

Cardiac muscle tissue - Location(s)

Only found in the heart

Nervous tissue - Function(s)

• Regulates and controls body functions

• Generates and transmits nerve impulses

• Supports, insulates, and protects impulse-generating neurons

Main component of the nervous system (brain, spinal cord, nerves)

Nervous tissue - Location(s)

• Central nervous system (brain and spinal cord)

• Peripheral nervous system

Neurons

Largest cells of the neurons, transmits neural impulses

Glial cells

Smaller, more abundant cells of the neurons

Acts as support for neurons

• Myelin sheaths of glial cells provide insulation for neurons

• Regulates neurotransmitter levels

• Maintains the environment

Striations

The visible bands/stripes on muscle fibers/cells that allow for powerful and efficient contractions essential for muscle functions

Intercalated discs

Specialized junctions unique to cardiac muscle tissue that connect adjacent heart cells to enable synchronized contraction (heartbeats)

% of muscle tissue in the body

• 40% of the body is skeletal muscle tissue

• ~10% of the body is smooth or cardiac muscle tissue

Skeletal muscle tissue

Smooth muscle tissue

Cardiac muscle tissue

Nervous tissue