Aging & Muscle Flashcards
1 - Describe the types of muscle cells 2 - Define and describe sarcopenia 3 - Describe the causes and consequences of ageing
What are the 3 types of muscle cells?
- Skeletal
- Cardiac
- Smooth
What are the characteristics of skeletal muscle?
Striated Attached to the bone Cylindrical fibres that are parallel Banded appearance under a microscope Nuclei in periphery Voluntary muscle (conscious control)
What are the characteristics of cardiac muscle?
Striated One nucleus Branched Cardiocytes/cardio monocytes Involuntary
What are the characteristics of smooth muscle?
Non-striated Involuntary Small cells One nucleus Spindle-shaped Surrounds tissue & walls of hollow organs
What is sarcopenia?
A syndrome characterised by progressive and generalised loss of skeletal muscle mass and strength with a risk of adverse outcomes such as physical disability, poor quality of life and death
Symptoms of sarcopenia
Weakness
Poor balance
Loss of muscle mass
Loss of endurance
What is recommended to maintain healthy muscle with ageing?
Increased protein intake to compensate for anabolic resistance and hypermetabolic disease
1 - 1.5g protein / kg BW / day
Exercise & resistance training
3 cellular mechanisms of ageing
Telomere length
Oxidative stress
Mitochondrial dysfunction
List the 3 types of muscle cells and give 2 characteristics for each type
Skeletal - Striated / Banded appearance / Connected to the bone / Voluntary / Cylindrical fibres that are parellel / Nuclei in periphery
Smooth - Non-striated / Surrounds tissue and walls of hollow organs / Involuntary / Small cells / One Nucleus / Spindel shaped
Cardiac - Involuntary / Branched / One nucleus / Cardiocytes / Striated
Compare and contrast smooth muscle cells with cardiac muscle cells (10 marks)
Similarities
- involuntary
- One nucleus
- Innervated by autonomic nerves
- Do not fatigue
Differences
- Cardiac striated, Smooth non-striated
- Cardiac only found in the heart, Smooth lines the walls of internal organs
- Cardiac responsible for pumping blood, Smooth moves internal organs to facilitate the function
- Cardiac branched chains of cells with intercalated discs, Smooth single tapering cells
- Cardiac has an intermediate speed of contraction, Smooth has a low speed of contraction
Name 3 body systems and 1 effect smooth muscle cells have within each of these
Integumentary system
- Regulates blood flow to superficial dermis and elevates hair on skin
Cardiovascular system
- Regulates blood pressure and distribution of blood
Urinary system
- Changes filtration rate in kidneys and transports urine into and out of the bladder
Respiratory system
- Changes the diameter of respiratory pathways and changes resistance to airflow
Digestive system
- Moves food along digestive tract and ejects bile from the gallbladder
Outline 5 physiological changes associated with ageing
Blood vessels loose elasticity
Cardiac hypertrophy (abnormal enlargement/thickening of heart muscle)
Thickening of valves
Calcification of blood vessels
Reduced strength of respiratory muscles
Pressure in pulmonary artery increases
Intestinal villi shrink, reducing surface area
Loss of neurons
Reduced immune function
Total muscle mass declines
3 factors that contribute to sarcopenia
Inadequate nutrition / malabsorption
Age-related - Sex hormones, apoptosis, mitochondrial dysfunction
Disuse - Physical inactivity, immobility
Neurodegenerative disease - motor neuron loss
Cachexia - weakness and wasting of the body due to chronic illness
Describe the oxidative stress theory of ageing
Oxidative stress occurs when the production of free radicals exceeds the ability of antioxidants to defend against the free radicals
What happens in oxidative stress?
Strands break in DNA
Oxidation of polyunsaturated fatty acids in lipids
Oxidation of amino acids in proteins
