Homeostasis Module 1

who said "Homeostasis does not occur by chance but is

the result of organized self-government"

Cannon, 1932

Control Systems

Regulate cellular functions and physical and psychological adaptation to maintain the body's internal environment.

Negative Feedback Systems

Regulate life processes, behaviors, and integrate body systems.

Blood Glucose Regulation

Involves sensors in beta cells that detect blood glucose levels and regulate insulin release.

Decreased Insulin Release

Occurs with an addition of glucose to the blood, leading to an increase in blood glucose levels.

Increased Insulin Release

Occurs with a removal of glucose from the blood, leading to a decrease in blood glucose levels.

Stress (according to H. Selye)

A state manifested by symptoms that arise from coordinated activation of the neuroendocrine and immune systems (General Adaptation Syndrome - GAS)

whats the powerhouse of the stress response

hypothalamus

What is the Sympathetic Nervous System (SNS)?

A part of the autonomic nervous system that prepares the body for stressful or emergency situations, often referred to as the 'fight or flight' response.

What is the Endocrine System?

A system of glands that secrete hormones into the bloodstream to regulate various bodily functions, including the pituitary and adrenal glands.

What is the Immune System?

The body's defense mechanism against infections, diseases, and abnormal cell division, which includes various cells and organs that work together to protect the body.

What is Psychoneuroimmunologic Regulation?

The study of the interactions between psychological processes, the nervous system, and the immune system, highlighting how mental states can affect immune response.

What does 'Psycho' refer to in this context?

It refers to consciousness and mental processes, including thoughts, emotions, and behaviors.

What does 'Neuro' refer to?

It refers to the brain and the central nervous system (CNS), which are responsible for processing information and coordinating bodily functions.

What is Immunology?

The branch of biomedical science that deals with the study of the immune system, focusing on how the body defends itself against disease and abnormal cell division.

Hypothalamus

A region of the brain that plays a crucial role in the stress response by regulating the release of hormones from the pituitary gland.

Adrenal gland

Glands located on top of each kidney that produce hormones such as adrenaline and cortisol, which are involved in the body's stress response.

Locus coeruleus

A small nucleus in the brainstem that is involved in physiological responses to stress and panic, primarily by releasing norepinephrine.

Pituitary gland

A gland located at the base of the brain that regulates various hormonal functions, including the stress response through the secretion of ACTH.

RAS (Reticular Activating System)

A network of neurons in the brainstem that plays a key role in regulating wakefulness and sleep-wake transitions, influencing the stress response.

ANS (Autonomic Nervous System)

A part of the peripheral nervous system that controls involuntary bodily functions and is involved in the stress response by regulating heart rate and digestion.

Brainstem

The part of the brain that connects the brain to the spinal cord and is involved in regulating vital functions, including those related to the stress response.

What is General Adaptation Syndrome (GAS)?

A three-stage response of the body to stress that involves the whole person and is systemic.

What are the three stages of General Adaptation Syndrome?

The three stages are Alarm Reaction, Resistance, and Exhaustion or Recovery.

What occurs during the Alarm Reaction stage?

Arousal begins, and the body releases hormones such as Epinephrine and Norepinephrine in response to a stressor.

What happens during the Resistance stage?

The body attempts to adapt to the stressor and maintain homeostasis.

What are the possible outcomes in the Exhaustion stage?

The onset of disease or recovery, depending on the body's ability to cope with the stressor.

What are stressors?

Events or environmental agents responsible for initiating the stress response.

What does 'endogenous' mean in the context of stressors?

Endogenous refers to stressors that originate from within an individual.

What does 'exogenous' mean in the context of stressors?

Exogenous refers to stressors that come from external forces or the environment.

What is eustress?

Eustress is mild, brief, and controlled stress that can be beneficial and motivating.

What is distress?

Distress is severe, uncontrolled stress that can have negative effects on a person's health and well-being.

Where is the locus coeruleus located?

In the brain stem

What neurotransmitter do neurons in the locus coeruleus produce?

Norepinephrine (NE)

What is the role of the locus coeruleus in the autonomic nervous system?

It is a central integrating site for ANS response to stress

What are the afferent pathways of the LC-NE system connected to?

The hypothalamus, limbic system, hippocampus, and cerebral cortex

What is glycogen?

A stored form of glucose in the body

What hormone does glucagon stimulate?

The conversion of glycogen to glucose

What is glycogenolysis?

The process of breaking down glycogen into glucose

What is gluconeogenesis?

The process of producing glucose from non-carbohydrate sources

What hormones are released by the adrenal gland during SNS activation?

Epinephrine and norepinephrine (cathecholamines)

What receptors are stimulated by catecholamines?

Alpha1, Alpha2, Beta1, and Beta2 adrenergic receptors

What physiological action is associated with Alpha1 receptors?

