W14 Physiology of Ageing Flashcards
1
Q
What is ageing?
A
- Decrease in functional capacity
-molecular to organ level
-genetic factors
-environmental factors - Ageing & wear & tear (leads to) = disease/disablement
-Variety of theories
2
Q
What are the changes in muscle physiology with age? (6)
A
- Loss of lean body mass
- Infiltration of fat and connective tissue
- Altered muscle metabolism
- Insulin resistance
- Reduced levels of key regulatory hormones
- Impaired oxidative defence
3
Q
What is sarcopenia?
A
- Sarcopenia = loss of muscle mass (and strength) due to ageing
-slow twitch fiberes (t1)- endurance activities eg walking long distances
-fast-twitch fibres (t2)- short ‘explosive’ activities scuh as sprinting
Sarcopenia: assoc with changes of fast twitch fibres, slow twitch relatively unaffected - By age of 80 40% may be lost
-Reduced cross-sectional area and functionality
-Loss of motor neuron fibres and degeneration of NMJ - Disuse atrophy (ageing is associated with becoming more sedentary) may contribute to changes
4
Q
Cardiovascular changes
A
- Gradual thickening of the tunica intima and tunica media of large and medium-sized arteries
- Calcification
-gradual loss of elasticity and stiffening of the arteries - often reflected by increased blood pressure - Atherosclerosis
- Reduced elasticity and increased resistance to blood flow of aged and occluded arteries
-heart’s ventricles have to pump with greater force
-Hypertrophied - Changes in the heart’s conductive system
- Filling of the ventricles also slows with age
-decrease in the maximal heart rate achievable during exercise
5
Q
Cardiovascular changes: Cardiac output (CO) = HR × SV (stroke Volume)
A
- Dec Max CO with age
- Primarily due to DEC HRmax (= approx. 220 – age)
-β-adrenergic stimulation (dec β1 receptors)
-Altered conductivity - Max SV mainly due to increased peripheral resistance (possible also dec left ventricular contractility)
6
Q
Pulmonary changes
A
- Increase in rib calcification
- Age-related reduction in respiratory muscle strength
- loss of muscle mass in the diaphragm and intercostals
-Particularly in inactivity
frequency with which cilia beat decreases with age
-Infections - Sensory receptors less sensitive
-the coughing reflex may not be triggered - cartilaginous rings that hold the upper airways open gradually calcify with age
-increases the diameter of the larger airways, particularly the trachea and bronchi, causing this dead space to grow
7
Q
Overall Pulmonary changes:
A
- Loss of elasticity of lung tissue and chest wall
↓ Vital capacity and forced expiratory volume in 1 sec
↑ Residual volume
↓ Maximal minute ventilation
reduced delivery of oxygen to the blood and a decrease in oxygen saturation
8
Q
What is Immunosenescence?
A
- deterioration of immune function seen in elderly
- increased susceptibility to;
-infection
-cancer
-autoimmune diseases
Almost all components of the immune system are adversely affected by ageing
-adaptive immune system particularly affected
9
Q
Age: Innate immune response
What occurs?
A
- Skin: thinner, drier (fewer secretions) and less elastic
- Neutrophils: reduced phagocytosis (build- up of debris) and respond less to chemotaxis
- Macrophages: phagocytic capacity reduced
- Natural killer cells: Although numbers increase cytotoxic abilities decrease
10
Q
Age: Adaptive immune response
What occurs?
A
- T cells mature into immunocompetent lymphocytes in the thymus gland
-Shrinks with age
-Fewer matured T cells (v few naïve T cells)
-More autoantibodies
-Decline in T cell receptors - Bone marrow produces fewer mature B cells
-Humoral response: shorter duration and decreased specificity
-Antibody responses to infectious agents and vaccines tend to decrease in older people
11
Q
Summary
A
- Sarcopenia – loss of muscle mass
- CO reduced
- Changes in Respiratory system
-loss of elasticity and calcification
-changes in functional capacities and functions - Immune system
-Changes in innate but larger changes in adaptive
-Atrophy of thymus
