Lecture 3: Connective Tissue and Integument
Reading: M&O Ch 4, 5
15. Compare and contrast the roles of individual cell types and fiber types within connective tissue.
16. Classify the different types of connective tissues based on distinguishing structural characteristics.
17. Describe functions of each type of connective tissue in the human body and correlate function with
structure for each tissue type.
18. Describe locations in the body where each type of connective tissue can be found.
19. Describe the structure and function of mucous, serous, cutaneous and synovial membranes.
20. Identify the locations in the body where each type of membrane can be found.
21. Identify and describe the structure and function of all layers of the epidermis, clearly indicating which
are found in thin skin and which are found in thick skin..
22. Describe the specific function of each dermal layer and relate that function to the skin’s overall functions.
23. Identify and describe the functions of the following epidermal structures: Hair follicles, sebaceous
glands, eccrine sweat glands, apocrine sweat glands
Connective tissue
Connective tissue contains cells in a matrix of fibers and ground substance. It is the body’s “stuffing”...it fills in all the spaces. Basic
characteristics of CT include:
1.
2.
3.
4.
5.
6.
Connecting or supporting
Usually highly vascular (except for cartilage, which is avascular)
Cells are far apart, with lots of extracellular materials
No free surfaces! This is because connective tissues CONNECT different layers.
May or may not be regenerative (or proliferative).
VERY DIVERSE
Types of cells (lots of variety!) can include:
1.
2.
3.
4.
5.
6.
Mesenchymal cells- undifferentiated precursors of all CT cells
Fibroblasts- fiber builders
Adipocytes- stores fat
Macrophages- phagocytize debris
Mast cells- produce histamine and heparin, causing inflammation
Other immune cells, like B cells and plasma cells
Fibers (secreted by fibroblasts)
1. Fibers determine the material properties of the tissue. This includes strength, brittleness, elasticity, etc.
2. 3 primary fiber types:
A. Reticular fibers: thin little strands of collagen that form a delicate, thin meshwork that is yielding. Found in solid structures
like lymph nodes.
B. Collagen fibers: twisted strands of collagen that form rope-like cords. They are incredibly strong (stronger than steel, which
breaks first, when compared with these fibers!) and do not stretch.
C. Elastic fibers: very stretchy fibers made of the protein elastin
3. The proportion of these fibers will determine the qualities of the tissue.
Ground substance
This is everything BUT the cells and the fibers. If you combine ground substance and fibers, you get the “matrix”. Ground substance
includes:
1. Water (in varying amounts)
2. Solutes (secreted by fibroblasts)
A. Proteoglycans and glycosaminoglycans, which are exceedingly hydrophilic. This keeps CT moist and hydrated.
B. Salts and ions can be crystallized or dissolved.
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Classifying CT
Combine these in different ways and get GRAND diversity of CT types.
• loose CT
• special CT
• areolar
• dense CT
• CT proper
• reticular
• dense regular CT
• structural CT
• adipose
• dense irregular CT
• hematopoetic CT
Membranes
Compound structures that line or cover organs, surfaces, or cavities, made of both ET and CT.
1. Mucous membranes
A. Structure
i. Epithelial tissue (varying types) bound to underlying connective tissue layer called the lamina propria.
ii. Two layers are linked by the basement membrane.
iii. Epithelial cells are often interspersed with goblet cells (single celled mucus-making glands).
B. Function(s)
i. Provide protection from external environment
ii. Allow absorption of goodies from external environment
iii. Enable secretion of substances from the internal environment into the external environment (like mucus!)
C. Location
i. Line internal spaces that open to the external environment.
2. Serous membranes
A. Structure
i. Simple squamous epithelium (called mesothelium) bound to a very thin layer of loose CT (areolar)
ii. ET and CT are linked by the basement membrane.
iii. Serous membranes are double layered membranes...
iv. Layer closest to organ (covering the organ) is the visceral layer
v. Layer lining the cavity is the perietal layer
Image from http://en.wikipedia.org/wiki/File:Serous_organ_invagination.gif
Copyright licensed under CC-BY-SA-3.0-MIGRATED by Serephine at en.wikipedia
B. Function(s)
i. Epithelial layer secretes serous fluid to reduce friction between organs and body walls
C. Location
i. Lining cavities and covering organs
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Functions of the integumentary system
1.
2.
3.
4.
Protection from abrasion, UV radiation, pathogens, dessication
Vitamin D synthesis
Sensory information
Temperature regulation
Layers of the skin
1. Epidermis (Activity: Label fig 5.2 pg 121)
A. Stratum basale (germinativum): Divides to produce other layers...also includes melanocytes
B. Stratum spinosum: Maturing keratinocytes and melanocytes
C. Stratum granulosum: Cells become dense and start filling up with keratin (protein). Cell begins to die.
D. Stratum lucidum: Dead cells...keratin is in an intermediate stage and consists of a different protein.
i. This layer is lacking in thin skin.
E. Stratum corneum: Dead cells...very flattened and made up of 20-30 layers of dead cells tightly linked together. Functions as
a barrier.
