PHYSIOLOGY Flashcards
(111 cards)
1
Q
what are the three types of muscle
A
skeletal
cardiac
smooth
2
Q
what is the function of each type
A
skeletal-attached to the bone, supports and moves the skeleton
cardiac-muscle of the heart, propels blood through the circulatory system
smooth-surrounds hollow organs of the body, controls the movement of contents through the organ
3
Q
breakdown of the muscle structure
A
muscle ( epimysium )
fascicle (perimysium)
muscle fibre (plasma membrane -sarcolemma )
myofibril (sacromere)
myofilament (actin and myosin )
4
Q
what are the two types of fibres
A
long fibre- large movements, high velocity eg hamstrings
short fibre- short movement, high force eg quadriceps
5
Q
what is a motor unit
A
a single motor neurone and the muscle fibre it innervates
6
Q
which chemical is used in contraction
A
ATP
7
Q
what are three systems of generating ATP
A
ATP phosphocreatine (PCr) oxidative system (aerobic) glycolytic system (anaerobic )
8
Q
explain the need for ATP PCr system
A
ATP direct energy needs 2 seconds to exhaustion
PCr restores ATP level to 3-15 seconds to exhaustion ( as in it will be finished in about 15s)
9
Q
explain the need for the glycolytic and oxidative system
A
they use aerobic and anaerobic methods to generate more ATP
10
Q
what are the three types of muscle fibres
A
type I - slow twitch/oxidative
type IIa - fast twitch/oxidative
type IIb - fast twitch/glycolytic
11
Q
are all muscle fibres of one motor unit the same type
A
yes
12
Q
how to differentiate between the muscle fibre types
A
type I- dark
type IIa - lighter
type IIb - translucent
13
Q
how to differentiate between muscle fibre types
A
type II stains metachromatic and type I stains dark blue
14
Q
what is the function of a satellite cell
A
it is attached to the mature muscle fibre and it repairs it if its damaged
15
Q
what are the functions of two regulatory proteins
A
tropomyosin-bocks myosin binding site
troponin-binds calcium
16
Q
explain excitation contraction coupling
A
action potential in nerve-release of neurotransmitter at N/M junction-action potential in muscle-AP transferre to T tubule- SR releases calcium-muscle contracts
17
Q
what holds the myosin and actin filaments together
A
titin filament
18
Q
what is the function of nebulin
A
provides rigidity and ensures the actin filaments stay in place
19
Q
what are the layers of cardiac muscle called
A
myocardium
20
Q
what is the function of the sympatheitic system
A
releases noradrenaline
increases heart rate and force of contraction
21
Q
what is the function of parasympathetic system
A
vagus nerve
releases acetylcholine
dominant effect at rest
depresses heart rate and force #
22
Q
whats th structure of a cardiac muscle
A
- striated muscle
- uninucleate
- cells act as a syncytium - connected in series with intercalated discs, which are gap juctions and desosomes
23
Q
how does excitation-contraction coupling work
A
initial depolarisation in sinoatrial node- action potentialin muscle-AP transmitted to T tubule-calcium influx from extracellular space-SR releases calcium CICR(calcium induced calcium release)- muscle contracts
24
Q
how to ensure that the cardiac muscles relax
A
an extended refractory period by the calcium VGC slowly opening which keeps the membrane depolarised for longer
25
what is the structure of smooth muscle cells
long spindle shaped cells
uninucleate
no neuromuscular junctions-it has nerve branches with small swellings called varicositites
it has no sarcomere
26
what are the functions of myosin filaments
site of ATPase activity but very slow rate
low energy consumption so very fatigue resistant
allows muscle tone eg bladder
27
what are the functions of actin filaments
consists of actin molecules but longer
| no troponin- function replaced by calmodulin in cytoplasm
28
what are the functions of calmodulin
involved in calcium binding
| activates contraction
29
where does the actin bind insmooth muscle
to dense bodies
30
what is another word for transverse tubules in the smooth muscle
caveolae
31
what does smooth muscle respond to
```
neurotransmitters
hormones
local chemical changes eg pH
stretch
spontaneous electrical activity
```
32
what are the two types of smooth muscle
multiunit- discreet cells, richly innervated by nerves, contract indpendently of neighbour
single unit/visceral - cells linked by gap junctions, respond to a variety of signals, many cells respond as a single unit, spontaneously active
33
what is the excitation contraction coupling
stimulus-muscle membrane depolarises-calcium influx from extracellular space CICR-calcium binds to calmodulin- ATPase activated- muscle contracts
34
what are the different charcaterisitics of smooth muscle
```
very versatile
very fatigue resistant
low energy consumption
allows muscle tone
contract over much greater lengths
```
35
what are the main functions of the skeletal system
```
support-provides rigid structure
protection of internal organs
reservoir for calcium,, inorganic phosphate and other minerals
storage of lipids (yellow marrow)
blood cell production (red marrow)
```
36
what is the end of bone/growth plate called
epiphysis
37
what is the bone shaft called
diaphysis
38
what is the yellow marrow called
medullary (triglyceride store)
39
what is the red marrow called
