Tissues and Integumentary (Skin) System

Nestor T. Hilvano, M.D., M.P.H.(Images Copyright Discover Biology, 5th ed., Singh-Cundy and Cain,

Textbook, 2012.)

Learning Objectives 1. Describe the 4 main types of tissues, noting their

structures, locations, functions and examples.

2. Describe the functions of the different organ systems.

3. Differentiate the types of epithelial tissues as to structure, function, and give an example for each.

4. Compare and contrast the 3 types of muscles.

5. Describe the nervous tissues.

6. Discuss the two main layers of the skin, including it’s functions and appendages.

7. Discuss homeostasis and distinguish between negative and positive feedback.

Overview of Structure and Function of Organism

• ___ What is the study of structures or parts of the body? ___ of function? ___ study of tissues? a) histology b) anatomy c) microbiology d) anatomy

• ___ is a group of similar cells with a common function.

• ___ is made up of several (different types) tissues.

• ___ is composed of many organs that work together to perform life functions.

a) organ system b) organ c) tissues d) organism

Systems (Organ-System)– The digestive and respiratory systems

• Gather food and oxygen

– The circulatory system, aided by the lymphatic system• Transports the food and oxygen

– The immune system• Protects the body from infection and cancer

– The excretory system • Disposes of certain wastes

– The endocrine and nervous systems• Control body functions

– The integumentary system• Covers and protects the body

– The skeletal and muscular systems• Support and move the body

– The reproductive system • Perpetuates the species

4 Main (Fundamental) Types of Tissues

1. epithelial tissue

2. connective tissue

3. muscular tissue

4. nervous tissue

Epithelial Tissue• Covers the body and lines its

organs and body cavities• Common features/characteristics

of epithelium:

a) closely packed cells

b) lie on basement membrane

c) avascular d) can be derived from 3 germ layers (ectoderm, mesoderm, endoderm)

• Functions = protection, secretion, absorption, filtration, sensory receptor, excretion, lubrication.

Pseudostratified columnar

Types of Epithelial Tissues:•__ 1 layer of cells. •__ 2 or more layers of cells. •__ false layers of cells (false stratification).

a.Stratified epitheliumb.Pseudostratified epitheliumc.Simple epitheliumd.Transitional epithelium

Simple Epithelium • Simple squamous

- function: exchange of materials, diffusion, or

filtration

- example: endothelium of blood vessels, alveoli

of lungs

• Simple cuboidal

- function: absorption or secretion

- example: kidneys tubules (w/brush border= microvilli),

ducts of glands, thyroid follicles

• Simple columnar - function: absorption or secretion

- example: digestive (GIT) tracts (w/ goblet cells,

striated border= microvilli)

Exercises: What is the fingerlike projections of cell membrane that increases surface area for absorption?

a. cilia b. microvilli c. flagella d. gap junction

Stratified Squamous • Stratified squamous - several layers of cells, squamous (flat) superficial cells - function: protective barriers • Stratified squamous non-

keratinized- outermost squamous cells are alive, nucleated squamous cells; found in oral cavity, esophagus, vagina

• Stratifies squamous keratinized (cornified)- outermost cells are dead, non-nucleated cells, with keratins; found in epidermis of skin

Pseudostratified Columnar• Pseudostratified Columnar- false

layers of cells, with cilia on surface and goblet cells; protection, secretion, and absorption

• Found in respiratory passages like trachea, bronchi, bronchioles

Exercises: __ What are the hair-like structures that move in

a sweeping motion to remove (filter) inhaled particles along the respiratory tract?

