Tissues

Question 1

what is 5 functions of bone in vertebrates

Answer 1

”- Support: maintains upright posture
- Protection: protects the brain and internal organs
- Movement
- produces red blood cells
- stores minerals and fats”

Question 2

what are the 3 types of cartilage and where are they found

Answer 2

”- Hyaline: surfaces of joints
- Fibrous: menisci of synovial joints
- Elastic cartilage: - ear flaps and larynx”

Question 3

whats the function of cartilage

Answer 3

”- Structure and support to other tissues
- Cushions joints and smooths movement of joints
- ESSENTIAL for development of long bone”

Question 4

whats the outer layer of cartilage called

Answer 4

perichondrium

Question 5

what are the 2 layers of cartilage

Answer 5

”- Fibrous layer

Chondrogenic layer

Question 6

What are the features of fibrous layer of cartilage

Answer 6

contains fibroblasts that produce collagenous fibres

Also contain blood vessels which supply the cartilage with nutrients and oxygen

Question 7

What are the features of chondrogenic layer of cartilage?

Answer 7

– Remains undifferentiated and can form chondroblast”

Question 8

what is ossification

Answer 8

the process of forming bone

Question 8

why are chondroblasts important?

Answer 8

“Chondroblasts secrete a substance called Extracellular matrix
Chondroblasts mature into chondrocytes”

Question 9

what is direct ossification

Answer 9

”- intramembrane
-Mesenchymal cells → bone

e.g. Flat bones of skull

(primary bone formation in first 2 months)”

Question 10

what is indirect ossification

Answer 10

“-Endochondral
- Mesenchymal cells → Cartilage → Bone

• bone formation after 2 months
• Most of the bones of the skeleton are formed in this manner”

Question 11

what is the chemical composition of bone

Answer 11

“organic = 1/3 of mass
- OSTEO cells
- matrix- collagen - strength to bone prevents it from brittleness

inorganic = 2/3 of mass
- inorganic mineral salts:
calcium phosphate
calcium hydroxide
calcium carbonate
- provides hardness
- bone is extremely strong but not brittle”

Question 12

how are bones classified by shape

Answer 12

”- long
- short
- flat
- irregular”

Question 13

what is the gross anatomy of a long bone

Answer 13

”- diaphysis - shaft
- epiphysis - end
- medullary cavity - canal
- periosteum - covering
- endosteum - canal lining
- articular cartilage - on endsof bones for smooth movement
- marrow
yellow - fat storage
red - blood cell formation”

Question 14

what are 4 bone cells and their functions

Answer 14

“Osteoclast- resorbs bone (made from macrophage)

Osteogenic/ osteoprogenitor cell- stem cell

Osteoblast- forms bone matrix

Osteocyte- maintain bone tissue”

Question 15

describe osteoblasts

Answer 15

Secrete OSTEOID: collagen and non-collagen proteins + calcium binding protein osteocalcin. the osteoblasts become TRAPPED in the matrix. Mature into osteocytes.

Question 16

describe osteocytes

Answer 16

Mature bone cells Are unable to undergo cell division Are networked to each other via long cytoplasmic extensions that occupy tiny channels called canaliculi used for exchange of nutrients and waste

Question 17

describe osteoclasts

Answer 17

“Different cell line from the other cells. Actually from monocytes (white blood cells). Multinuclear giant cells – fusion of many cells. Ruffled border – facing towards bone (SA – resorption).

• They secrete acid and enzymes (acid phosphatase) to breakdown bone tissue
• Dissolve bone
• Release calcium and phosphate yo replace old with new
• To change the shape of bone in response to stress
• Hormones

PTH – increase activity (increase plas. Ca2+)

Calcitonin – decrease activity”

Question 18

why is bone remodelling important

Answer 18

“1. Homeostasis – maintaining plasma Ca2+ levels in your plasma
2. Removing old damaged tissue and replacing it with new. E.g, breaking a bone, the formation of a bone callus and then shaving away that callus”

Question 19

sytructure of compact bone

Answer 19

“Compact:
made up of osteons
- cement layer
- lamalle
-haverisan canal
-canalicculi
lacuna

Question 20

structure of spongy bone

Answer 20

Spongy:
- honeycomb structure
- -Spaces often filled with red bone marrow
- No Haversian system
- no central canals, no perforating canals
- There are blood vessels but they are found in the spaces between the trabecullae
- Nutrients are able to diffuse through the tissue via extracellular fluid”

Question 21

what are 5 functions of blood

Answer 21

”- Transport: including nutrients, gases, wastes
- Temperature Regulation: by altering blood flow through the skin
- Immunity: protection against pathogens
- Communication: hormones
- Defence: clotting following a wound”

Question 22

what is the composition of blood

Answer 22

”- plasma (55%)
- red blood cells- eryth
- white blood cells- leuco
- platelets - thrombo”

Question 23

what is haematpoiesis

Answer 23

the process of blood cell production

Question 24

where is blood formed in the fetus vs in adults

Answer 24

"in the fetus: liver and spleen and from bone marrow in adults: **rbc/granular leucocytes/platelets** produced in red bone marrow, **leucocytes** produced in myeloid tissue (red bone marrow) & some mature in lymph tissue"

Question 25

RBC: Structure

Answer 25

- biconcave disc that is round and flat without a nucleus, mitochondria and endoplasmic reticulum - contain haemoglobin which combines with oxygen at high partial pressures of oxygen - can change shape without breaking - Diameter 7μm

