Updated Muscles Lecture PDF

BIOL 116: Human Biology Muscles – structre, function and public health Pūkenga: Dr Kaaren Mathias Appreciation for much of content – Dr Sibi Walter Adapted for presentation: Arindam Basu  Musculoskeletal (MS) system and health Learning objectives Students can...

BIOL 116: Human Biology Muscles – structre, function and public health Pūkenga: Dr Kaaren Mathias Appreciation for much of content – Dr Sibi Walter Adapted for presentation: Arindam Basu  Musculoskeletal (MS) system and health Learning objectives Students can describe Key components of the MS system Functions of the MS system Factors contributing to decline of the MS system health Healthy maintenance of the MS system  Components of the MS system How many bones (kōiwi) are there? How many muscles (weu uaua) are there? Ligaments short band of tough, flexible fibrous connective tissue which connects two bones or cartilages or holds together a joint. Tendons a flexible but inelastic cord of strong fibrous collagen tissue attaching a muscle to a bone. Cartilage firm, flexible connective tissue found in various forms in the larynx and respiratory tract, in structures such as the external ear, and in the articulating surfaces of joints. It is more widespread in the infant skeleton, being replaced by bone during growth. Muscle a band or bundle of fibrous tissue in a human or animal body that has the ability to contract, producing movement in or maintaining the position of parts of the body. "the calf muscle" Put it all together  Components of the MS system Bones AXIAL APPENDICULAR Muscles Tendons Ligaments Cartilages Bursae  Components of the MS system Muscles Tendons Ligaments Cartilages Bursae  What are the functions of the muscles in the musculo-skeletal system? Maintain posture and body position Make us move Protect vital organs Help with venous return (blood back to heart) Convert chemical energy to mechanical energy  What influences strength of muscles?  Muscle strength is determined by many factors, including:  Size and type of muscle fibers, and the nerves that activate them  Stretch of the muscle  Speed of muscle contraction  Age  Gender  Limb and muscle length  Genetics  Hormones (testosterone and androgens)  Type of exercise performed  Diet Pair and share What factors do you think influence the strengths of muscles? What influences strength of muscles? Size and type of muscle fibers, and the nerves that activate them Stretch of the muscle Speed of muscle contraction Age Gender Limb and muscle length Genetics Hormones (testosterone and androgens) Type of exercise performed Diet  Factors affecting the MS system Muscle hypertrophy and atrophy Autopsied vastus lateralis (VL) of ∼30 and ∼72 year old men Muscle size of the VL was 18% smaller in the older men A 39% reduction in the number of fibres ∼20% greater amount of non-contractile material in the old muscle,  Sarcopenia - the loss of muscle mass and muscle function, is a major health condition associated with ageing Sarcopenia (Greek ‘sarx’ or flesh + ‘penia’ or loss) Measures – hand grip strength, knee extension strength and peak expiratory flow Higher risk – low body mass index, nursing home residence, Asian people, men, other health problems  Factors affecting the MS system Decline in the metabolic rate due to sarcopenia 3-8% decline in muscle mass from 30 years Decline of basal metabolic rate from 20 years There is typically poorer usage of glucose and amino acids What are some of the public health impacts of older people having loss of muscle strength? Increased risk of Falls (4 times higher) Hospitalisation Disability Loss of mobility Fractures Higher risk of early death  What strengthens muscles (hypertrophy vs atrophy)? Muscle homeostasis is a balance between muscle protein synthesis and muscle protein breakdown Balance protein food intake and physical activity Dietary protein is required to build muscle protein Lack of use of a muscle leads to atrophy and protein breakdown For muscle atrophy to occur, MPB must exceed MPS What prevents sarcopenia? combining lifestyle, nutritional, pharmacological and physical interventions is the most promising strategy What do you think should be in guidelines?  The importance of exercise – especially resistance Mechanical stress stimulates the deposition of mineral salts and collagen fibres. Bigger muscles– regular exercise Reduce NMJ degeneration and disuse atrophy Reduce fat accumulation Physically active people -effect of mitochondria releasing energy is maintained till age 75  Aerobics results in little gain in strength nor in increased bone mineral density  Heavy resistance training, repetition maximum targets to bone and muscle specific sites- such as femoral neck for fracture reduction NB Quadriceps strength is important for maintaining knee stability, gait, and balance USE IT OR LOSE IT Healthy MS system maintenance  Summary You can describe:  The structure of the key components of the MS system  Functions of the MS system  Define sarcopenia.  The factors contributing sarcopenia  The public health measures to maintain muscle strength and function  Any questions? Pātai? [email protected]