Structure and function of cells and tissues

Question 1

Define tissues, organs and organ systems

Answer 1

tissue - group of specialized cells and matrix all performing similar functions

organ - two or more different tissues performing a common function

organ system - collection of organs working together to produce a range of functions

Question 2

describe structural & functional principles of the 4 basic tissues

Answer 2

•Epithelia
Protect, secrete, absorb and filtrateIt is used as linings coverings

•Connective tissue
Binding tissues and support, protection, insulation and transport, also supports mechanical loadThe type of connective tissue is characterised by cells separated by a matrix containing fibres

•Muscle
Contract for movement

•Nervous
Detect and respond to stimuli by the action of electrical impulses

Question 3

Describe the construction of tissues – cells,

Answer 3

• tissues may just contain cells such as epithelium, but usually contain other materials most notable an extracellular matrix

Question 4

Describe the construction of tissues – cell-cell junctions

Answer 4

Cell - Cell junctions - hold together tissues, allow communication between cells, control permeability - 2 types

1) desmosomes. - link intermediate filament on the cytoskeleton - mostly found in skin - Strenghten tissue - attach to keratin
2) Adherens - initiate cell - cell contact and hold epithelium together - transport proteins inside actin filament

Question 5

describe the construction of tissues - gap junctions

Answer 5

Gap junctions - allow direct communication between cells with membrane to membrane contact - connects the cytoplasm of two cells, allowing molecules and electrical impulses to pass through a regulated gate
- important in conduction of the heart

Question 6

Tight junctions

Answer 6

stop molecules passing between cells by using a continuous section of contact

Question 7

does cardiac cardiac muscles have cell - cell junctions

Answer 7

cardiac muscle has …

1) Adhering/ anchoring junctions - actin filaments attach thin filaments in the muscle sacromeres to the cell membrane
2) desmosomes - sites of strong adhesion - help keep muscle cells connected when they contract
3) facilitate electrical communication - provide direct contact between cardiac cells - facilitate electrical communication - waves of depolarisation spread rapidly over heart - passing cell to cell

Question 8

Describe tissue specific cell & matrix organisation – architecture of muscle

Answer 8

Muscle tissue
Epimysium fibrous muscle tissue surrounding each muscle The epimysium protects against friction

Perimysium is a sheath of connective tissue surrounding each bundle of muscle fibres, it contains collagen and intramuscular fat, blood vessels and nerves

The perimysium transmits lateral contractile movements The endomysium surrounds each muscle fibre and can associate with capillaries and nerves

The connective tissues present in the muscle are used for supporting the muscle fibres and insulating the muscle fibres

Question 9

Describe tissue specific cell & matrix organisation - nerve

Answer 9

Endoneurium –surrounds individual nerve fibres
Perineurium –Within the nerve, axons targeting the same anatomical location are bundled together into groups known as fascicles –perineurium encloses this fasicle
Epineurium –is dense irregular connective tissue and encloses the entire nerve, as well as the blood vessels

All connective tissue present in the nerves effectively works as insulation and shock absorbance to ensure that damage to the axons does not occur

Question 10

Extracellular matrix – principles of function of cells, fibres (collagen & elastic) and ground substance (GAGs and proteoglycans); relation of cells to ECM

Answer 10

Is a complex combination of secreted proteins that are involved in holding cells + tissue together

The ECM contains GAGs and fibrous proteins such as elastin, collagen, fibronectin, and laminin

Question 11

describe the cells enviroment

Answer 11

cells sit in a matrix of other molecules and other cells.

this means that cell behaviour is influenced by the molecules surrounding the tissue.