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What is the primary function of brown adipose tissue?

Regulation of body temperature by generating heat (correct)

Secretion of hormones for metabolic control

Enhancement of insulin sensitivity

Storage of lipids for energy

How does hypoxia affect human adaptation mechanisms?

Reduces the efficiency of the immune system

Inhibits growth and development

Decreases metabolic rates

Increases the production of red blood cells (correct)

Which component of the immune system is primarily responsible for identifying and destroying infected cells?

Natural killer cells

Macrophages

B cells

T cells (correct)

What does the hygiene hypothesis suggest about the rise of allergies and autoimmune diseases?

Increased exposure to microbes improves immune function Signup and view all the answers

What type of relationship do humans share with their microbiota?

Mutualism Signup and view all the answers

What is one possible outcome of intergenerational inheritance of health?

Health risks can be influenced by prenatal exposures Signup and view all the answers

In terms of adaptation, what is homeostasis?

The process of balancing physiological functions Signup and view all the answers

Which model emphasizes the influence of prenatal and environmental factors on health?

Developmental Origins of Health and Disease (DOHaD) Signup and view all the answers

What is the primary function of brown adipose tissue in humans?

Regulation of body temperature by burning calories Signup and view all the answers

Which of the following describes a common effect of hypoxia on the human body?

Adaptation through increased erythropoietin production Signup and view all the answers

Which component is not typically part of the immune system?

Neurons Signup and view all the answers

What does the hygiene hypothesis suggest regarding immune system development?

Increased exposure to pathogens reduces allergies Signup and view all the answers

What is a primary benefit of symbiotic relationships in human microbiota?

Enhanced digestion and nutrient absorption Signup and view all the answers

Which adaptation occurs over decades as a response to environmental conditions?

Genetic adaptation Signup and view all the answers

Which of the following modes of adaptation involves changes that occur during the early stages of life?

Developmental adaptation Signup and view all the answers

What limits the allocation of energy in most organisms?

Finite total energy budget Signup and view all the answers

What is the primary role of brown adipose tissue during acclimatization to cold stress?

Production of heat through non-shivering thermogenesis Signup and view all the answers

What is one major effect of hypobaric hypoxia?

Decreased barometric pressure leading to fewer oxygen molecules Signup and view all the answers

Which component of the immune system provides the first line of defense against infections?

Phagocytic cells Signup and view all the answers

What is a potential implication of the Hygiene Hypothesis?

Altered immune responses to non-harmful substances Signup and view all the answers

Which relationship is characterized by both species benefiting from their interaction?

Symbiotic relationship Signup and view all the answers

What physiological change is commonly observed in people acclimatized to high altitudes?

Increased hemoglobin concentration Signup and view all the answers

Which immune response feature is unique to adaptive immunity?

Memory of previous infections Signup and view all the answers

Which of the following is a common example of an autoimmune disease?

Celiac Disease Signup and view all the answers

In the context of immune functions, how does the gut microbiota contribute?

Breaking down nutrients Signup and view all the answers

How could the Hygiene Hypothesis potentially explain the rise of certain allergic diseases?

By making the immune system more reactive to harmless substances Signup and view all the answers

What happens to the brown adipose tissue during cold exposure?

It activates to enhance heat production Signup and view all the answers

Which type of immunity is responsible for a specific response to a pathogen?

Adaptive immunity Signup and view all the answers

What defines a commensal relationship?

One species benefits and the other is neither harmed nor helped Signup and view all the answers

What is a typical symptom of chronic mountain sickness?

Headache and breathlessness Signup and view all the answers

What is the function of the microbiome-gut-brain axis?

