Lecture 5

Front 1

1.What are the four types of vertebrate tissue?

Back 1

Epithelium
Connective tissue
Muscle tissue
Nervous tissue

Front 2

2.Define epithelium.

Back 2

Membranous tissue of tightly connected cells from layers with relatively little ECM
Forms the outer layer and inner linings of organs and has various functions

Front 3

3.What is the difference between the apical and basal layers of an epithelial cell?

Back 3

Apical: upper side – faces lumen
Basal: lower side – attached to basal lamina (ECM)

Front 4

4.What are the terms used to describe epithelium layer types and cell shapes? Define each term.

Back 4

Simple: one layer
Stratified: multiple layers
Pseudostratified: one layer with nuclei at different levels
Transitional: multilayered, can expand/contract (urothelium only)
Squamous: flat, scale-like
Cuboidal: cubic, like squares
Columnar: rectangular
Ciliated vs. non-ciliated

Front 5

5.What does the structure of epithelium indicate about the tissue?

Back 5

Simple squamous: wide surface, thin layer, easy transmembrane mvmt across (filtration, osmosis, diffusion; blood vessel: gas exchange)
Simple columnar: absorption, protection (small intestine)
Stratified squamous: protective physical barrier (skin)
Ciliated, pseudostratified, columnar: filtering debris (trachea, fallopian tubes)

Front 6

6.Describe the type and function of epithelium in the following: small intestine, blood vessel, skin, trachea

Back 6

Small intestine: simple columnar (absorption, protection)
Blood vessel: simple, squamous (gas exchange)
Skin: stratified, squamous (physical, protective barrier)
Trachea: ciliated, pseudostratified, columnar (filtering debris)

Front 7

7.What are the major cell types of the gut epithelium & what are their functions?

Back 7

Absorptive cell: densely-packed microvilli (absorption and secretion of hydrolytic enzymes)
Goblet cell: secretes mucous (protective barrier)
Enteroendocrine cells: secrete serotonin and peptide hormones (regulate growth, proliferation, and digestive activities of gut & can influence other cells)
Paneth cell: role in innate immune system (secretes molecules that kill bacteria)

Front 8

8.What type of cell junctions do the gut, tracheal epithelium, and skin have? Why is each type of junction important for each tissue?

Back 8

Gut: tight junction (virtually impermeable layer – prevents infection)
Tracheal: tight junction (prevents dust/debris from entering)
Vascular: adjustable tight junction (allows fluid and gas exchange)
Epidermal: tight junctions (prevents entry of outside pathogens

Front 9

9.What would happen if tracheal epithelium lost their cilia?

Back 9

If tracheal epithelium were unciliated, the layer of mucus (created by the Goblet cells) carrying debris would not be moved out of the trachea

Front 10

10.What type of cell junctions do blood vessels have? Why not tight?

Back 10

Adjustable tight junctions: allow passage of fluid and gas
Oxygen and CO2 need to be able to diffuse between lungs and circulatory system

Front 11

11.Is barrier protection the only function of the skin? Explain your answer.

Back 11

The cornification of the skin also serves to provide structural integrity

Front 12

12.Define connective tissue.

Back 12

Tissue that supports, binds, or separates tissues or organs
Comprised of relatively few mesenchymal cells with abundant ECM
Cartilaginous, fatty, elastic, or hard (bone)

Front 13

13.What is the most common connective tissue cell type?

Back 13

Fibroblasts: dispersed in connective tissue through body
Serves to maintain structural integrity of many tissues

Front 14

14.Is the fibroblast completely specialized (i.e., terminally differentiated)?

Back 14

No, it can differentiate into other connective tissues cell types (bone, cartilage, fat, smooth muscle)
Can become terminally differentiated once it forms into a specialized cell type

Front 15

15.What type of connective tissue does cartilage form? What is the function of chondrocytes within cartilage? Why is this function so critical? What is the function of cartilage?

Back 15

Very dense connective tissue
Chondrocytes are the mature cells that make up the cellular matrix of the cartilage
Reduces friction between bones
Links bone to bone; support, movement
Facilitate fluid exchange through gelatinous layers of cartilage (necessary for healing injured cartilage)

Front 16

16.What type of connective tissue does bone form? What is the function of bone?

Back 16

Very dense connective tissue
Osteoblasts secrete matrix of bone; major cellular component of bone (develop from mesenchymal stem cells in bone periosteum and marrow)
Bone functions: provide internal support, protection, and organismal mobility

Front 17

17.List the major cell types of bone along with their function and the cell type they are derived from.

Back 17

Osteoblasts: secrete matrix of bone ; major component; develop from mesenchymal stem cells in bone periosteum and marrow
Osteocytes: maintain bone; develop from mesenchymal stem cells in bone periosteum and marrow
Osteoclasts: reabsorb bone tissue; derived from hematopoietic stem cells in bone marrow; dissolved bone
Osteoid: freshly formed layer of osteoblast

Front 18

18.What would happen if the balance between osteoblasts and osteoclasts were disrupted? (i.e., What would happen to bone if there were too many osteoblasts or too many osteoclasts?)

Back 18

Osteoblasts and osteoclasts have opposing functions, balancing each other out
Osteoblasts build bone and osteoclasts dissolve/absorb bone, and osteocytes regulate these functions
If more osteoblasts than osteoclasts, this would result in over-production of bone
If more osteoclasts than osteoblasts, this would result in a reduction in bone mass

Front 19

19.What type of connective tissue does adipose form? What is the function of adipose? What cell type are adipocytes derived from?

Back 19

Very loose connective tissue
Store very large amounts of triglycerides (fat) as a form of energy
Derived from immature fibroblast cells (mesenchymal stem cells)

Front 20

20.Define muscle tissue. How is actin and myosin important to muscle tissue?

Back 20

Contractile tissue composed of cells rich in filaments made of actin & myosin, which produce the motive force for contraction

Front 21

21.Describe the 4 types of muscle cells.

Back 21

Skeletal muscle: movements under voluntary control; highly elongated shape and striated (striped); orderly array of sarcomeres (contractile units)
Heart muscle: only found in heart walls; striated appearance, single nuclei (striated: has sarcomeres)
Smooth muscle: not striated (no sarcomeres); function varies from propelling food along gut to erecting hairs in response to cold or fear; involuntary movement
Myoepithelial cells: non-striated; lie in epithelia unlike all other muscle cells (derive from different tissue during development)

Front 22

22.Define nervous tissue. What cells make-up nervous tissue? What is its function?

Back 22

Main component of central nervous system and PNS (peripheral nervous system)
Made up of neurons (nerve cells) and neuroglia (non-neuronal cells that provide support for neuronal cells)
Functions: sensory input, control of muscles and glands, homeostasis, mental activity
Neurons have long axons (stem-like structures) that transmit electrical action potential signals that lead to the release of neurotransmitters at the nerve terminal

Front 23

23.What is a nerve?

Back 23

Enclosed, cable-like bundle of axons in the PNS surrounded by a layer of connective tissue

Front 24

24.What is myelin? And what is its function?

Back 24

Neurological cells wrapped around axons
Function: allows for rapid conduction of axon potentials along nerves by functioning as electrical insulation
Generated by neuroglial cells