Increased glycogenolysis and smooth muscle contraction in blood vessels

What is the effect of Alpha2 receptors?

Renin release

What are the effects of Beta1 receptor stimulation?

Stimulation of lipolysis, increased heart rate, and increased force of contraction

What physiological actions are associated with Beta2 receptors?

Increased hepatic gluconeogenesis, glycogenolysis, muscle glycogenolysis, and bronchodilation

What is the chief effect of cortisol during stress?

Promotes gluconeogenesis in the liver and suppresses the immune system

How does cortisol affect the immune system?

Decreases leukocytes at the site of inflammation, delaying healing

What is the role of the hypothalamus in the stress response?

Releases Corticotropin Releasing Factor (CRF) which stimulates the pituitary gland

What does CRF induce the secretion of?

Adrenocorticotropic Hormone (ACTH) from the anterior pituitary gland

What hormone does ACTH stimulate the adrenal cortex to secrete?

Cortisol

What is the function of aldosterone?

Increases sodium absorption by the kidneys

What effect does the sympathetic nervous system have on the cardiovascular system?

Increases heart rate and contractility, and causes blood vessels to constrict

What happens to the bronchioles during SNS activation?

They dilate

What is the effect of the Renin-Angiotensin-Aldosterone System on blood flow?

Decreased blood flow to kidneys triggers renin release

What does renin react with to form angiotensin I?

Angiotensinogen

What converts angiotensin I to angiotensin II?

Angiotensin converting enzyme (ACE) in the lungs

What is the effect of angiotensin II on blood volume?

Increases blood volume by promoting Na+ and H2O reabsorption

What does aldosterone activate in the kidneys?

Na+/K+ pump in distal tubules of nephrons

What is the consequence of K+ loss due to aldosterone?

Increased excretion of potassium

What is the effect of the sympathetic nervous system on the gastrointestinal system?

Can cause irritable bowel syndrome

How does the sympathetic nervous system affect the immune system?

Causes immunosuppression

What is the role of the reticular activating system (RAS) in muscle contraction?

Regulates skeletal muscle contraction

What hormones respond to stress?

Growth Hormone, Thyroid Hormone, Reproductive Hormones, Antidiuretic Hormone (ADH)

What factors impact the response to stressors?

Adaptation, Time, Health Status, Nutrition, Psychosocial factors, Coping mechanisms, Genetics

How is hardiness defined in relation to stress?

It is viewed as having control over the environment and a commitment to life, conceptualizing stressors as challenges rather than threats.

What are common signs and symptoms of acute stress?

Physical signs include increased heart rate; psychological signs may include anxiety and irritability.

What are the effects of chronic stress?

Pathophysiologic changes occur, including increased cortisol levels and various physical and psychological symptoms.

What is Post Traumatic Stress Disorder (PTSD)?

Chronic activation of the stress response due to experiencing a potentially life-threatening event.

What are the clusters of symptoms for PTSD?

Intrusion, Avoidance, Hyperarousal

What are non-pharmacological agents to decrease stress?

Debriefing, Counseling, Relaxation, Meditation, Music Therapy, Biofeedback, Imagery

What is thermoregulation?

It is the balance between heat gain and heat loss by the body, regulated by the hypothalamus.

What methods are used for heat loss?

Radiation, Conduction, Convection, Evaporation

What factors affect core temperature?

Conservation of heat (vasoconstriction, shivering) and heat loss (vasodilation, sweating).

What are methods of obtaining a core temperature?

Rectal thermometer, esophageal thermometer, pulmonary artery catheter, urinary catheter with thermosensor.

What are pyrogens?

Substances that produce fever; exogenous pyrogens come from outside the body, while endogenous pyrogens are produced by the host.

What is an intermittent fever pattern?

Temperature returns to normal at least once every 24 hours.

What is a remittent fever pattern?

Temperature does not return to normal and varies in either direction.

What is a sustained or continuous fever pattern?

Temperature remains above normal with minimal variations.

What is a relapsing fever pattern?

One or more episodes of fever lasting several days with normal temperature between episodes.

What physiologic behaviors occur during fever?

Prodrome (mild headache, fatigue), Chills (sensation of being chilled), Flush (cutaneous vasodilation), Defervescence (initiation of sweating).

What is the significance of homeostasis in stress response?

It relates to the body's ability to maintain stable internal conditions despite external changes.

What is the role of control systems in stress response?

They involve negative feedback mechanisms that regulate bodily functions during stress.

Who is associated with the General Adaptation Syndrome (GAS)?

Hans Selye, who described the body's response to stress.

What are the signs and symptoms related to chronic and acute stress?

They include physical symptoms like fatigue and psychological symptoms like anxiety.

What are some treatment methods for stress?

Relaxation techniques, counseling, and lifestyle changes.

What is the role of the autonomic nervous system (ANS) in stress response?

It regulates involuntary physiological responses during stress.