Facilitates communication between microbiota and the brain Signup and view all the answers

Study Notes

Lecture 20: Exam 2 Review

Innate immune system question on exam
Options for innate immune system component: T Lymphocytes, B Lymphocytes, Mucosal Membrane, Antigens
Correct answer: Mucosal Membrane

Lecture 12: Historical Perspectives on Human Variation and Race

Immanuel Kant
Ethnocentrism
Scientific racism
Polygenism vs. Monogenism
Typology
Eugenics
Anthropometry
Franz Boas
Plasticity
Cline
Tuskegee Study of Untreated Syphilis

European Colonialism and Documenting Human Variation

European explorers documented and described people and environments since the 1600s
Ethnocentrism is the tendency to view one's own culture as best and judge others by one's own standards

Early Writings on Race - Immanuel Kant (1724-1804)

Known for his contributions to philosophy
During his lifetime, he categorized humanity by skin color and hair texture
Believed these categories corresponded to behavioral and physical traits
Believed the aesthetics and other traits of white people were superior

Polygenism vs. Monogenism

Polygenism: Doctrine that human races were separate biological species descended from different "Adams"
Monogenism: Doctrine that human races shared a single origin

Typology, Science, and Racism

Typology is a method to reduce variation to smaller categories based on "ideal" types.
Anthropometrics are measurements of the human body, head, and face used to distinguish racial groups.
Problem with anthropometrics: influenced by environment and independently inherited. Clinal distribution pattern.
Eugenics: Movement that tried to improve the human species via planned breeding

Lecture 13: Contemporary Perspectives of Human Variation

Genetic determinism
Racial inequalities in health
Racial-Genetic determinism
3 critiques of racial-genetic determinism
Embodiment
Morbidity
Mortality

What We Know Today

Races cannot be defined based on gene incidence
Greater genetic diversity within groups than between geographical divisions
Race is socially constructed, not biologically determined

First, a Few Key Definitions – Race

A recent idea created by Western Europeans to account for human differences
Used to justify colonization, conquest, enslavement and social hierarchy.
Associated with perceived biological markers

First, a Few Key Definitions – Ethnicity

Similar to race, it groups people based on common origins/backgrounds
Usually refers to social, cultural, religious, linguistic and other affiliations.

Explaining Human Genetic Diversity

Most human genetic diversity evolved in Africa
Genetic diversity outside Africa is a subset of what exists within Africa due to founder effect and genetic drift

3 Main Critiques of Race as a Genetically Determined Category

Human genetic variation is clinal
Most human genetic variation is discordant (traits are independently inherited and don't predict other biological aspects)
Human genetic variation is widely shared.

What about Genetic Ancestry Tests?

Perpetuate the idea that genes alone define who we are.
Genetic determinism: belief that genetic contributions are more important than other factors such as epigenetic and environmental ones

Embodiment (Krieger 2005): Concept of how our social world influences our biology from conception to death

Lecture 14: Human Energetics

Social Determinants of Health Model
Intergenerational Inheritance of Health Model
Adaptation
Timescales of Adaptation Model
Homeostasis
Allostasis
Acclimatization
Developmental adaptation
Genetic adaptation
Human Energy Allocation Model
Metabolic health
Adipose tissue: Subcutaneous and visceral
Food security

Diagram showing factors influencing health outcomes, including economic stability, neighborhood environment, education, food, community and social context, and health care systems

Intergenerational Inheritance of Health Model

Model influenced by Developmental Origins of Health and Disease (DOHaD)
Prenatal and infant exposures to environmental conditions can influence disease risk in adulthood

The International Biological Program and the Human Adaptability Project

Large-scale, international collaboration studying human adaptability and ecological interactions.

What is biological adaptation?

Process of change in physiology or morphology resulting from an altered environment.
Improves evolutionary fitness (survival and reproduction).
Depends on the degree and timing of exposure

Timescales of Adaptation Model

Allostasis = rapid changes in physiology to regulate internal biology.
Acclimatization = physiological changes occurring over days to weeks responding to a new environmental condition.
Developmental adaptation = changes in development responding to environmental conditions that improve fitness.
Genetic Adaptation = Adaptations to environmental conditions arising through natural selection and are heritable.

Human Energy Allocation Model

Total energy budget is finite and allocated across competing biological functions (basal metabolism, growth and reproduction, maintenance)

What is Metabolic Health?

