Transcript General body responses to noxas

General body responses to noxas
Prof. Tatár
Dept. of Pathophysiology
•
Injurious influences of noxas do not only
produce local cell´s injury, but also elicit
general body responses
• Physiological reactivity – pathological reactivity
• Responses to stressors:
1. Mobilisation of defensive and regulatory
mechanisms and reserves to overcome
harmful effects of noxas
2. To maintain morphological and functional
integrity of the organism, but there is
temporary disturbed homeostasis - allostasis
•
Integration of various components of living
organisms becomes essential to their survival
• Integration is effected by:
1. Central nervous system – coordinates,
interprets, and control the interaction
between the individual and the environment
2. Endocrine system – mobilization of metabolic
reserves
3. Integrated cooperation of CNS and ES helps
minimise the response of the organism to
stressful stimuli
• W.B. Cannon – 1914 : applied the engineering
concept of stress in a physiologic context
• H. Selye – 1946 :
Stress = the physiologic changes that follow
the application of a stressor to an living
organism; non-specific physiologic response
Stages of stress
• Alarm stage
sympathetic n. s. and pituitary gland are aroused
and the body´s defences are mobilised
• Stage of resistance
hyperactivity of the axis hypothalamus-pituitary
gland-suprarenal cortex
• Stage of exhaustion
continuous stress causes the progressive
breakdown of compensatory mechanisms and
homeostasis – allostatic overload
impairment of body systems can lead to death
Important stressors
Somatic
physical effects: cold, heat, radiation, hypo- and
hyperbaric conditions, noise
pathologic states: hunger, thirst, hemorrhage, physical
exertion, hypoxia, hypoglycaemia,
sepsis;
anaesthesia, surgery
Psychological (typically human)
individual: mental tension, public speech
group:
family troubles, neighbourly stress
social:
work overload, joblessness, go into retirement,
social tension
Tissue
damage
Peripheral
nociceptors
Hypoxemia
Hypercapnea
Chemoreceptors
Hemorrhage
Hypovolemia
Fluid shifts
Arterial baroreceptors
Atrial baroreceptors
Thalamus
Medula
Cardiovascular reflexes
Respiratory reflexes
Systemic inflammation
Fear and Emotion
Thalamus
Leukocytes
Paleocortex
Limbic system
IL-1
PGs
Medulla
Hypothalamus
CRH
Pituitary
CRH
ACTH
Adrenal
Sympathetic efferents
Catecholamines
Cortisol
Essential physiologic actions of adrenergic receptors
1
 glycogenolysis, vascular muscle contraction
2
GIT muscle relaxation, inhibition of insulin secretion
1
 lipolysis, inotropic myocardial effect
2
 release of glucagon and renin, bronchial relaxation
Physiological effects of catecholamines
Cardiovascular system  rate and force of contraction
 peripheral vasoconstriction
Pulmonary system
bronchodilation
Skeletal muscles
 glycogenolysis,  contraction
Liver
 glucose production,  glycogen
Adipose tissue
 lipolysis,  fatty acids and glycerol
GIT
 protein synthesis,  motility
Physiological effects of cortisol
1.
gluconeogenesis, inhibition of the uptake of glucose by
tissues
2.
protein catabolism – muscles, lymphoid tissue, skin,
bone  negative nitrogen balance
3.
promotes lipolysis in some areas of the body
4.
immunosuppressant
Other stress hormones
Endorphins stres-induced analgesia
positive well-being, euphoria
Glucagon
hormone of energy shortage
secretion is stimulated by catecholamines
gluconeogenesis and glycogenolysis
Growth hormone stimulates proteosynthesis and transport
of AA into the muscles
Multiple hormones cooperates to bring about
appropriate metabolic response
1.
Hyperglycemia
a) glycogenolysis and gluconeogenesis in liver
b)  glucose uptake in muscles,  insulin release
 glucose is preserved for CNS
2. Free fatty acids mobilization  metabolised in muscles
Stress and immune system
1.
immune system synthetizes cytokines activating HPA
system
2.
immune cells possess receptors for hormones of HPA
system
3.
stress hormones can influence immune functions
Stress-related diseases and conditions
Cardiovascular system
coronary artery disease
hypertension
arrhythmias
Pulmonary system
hypersensitivity reactions (asthma)
Immune system
immunosuppression or deficiency
GIT system
ulcer, irritable bowel syndrome
Genitourinary system
impotence, frigidity
Skin
eczema
Endocrine system
diabetes mellitus
CNS
fatique, letargy, depression
overeating
insomnia
Increased plasma level of „stress hormones“
Hyperglycemia + hyperlipemia
advantageous for wild animals (fight or flight, starvation)
man supplied with excessive food resources and living usually in
hypodynamic conditions cannot utilise accumulated energetic
substrates  such repeated and long acting situations promote some
pathophysiological states:
 catecholamines
heart dysturbances
 ca + cortisol
hypertension
 rate of coagulation thrombosis
hyperlipidemia
premature atherosclerosis
 glucose utilisation
insulin resistant diabetes mellitus
 protein synthesis
muscular athrophy, osteoporosis
 endorphins
obesity
stress ulcer
dysruption of barrier function and poor perfusion