Question 26

RBC; Function

Answer 26

- Carry oxygen in the form of oxyhaemoglobin. Each Hb molecule carries eight atoms of oxygen - Hb readily combines with oxygen when oxygen is at a high concentration eg. lungs - Hb releases oxygen where it is at a low concentration eg respiring tissue- muscles - also carries carbon dioxide some non-mammalian animals may have nuclei, eg, fish

Question 27

WBC function

Answer 27

- combat microbes either by phagocytosis or antibody production

Question 28

name the 5 types of white blood cells (graular and nongranular) and describe their function and shape

Answer 28

"**Granular** - neutrophils (multilobed nucleus)- phagocytosis - Basophils: secrete heparin and histamine (least common) involved in allergic response - Eosinophils: Combat parasitic infection/allergic response (pink/red granules) **Non Granular** - Monocytes: phagocytosis- When leave the bloodstream and transform within tissues = macrophages (one-legged horse) - Lymphocytes: T cell – adaptive immune response (cell-mediated immunity) B cell –humoral immunity (relating to antibodies)

Question 29

platelets: structure and function

Answer 29

"- In mammals they have no nucleus - involved in haemostasis – by forming a platelet plug where fibrin allows platelets to aggregate together."

Question 30

Plasma Structure and function

Answer 30

"- straw-coloured liquid  that carries the cells and the platelets which help blood clot - also contains, carbon dioxide, glucose, amino acids, proteins and water (90%) etc" - contains the proteins Albumin (maintains osmotic pressure), Globulin(Importants for immune response- antibody production), Fibrinogen (essential for blood clotting)

Question 31

define homeostasis

Answer 31

"-Maintaining a stable environment within the body. Conditions that need to be controlled within limits include: - pH - Blood glucose levels - Temperature control - Water content - Ion content"

Question 32

what is the role of blood inn homeostasis

Answer 32

"role of blood in homeostasis - Blood glucose levels are hormone controlled, (insulin & glucagon). - Temperature control: vasodilation and vasoconstriction - Water content: hormone control (ADH) - Ion content: blood is filtered by the kidneys - Maintaining blood pH (buffer system)"

Question 33

what are 3 types of muscle

Answer 33

"- **skeletal** - **smooth** - **cardiac**"

Question 34

function of muscles

Answer 34

"- movement- skeletal muscle contraction - posture- continual adjustment of skeletal muscles - protection- skeletal muscles in abdominal wall - sphincter control- skeletal muscle control opening and closing of sphincters eg swallowing - movement along gi tract- smooth muscle generates peristalsis - Temperature regulation- shivering, skeletal muscle"

Question 35

describe the function of skeletal muscle

Answer 35

"- **voluntary control** - **striated appearance** - **not electrically connected, each needs to receive a nerve impulse to contract unlike cardiac and smooth** - attached to bone by tendons"

Question 36

structure of skeletal muscle

Answer 36

"- muscle fibres (myocytes) are classified as cell- multi nuclei, large, long, many mitochondria - myofibrils are organelles each contaisn many myofilaments (actin myyosin) - sarcolemma = plasma membrane contains t tubules - sarcoplasmic reticulum- endoplasmic reticulum - T tubules store calcium ions - Repeating units of overlapping actin and myosin filaments are organised into sarcomeres"

Question 37

describe the neuromuscular junction

Answer 37

"- specialized form of **synapse** that forms between a neurone and myofibril. - some motor nuerones only affect one cell while others branch to NMJs causing a cluster of muscles fibres to contract - action potrntial travels down motor nuerone to muscle which triggers Ach to diffuse across the synapse and causes contraction"

Question 38

steps of muscle contacion

Answer 38

"1. Calcium ions bind to troponin on actin filament, changes its hape which pushes away tropomyosin, exposing myosin binding sites. 2. Myosin binds to the exposed Myosin binding sites on the actin forming a ‘cross-bridge’. 3. the myosin heads tilts backwards, pulling the actin filament past the myosin filament ‘the power stroke’. (ADP and Pi are released) 4. A new ATP molecule attaches and breaks the cross bridge 5. The myosin head swings back forwards and is ready to bind to another binding site further along the actin"

Question 39

describe the structure of smooth muscle

Answer 39

"- Smaller than skeletal or cardiac myocytes - Not striated – myofilaments not arranged in sarcomeres - Less regular – spindle shaped - Mononuclear - No T-tubbules - Not attached to bone"

Question 40

where can smooth muscle be found

Answer 40

"-Involved in internal transport - walls of uterus - walls of digestive tracts - blood vessel walls"

Question 41

how does smooth muscle function

Answer 41

"- Involuntary contraction - Stimulated by the autonomic nervous system, hormones and in response to stretch - Slower than skeletal muscle but able to hold for longer - Less cross-bridges are formed, but for a longer duration* - Maximum contractile force is the same - ATP generation is mainly via oxidative phosphorylation"

Question 42

describe cardiac muscle

Answer 42

"- Involuntary muscle contraction - Striated muscle - ATP generated by oxidative phosphorylation - Branched - Intercalated disks"

Question 43

what are sarcomeres

Answer 43

Repeating units of overlapping actin and myosin filaments are organised into sarcomeres

Question 44

what are the 2 types of muscle fibre and describe them

Answer 44

- Fast twitch - slow twitch

Question 45

describe fast twitch muscle fibres

Answer 45

**Fast twitch** - Short term - Fast contraction velocity - Large diameter - Increased CP - More anaerobic production of ATP

Question 46

describe slow twitch muscle fibres

Answer 46

**slow twitch** - Endurance - More blood capillaries - Increased myoglobin - More aerobic ATP production