Cells, Tisues And Organs

Question 1

What is a cell?

Answer 1

A cell is the structural and functional unity of life in most living organisms

Question 2

What is a tissue?

Answer 2

A tissue is composed of a group of cells of common origin and similar structure all grouped together to carry out one specific function

Question 3

What is an organ?

Answer 3

An organ consists of a number of different tissues which form a part o the organism e.g eye, lung, heart, ear.

Question 4

What are the three embryonic tissues?

Answer 4

Mesoderm, ectoderm, endoderm

Question 5

What arises from the three Embryonic tissues?

Answer 5

4 adult tissues:
Muscular
Connective
Nerve
Epithelial

Question 6

Epithelial tissue definition

Answer 6

Epithelium is a tissue is composed of cells which line cavities and surfaces of structures throughout the body.

Question 7

General characteristics of epithelial cells

Answer 7

-tightly packed cells together
-held together by demosomes
-Small amounts of carbohydrate based cementing substance can be found in between them

Question 8

Functions of epithelia

Answer 8

-acts as a barrier between the inside and the outside of the body
-specialises into glands for secretion e.g sweat milk and hormones
-controls transport (in blood vessels, gut) and filtration in the kidneys
-specialises into sensory cells for smell and taste
- Cilia on the epithelium to help move substances over the epithelial surface

Question 9

TWO TYPES OF EPITHELIA

Answer 9

Covering- responsible for lining surfaces and structures
Glandular- Responsible for the synthesis and secretion of substances e.g glands

Question 10

Connective tissue definition:

Answer 10

Connective tissue consists of cells SUSPENDED in a MATRIX, the matrix can be anywhere from LIQUID to SOLID n consistency, the cells secrete the matrix THEMSELVES. Examples of connective tissues are cartilage, blood, bone, adipose tissue.
The matrix may consist of different propositions of collagen and elastin

Question 11

Common characteristics of connective tissues

Answer 11

-Cells spread WIDELY apart
- Cells suspended in MATRIX, secreted by the cells. With a consistency from liquid to solid and containing differing levels of elastin and collagen.

Question 12

Functions of connective tissue

Answer 12

• MAJOR supporting tissue of the body
• Creates SHEATH like bags over organs, SEPARATING them so they do not INTERFERE with each other’s activities
  -COVERS blood vessels for PROTECTION wherever they enter or exit an organ

Question 13

LOOSE CONNECTIVE TISSUE

Answer 13

Contains large amounts of GROUND SUBSTANCE, with cells scattered loosely all over suspended in the matrix.
Strengthened by loose protein fibres such as:
- Collagen, strengthens by forming a mesh work
-reticulin, supports the networks of collagen
-elastin, makes the tissue elastic

Question 14

Dense connective tissue and the difference between dense regular and dense irregular issue

Answer 14

Dense connective tissue contains LESS GROUND SUBSTANCE, with tightly packed collagen fibres (which create mesh work increasing the strength) therefore, Dense connective tissue is STRONGER than LOOSE connective tissue.
The difference between dense regular and dense irregular, is the way the collagen fibres are arranged. In dense regular collagen fibres are found in PARALLEL (TENDONS ) and in Irregular they are found IRREGULARLY ASSORTED/ARRANGED, this is found in TIGHT PACKAGINGS around organs.

Question 15

CARTILAGE

Answer 15

SPECIAL CONNECTIVE TISSUE
-Is STRONGER THAN dense and loose connective tissue
- has cells called CHONDROCYTES and these cells are found in spaces called LACUNAE
- Provides FLEXIBLE SUPPORT , and shock absorption
-found in between joints, vertebrae, nose, ear
- REDUCES FRICTION, between vertebrae and joints whilst performing activities

Question 16

BONE

Answer 16

SPECIAL CONNECTIVE TISSUE
- STRUCTURAL SUPPORT for the body
-PROTECTION FOR THE ORGANS SUCH AS CRANIUM FOR THE BRAIN
-PROVIDES SITE for MUSCLE ATTATCHMENT
-cells called OSTEOCYTES found in spaces called LACUNAE

Question 17

BLOOD

Answer 17

SPECIAL CONNECTIVE TISSUE
-Cells surrounded by a LIQUID extra-cellular matrix called PLASMA
- MAIN FUNCTION, TRANSPORT OF MATERIAL THROUGHOUT THE CELL

Question 18

MUSCULAR TISSUE

Answer 18

Consists of cells which can GENERATE a FORCE which causes CONTRACTIONS, bringing about movement.

Question 19

THREE TYPES OF MSUCULAR CELLS

Answer 19

SIRATED
CARDIAC
SMOOTH

Question 20

WHATS SIRATED MUSCLE

Answer 20

SIRATED cells, are LONG MUSCLE CELLS, which are PACKED with SPECIAL PROTEINS which contract when ATP is broken down.
-involved in locomotion, facial expressions and breathing
-can be conscious or unconscious

Question 21

Cardiac muscle cell

Answer 21

• forms the wall of the heart
• BRANCHED out, forming cell to cell contact with other cardiac muscle cells.
  -The contacts helps with signal transmition, helping during the heartbeat.
  -the role is to pump blood.
  -under involuntary movement.

Question 22

SMOOTH MUSCLE

Answer 22

-tapered at each end
-form the walls of the DIGESTIVE TRACT and BLOOD VESSELS

• responsible for INVOLINTARY MOVEMENT, e.g movement of digested food throughout the tract, or the dilation of arteries in hot weather.

Question 23

NERVOUS TISSUE

Answer 23

• consists of cells called NEURONES
• VARY in shape
• role is to TRANSMIT, information which bring about action, secretion, or other things to organs using ELECTROCHEMICAL SIGNALS