spongy/cancellous bone (blood cell production)
40
what is the membrane with osteoblasts and osteoclasts on inner layer called
periosteum/ endosteum
41
what is the lamellae
rings of hard calcified bone matrix
42
what is lacunae
spaces which hold osteocytes
43
what is osteon
circular column of concentric lamellae
44
what is Haversian canal
central space containing blood vessels and nerves
45
what is canaliculi
small channel with osteocyte processes
46
what are osteoprogenitor cells
- mesenchymal bone stem cells
- produce osteoblasts
- proliferative, involved in growth and repair
47
what do osteoblasts do
secrete collagen to create a matrix (scaffold) which will become calcifies (osteogenesis )
-mature into osteocytes when surrounded by calcified matrix
48
what are osteocytes
- do not divide
- help maintain protein and mineral content of the matrix
- help repair damaged bone
49
what are osteoclasts
- giant multi nucleated cells
- secrete acids and proteases to dissolve bone (osteolysis)
- come from the same lineage as white blood cells
50
where are osteoclasts, osteoblasts and osteoprogenitor cells found
osteoblasts- lacunae
osteoclasts -line medullary cavity
osteoprogenitor-on the inside of the periosteum
51
what is bone composed of (organic matrix)
- collagen matrix(osteoid), gives elasticity and resistance-95%
- ground substance, extracellular fluid and proteoglycans chondroitin sulfate and hyaluronic acid
- mineral deposited on matrix (calcification), contributes strength and resistance
52
what is the formula for hydroxyapatite
calcium phosphate+calcium hydroxide
Ca3(PO4)2+Ca(OH)2 -->Ca10(PO4)6(OH)2
53
what stops the hydroxyapatite from forming
inhibitors such as pyrophosphate
54
what regulates pyrophosphateand how
alkaline phosphatase
- breaks down pyrophosphates
- collagen fibres then develop hydroxyapatite crystals for calcification
55
where does alkaline phosphatase come from
released by osteoblasts
56
what happens as a result o deficiency in alkaline phosphatase
soft bones
57
how does calcium level disruption lead neuromuscular excitability (twitching)
binding to plasma proteins acting as ion channels
low levels- hypocalcaemic tetany (muscle spasms)
high levels- hypercalcaemia and cardiac arrhythmia (rapid changes)
58
what is bone resorption
breakdown of bone which results in the release of calcium into the bloodstream
59
which hormones are responsible for increasing and inhibiting bone resorption
Parathyroid hormone (PTH) increases and Calcitonin inhibits controlled by negative feedback
60
where is parathyroid hormone released from
by parathyroid gland
61
where is calcitonin released from
by prarfollicular cells in the thyroid gland
62
give an example of the negative feedback cycle in calcium homeostasis
calcitonin released- osteoclast activity decreases- ca+ in the bone increases- plasma ca+ decreases- calcitonin release decreases-plasma ca+ increases
63
where is bone marrow found in infants and adults
infants-medullary cavity and all areas of spongy bone
adults-in the diploe of flat bones and the head of the femur and humerus
64
what happens to the amount of yellow marrow in the bone as we age
increases starting at the centre of the bone
65
function of red marrow
supplies nutrients to the osteocytes
| forms red and white blood cells
66
function of yellow bone marrow
stores fat
| may convert back to red marrow if there is severe bleeding
67
what is ossification/osteogenesis
process of bone formation
68
when do bones form
- during development
- during childhood growth
- to remodel bone e.g. response to stress
- repair
69
what does the bone replace
cartilage and chondrocytes deposition create a model which is replaced
70
what are dietary requirements for bone growth
- minerals such as calcium, phosphorus, magnesium, fluoride
- vitamins D(collagen), A(osteoblast activity and K
- protein
71
what factors affect growth
- sex-males taller than females
- sex hormones- end of puberty ceases growth
- stress- cortisol inhibits growth and increases breakdown
- nutrition
72
how does structure of the bone change as we age
deposition of bone by osteoblasts from the outside ( periosteal layer)
resorption of bone by osteoclasts on the inside ( endosteal layer)
73
what does physical stress and illness do to bone structure
physical stress increases deposition and illness decreases deposition
74
how do osteocytes regulate bone remodeling and repair
- support osteoclastogenesis
- secrete growth factors to support bone formation
- secrete sclerostin to inhibit bone formation
75
what happen during the breakdown of bone
osteoclasts form grooves called resorption bays as they break down bone matrix
hydrogen ions and hydrolytic enzymes are released to dissolve the bone ( osteolysis)
the products of bone breakdown end up in the blood plasma thus increasing plasma calcium levels
76
what affects bone density
exercise can increase bone density
77
what are the different types of fractures
open-skin is broken
greenstick-more common in children
comminuted-fracture splintering/ crushing
impacted-fracture pushes bone into interior
78
what are the phases of bone healing
reactive, reparative, callus formation, bone remodeling
79
what happens in the reactive phase of bone healing
- blood vessels crossing the line of the fracture are broken