2. Dermis
A. Papillary layer (superficial)
i. Areolar connective tissue
ii. Little inlets of dermis into epidermis; increases surface area for contact between epidermis and dermis, enabling better
connections.
B. Reticular layer (deep)
i. Dense irregular connective tissue
ii. The term “reticular” refers to the fact that essentially, the collagen fibers are a MESS.
Other structures in skin (epidermal!)
1. Hair follicles (only in thin skin!)
2. Exocrine glands (secretes substances into external surfaces)
A. Sebaceous glands (only in thin skin)
i. These glands produce SEBUM (an oily/waxy lipid) to keep skin and hair lubricated.
ii. When they get plugged, this causes acne. (See “clinical view” on pg 135 of text)
B. Sweat glands
i. Eccrine: Secretes clear sweat that functions in temperature control (thermoregulation), secretion of water and
electrolytes, and protection from pathogens (because of the acidic nature and chemicals). Found all over body in thin
skin.
ii. Apocrine: Secretes protein/fat filled substance that bacteria ingest, causing odor. Found in armpits, around nipples, in
the pubic and anal regions. Become active after puberty. Could function in communication.
C. Ceruminous glands: produce earwax!
Bio 6: Human Anatomy
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Spring 2014: Riggs
Lab 3: Connective Tissue and Integument
Reading: E Ch. 3, Ch. 10
Part 1: General Connective Tissues
Use the listed slides to find and identify the different types of connective tissue and the structures each contains. Draw what you see.
1. Areolar connective tissue (H 570, HB 3-1): loose connective tissue
A. collagen fibers
B. elastic fibers
C. fibroblasts
2. Skin – Hair Follicles (HI 3-1): dense irregular connective tissue
A. collagen fibers
B. fibroblasts
3. Muscle – Tendon Junction (HB 5-1): dense regular connective tissue
A. collagen fibers
4. Thyroid Gland (HO 2-1): adipose connective tissue
A. fat vacuole
B. adipocyte nucleus
Part 2: Integument
In the integument you will recognize epithelium (which type?), and connective tissue (which type?), but you will also see new
structures. Pay particular attention to how the relative abundance of different layers/ structures varies among different kinds of skin.
Keep asking yourself about the functional significance of these structural differences.
Draw each slide. Label all required structures. Also check out the skin model and identify the required structures on it.
Skin – Human Sole (HI 1-2)
1. Epidermis (which type of epithelial tissue???)
A. stratum corneum
B. stratum lucidum
C. stratum granulosum
D. stratum spinosum
E. stratum basale
2. Dermis
A. papillary layer (tissue type?)
B. reticular layer (tissue type?)
3. Hypodermis (subcutaneous layer)
A. connective tissue (which type???)
B. Eccrine sweat glands
Skin – Hair Follicles (HI 1-3)
1. Epidermis
A. stratum corneum
B. stratum granulosum
C. stratum spinosum
D. stratum basale
2. Dermis
A. papillary layer
B. reticular layer
3. Hypodermis (subcutaneous layer)
A. connective tissue (which type???)
4. Hair follicle
A. hair bulb
B. hair
C. Sebaceous gland
D. Arrector pili muscle
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External Brain 3: CT and Skin
15. Compare and contrast the roles of individual cell types and fiber types within connective tissue.
16. Classify the different types of connective tissues based on distinguishing structural characteristics.
17. Describe functions of each type of connective tissue in the human body and correlate function with
structure for each tissue type.
18. Describe locations in the body where each type of connective tissue can be found.
19. Describe the structure and function of mucous, serous, cutaneous and synovial membranes.
20. Identify the locations in the body where each type of membrane can be found.
21. Identify and describe the structure and function of all layers of the epidermis, clearly indicating which
are found in thin skin and which are found in thick skin..
22. Describe the specific function of each dermal layer and relate that function to the skin’s overall functions.
23. Identify and describe the functions of the following epidermal structures: Hair follicles, sebaceous
glands, eccrine sweat glands, apocrine sweat glands
Your Task
1. Label images or DRAW pictures that include ALL required lab structures.
2. Thick and thin skin have different structures. Relate the differences in structure to their different functions.
3. Explain why the histology of the epidermis is well suited for its functions.
4. Predict the fibers you’d find in the connective tissue in each of the following locations. Defend your answers.
A. Tip of nose
B. Tendons
5. Name and describe the serous membranes found within each of the major body cavities.
6. Create a concept map using the following terms related to connective tissues (CT). Include distinguishing characteristics in your
map. Where possible, identify the cells, ground substance, and fibers found in each type of CT.
• loose CT
• special CT
• areolar
• dense CT
• CT proper
• reticular
• dense regular CT
• structural CT
• adipose
• dense irregular CT
• hematopoetic CT
7. Why did we study integument and connective tissues on the same day?
8. What can you conclude if you see no apocrine sweat glands in a skin slide?
Bio 6: Human Anatomy
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Spring 2014: Riggs