Risk of developing cardiovascular disease or type II diabetes
Poor metabolic health is characterized by hypertension (systolic/diastolic blood pressure)

Metabolic Health and Adipose Tissue

Subcutaneous adipose tissue (SAT) is distributed on hips, thighs and buttocks; produces fewer inflammatory molecules.
Visceral adipose tissue (VAT) is closer to organs; produces more inflammatory molecules.

Epidemiological Transition

Shift from infectious diseases to non-infectious diseases as primary causes of mortality.
Pre-transition society: high death rate from epidemics and childhood infectious diseases. Low life expectancy.
Post-transition Society: improved sanitation, public health, and medical technology reduce infectious disease rates, allowing chronic diseases to become primary cause of death. Increased life expectancy

Lecture 15: Psychosocial Stress

Epidemiological transition
Homeostasis
Allostasis
Stressor
Acute vs chronic stress
Autonomic nervous system
Sympathetic nervous system
Parasympathetic nervous system
Neurotransmitter
Hormone
HPA axis
Cortisol

What is stress?

Homeostasis: Steady internal physical/chemical conditions maintained by living systems.
Allostasis: Regulation of internal biology through rapid physiological changes; recognizes that the optimal set-point is context dependent.
Stressor: Any environmental trigger that leads to the allostatic response.

Characteristics of the Acute Stress Response

Rapid mobilization of energy (body fat).
Inhibition of future energy storage and food digestion.
Increased breathing rate, blood pressure and heart rate to improve nutrient and oxygen transport.
Halt energy-expensive processes (growth, reproduction, tissue repair).

The Autonomic Nervous System

Regulates unconscious bodily functions like heart rate, blushing, goosebumps, digestion, etc.
Sympathetic Nervous System (SNS): activated by stress.
Parasympathetic Nervous System (PNS): turned off by stress.

Sympathetic Nervous System

Controls “fight or flight” response.
Produces the hormones epinephrine/norepinephrine.
Releases neurotransmitters over short distances.

Hypothalamus-Pituitary-Adrenal (HPA) Axis

Brain processes psychosocial stress, causes the release of CRH.
CRH travels to the pituitary gland.
Pituitary gland releases ACTH.
ACTH travels to the adrenal glands.
Adrenal glands produce glucocorticoids (like cortisol), which have metabolic effects.

Cortisol: a stress hormone and a metabolic hormone

Increased blood glucose levels, suppresses the immune system, affects metabolism, decrease bone formation.
Has a diurnal rhythm (pattern of levels over the day or night).

Lecture 16: UV Adaptations

Melanin and its function
Melanocyte
Pheomelanin
Eumelanin
Ultraviolet radiation (UVR)
MC1R gene
Folate
Vitamin D
Tanning response

Risks and Benefits of UVR Exposure

Risks: Sunburn, premature aging, skin cancer, eye diseases
Benefits: Vitamin D production
Vitamin D helps absorb calcium and phosphorus for bone growth/maintenance

Melanin and Its Function

Melanin: 3 types- eumelanin (black/brown), pheomelanin (reddish), neuromelanin (in neurons).
Function: UV protection by absorbing UVA, UVB, UVC and blue light, protecting deeper skin cells from damage.

Tanning Response

Skin produces eumelanin due to seasonal high UVR exposure.
Outcome of UV-induced stress.
Regulated by melanocortins.
Minimal photoprotection from natural UVB tans.
UVA tans offer no protective benefit.

Lecture 17: Biological Adaptations to Cold Climates

Allen's rule
Bergmann's rule
Vasoconstriction/vasodilation
Thermogenesis
Non-shivering thermogenesis
Brown adipose tissue
Acclimatization to cold stress
Hunting's response
Developmental adaptations to cold stress

Biological Adaptations to Cold Stress

Preventing heat loss: Body composition, Body Morphology, Vasoconstriction
Generating heat (Thermogenesis): Elevated BMR, Shivering, Non-shivering Thermogenesis (NST)

Body Proportions and Climate - Bergmann's Rule

Larger animals are adapted to colder climates due to increased efficiency in heat retention.
Smaller animals are adapted to warmer climates for better heat dissipation.