__ What is responsible for mucous secretion to lubricate and help trap dust and foreign particles in the respiratory passages?

a. microvilli b. goblet cells c. cilia d. columnar cells

Connective Tissue• Common features/characteristics of C.T.: a) Few cells in an extracellular matrix

(solid, semi-solid)b) vascularc) matrix contains 3 C.T. fiber types

– Collagen fibers provide strength and flexibility (strong fibers)

– Elastic fibers stretch and snap back to their original length (recoil)

– Reticular fibers join connective tissue to adjacent tissues

• Fibroblast cells- secrete the C.T. matrix• Functions = mainly binds and supports

other tissues

Fig. 40-5c

Connective Tissue

Collagenous fiber

Looseconnectivetissue

Elastic fiber12

0 µ

m

Cartilage

Chondrocytes

10

0 µ

m

Chondroitinsulfate

Adiposetissue

Fat droplets

15

0 µ

m

White blood cells

55

µm

Plasma Red bloodcells

Blood

Nuclei

Fibrousconnectivetissue

30

µm

Osteon

Bone

Central canal

70

0 µ

m

Types of C.T.1. Loose C.T. 2. Dense C.T. 3. Adipose tissue 4. Cartilage 5. Bone6. Blood

Muscle Tissue • Elongated cells (muscle

fibers) stimulated to contract; 3 types1. skeletal muscle – striated, voluntary muscle; cylindrical shape 2. cardiac muscle – striated, involuntary muscle; cylindrical-branched shape3. smooth muscle – nonstriated, involuntary

muscle; spindle or fusiform shape

Nervous Tissue• Communication network –

senses stimuli and transmit nerve signals that help control body activities

• CNS (brain and spinal cord) and PNS (nerves and ganglia)

• Consists of neurons (nerve cells) and neuroglial (supporting) cells

• ___ What is the functional and structural unit of nervous system?

a. nerve fiber b. neuroglia c. ganglia d. neuron

Integument (Skin)• 2 main layers- Epidermis and

dermis• Epidermis- stratified squamous

keratinized; melanocytes protect from UV radiation

• Dermis- C.T., consists of: a) papillary layer (loose C.T.), and b) reticular (dermis proper) layer (DICT), w/c contain appendages (hair follicles, sweat glands, sebaceous (oil) glands, & arrector pili muscle), blood vessels, and nerves

• Subcutaneous tissue (hypodermis) - supporting tissue w/c binds the skin to underlying structures (muscles).

Figure 26.5

Homeostasis and Feedback Mechanism• Homeostasis - Stable internal

conditions regardless of external conditions= equilibrium

• Negative feedback - Body senses a change and activates mechanisms to reverse it (negates the change); important to maintain health (good + feedback).

ex: thermoregulation of the body

• Positive feedback - Self-amplifying change (in the same direction).

ex: fever (bad + feedback); increase

blood clotting to stop bleeding (good +

feedback)

Fig. 40-16Sweat glands secrete sweat, which evaporates, cooling the body.

Thermostat in hypothalamus activates cooling mechanisms.

Blood vessels in skin dilate: capillaries fill; heat radiates from skin.

Increased body temperature

Decreased body temperature

Thermostat in hypothalamus activates warming mechanisms.

Blood vessels in skin constrict, reducing heat loss.

Skeletal muscles contract; shivering generates heat.

Body temperature increases; thermostat

shuts off warming mechanisms.

Homeostasis: Internal temperature

of 36–38°C

Body temperature decreases; thermostat

shuts off cooling mechanisms.

Homework 1. Define terms: anatomy, physiology, histology; tissues; organs;

systems; epithelial tissue, connective tissues; muscular tissues; melanocytes, nervous tissues; homeostasis; negative feedback, and positive feedback.

2. Describe characteristics of epithelial tissues as to structural organization.

3. Describe simple squamous, simple cuboidal, simple columnar, stratified squamous, and pseudostratified columnar epithelium as to cell layer/s and function/s and give an example where these are located.

4. Describe the common features of connective tissues, connective tissue fibers, and types (forms) of connective tissues.

5. Describe the 3 types of muscle tissues.

6. Describe nervous tissues.

7. Discuss the 2 main layers of skin.

8. What is the importance of hypodermis.

9. Describe the skin appendages.

10. Discuss the negative feedback mechanism of thermoregulation by an example.