- a blood clot (fracture hematoma) rapidly forms around the fracture site
- surrounding bone cells die due o lack of vascularisation
- cell death and inflammation
- clean up operation-immune system
80
what happens in the reparative phase of bone healing
- vasculogenesis of the hematoma-removal of dead cells by phagocytes
- fibroblasts move into the fracture site and start to build new collagen fibre
- cells from the periosteum develop into chondroblasts and produce fibrocatilaginous callus
- the ends of the bone are being to stabilize usually takes 3 weeks
81
what happens during callus formation
- osteoprogenitor cells from the periosteum develop into osteoblasts and produce spongy bone trabeculae
- trabaculae join up living and dead bone fragments
- fibrocartilage is converted to spongy bone, the callus is now a bony callus
- the bony callus lasts 3-4 months
82
what happens during bone remodeling
- osteoclasts resorb dead bone
- spongy bone is replaced by compact bone
- a thickened area may remain on the surface of the bone
83
what is the approximate blood pressure in the pulmonary circuit
28/8 mmHg
84
what is the approximate blood pressure in the systemic circuit
120/80 mmHg
85
what is heart failure
the pathological state in which the heart is unable to pump blood at a rate required by metabolizing tissues or can do so only with an elevated filling pressure
86
what is the relaxation of the atria and ventricles called
diastole
87
what is the contraction of the atria and ventricles called
systole
88
which node initiates the electrical signal
the SA node ( sinoatrial)
89
what is atriole systole and what wave is it
when the atria contract and blood fills the ventricles and this is the P wave
90
what is the first part ventricular systole and what part of the wave is it
when the ventricles contract and the AV valves close called the QRS complex
91
what is the second part of systole and what part of the wave is it
semilunar valves open and blood is ejected this is the T wave
92
what is the first part of ventricular diastole
the semilunar valves close and blood flows into the atria
93
what is the second part of ventricular diastole
chambers relax and the blood refills the ventricles passively
94
what is the function of desmosomes
hold the muscle cells together tightly
95
what is the function of the intercalated disks
link muscle cells together and contain the desmosomes and gap junctions
96
what is the function of gap junctions
allow passage of action potentials from one cell to the next very quickly
97
what is a feature of myocardial cells
can simultaneously depolarize and this means an electric current can be automatically produced so the SAN cells dont need neighbor cells to depolarize first
98
what is the importance of fibrous tissue between the atria and ventricles
it lacks gap junctions and electrically isolates atria from ventricles and so provides a border
99
what is the transmembrane potential, TMP
the electrical potential difference between the inside and outside of a cell
100
what is the difference between chemical and electrical potential
chemical is ions moving down its concentration gradient and electrical is ions moving away from ions/molecules of like charge
101
what are cardiomyoctes
the cells responsible for generating contractile force in the intact heart.
102
what are the properties of cardiac ion channels
selectivity- only permeable to a single type of ion based on their physical configuration
voltage-sensitive gating- dependent on a specific TMP range
time dependance- some are configured to close either slower or faster than others
103
what is the pacemaker potential
when the cells of the SAN depolarize over time with the movement of ions causing the resting membrane potential to decrease
104
what happens once the membrane potential exceeds the threshold and after how many seconds does this happen appproximately
an action potential is generated and this happens automatically every 0.8s
105
why does AVN depolarize more slowly than the SAN and how slowly approximately
because this allows for a very short delay so that the blood can fill the ventricles before they contract usually about 0.09s
106
what is excitation contraction coupling
the process by which an electrical action potential leads to contraction of cardiac muscle cells.
107
how is excitation contraction coupling achieved
converting a chemical signal into mechanical energy via contractile proteins
108
what mediator is important in convert the electrical excitation into physical contraction
calcium by cycling in and out of the monocytes cystol during an action potential
109
what causes the pacemaker potential/ plateu in cardiac potential
funny channels in the SAN open and sodium ions enters which causes depolarization which opens gated calcium channels and they enter the membrane slowly and so it gradually depolarizes another type of voltage gated channel opens and calcium enters the cell rapidly and this leads to rapid depolarization which is the cardiac action potential
110
what is an example of transient channel and at what potential does it open
T type Ca++ open briefly at -50mV
111
what is an example of a long lasting channel and at what potential does it open
ca++ open at -40mv full depolarization