Body Proportions and Climate - Allen's Rule

Animals in warm climates have longer limbs to increase heat loss compared to animals in cold environments with reduced limb length.

Brown Adipose Tissue (BAT)

Specialized tissue generating heat, involved in cold acclimatization in humans and some mammals.

Acclimatization to Cold Stress

Reduced shivering threshold, faster initiation of non-shivering thermogenesis.
Alternating vasoconstriction and vasodilation.
Increased basal metabolic rate (BMR).
Increase in thyroid hormone production.
Increased tissue uptake from circulation.
Increase in brown adipose tissue (BAT).

Lecture 18: Biological Adaptations to Hypoxia

Acute and chronic mountain sickness
Hypobaric hypoxia
Candidate genes
Genome-wide association study
Oxygen transport
Hypoxic ventilatory response
Vital capacity
Residual volume

Hypobaric Hypoxia

Reduced atmospheric pressure at high altitudes leads to lower oxygen concentrations in air.

Various illnesses at different altitudes: AMS, HACE, HAPE
Order of severity: AMS, HACE, HAPE

Chronic Mountain Sickness

Well-adapted residents can lose adaptation and become ill.
Symptoms: Headache, breathlessness, fatigue, insomnia, confusion.
Risk Factors: Male, over 50 years old, overweight.

Oxygen Transport in Andean and Tibetan Highlanders

Andean highlanders exhibit high lung capacity due to high VC. Also high hemoglobin concentration.
Tibetan highlanders exhibit high blood flow to brain/extremities. Also elevated hypoxic ventilatory response.

Lecture 19: Immune Function, Hygiene Hypothesis, and Microbiome

Immune system
Innate immunity
Adaptive immunity
Antigen
Autoimmune disease
Hygiene hypothesis
Microbiota
Commensal relationship
Symbiotic relationship
Pathogenic relationship
Gut microbiota functions

The Immune System

Host defense system comprising biological structures and processes.
Protects from infectious disease.
Consists of innate and adaptive immunity.

Innate Immunity

Defenses not dependent on prior exposure to disease.
First line of defense against infection and injury
Examples include mucosal membranes, antimicrobial proteins, phagocytic cells (like neutrophils), and inflammatory response.

Adaptive Immunity

Acquired or specific immunity.
Depends on prior exposure to antigens.
Characterized by specificity, diversity, and memory.
Includes T and B lymphocytes.

Autoimmune Disease

Abnormal immune response to normal body parts
Examples include celiac disease, type 1 diabetes, Graves' disease, inflammatory bowel disease, multiple sclerosis, rheumatoid arthritis.

Hygiene Hypothesis

All living things evolved with parasite exposure
Early life bacterial and viral infections are important for immune maturation.
Lack of infections in developed countries due to hygiene/antibiotics may cause immune system reactions to innocuous substances.

Riddled with Life: Friendly Worms, Ladybug Sex, and the Parasites that Make Us Who We Are

Treating Crohn's Disease with worms
Worms stimulate the Th-2 response to regulate Th-1 activity.
Malfunctioning Th-1 response is characteristic of Crohn's disease.
Hypothesis: Infecting with pig whipworms can regulate Th-1 activity for treating Crohn's Disease

Microbiota

Ecological communities of commensal, symbiotic, and pathogenic microorganisms.
Commensal: one species benefits, other is unaffected
Symbiotic: both species benefit
Pathogenic/parasitic: one species benefits, other is harmed.

Functions of the Gut Microbiota

Immune function: Maintaining immunological balance through cross-talk with the immune system.
Metabolism: Breaking down/absorbing nutrients, particularly carbohydrates.
Communication with the brain: Microbiome-gut-brain axis, with biochemical signals influencing brain function.

Exam 2 Information (Summary)

Dates and details for Exam 2 (review session, exam date)
Also includes the start date for Unit 3 (human life history)

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