Nutrition Module: Zinc & Copper Overview

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Questions and Answers

What is a key biological role of copper in the body?

It contributes to metabolic processes. (correct)

It regulates blood sugar levels.

It helps in fat storage.

It aids in protein digestion.

What are the risks associated with inadequate copper levels?

Deficiency-induced neurological issues. (correct)

Reduced energy consumption.

Increased absorption of iron.

Enhanced bone density.

Which of the following statements about copper is true?

Copper has both toxicity and deficiency risks. (correct)

Copper is unnecessary for metabolic functions.

Copper is associated solely with heart health.

Copper absorption does not vary by food type.

Which pathway is involved in the absorption of copper in the body?

Primarily through transport proteins in the small intestine. Signup and view all the answers

Why is copper considered critical for neurological health?

It supports myelin formation and neurotransmitter function. Signup and view all the answers

What is the normal range for blood zinc levels in μg/100ml?

120 - 140 Signup and view all the answers

Which protein in the blood is zinc associated with?

Albumin Signup and view all the answers

How does zinc influence system functions in the body?

Its functions are dependent on various organ and protein levels. Signup and view all the answers

Why is zinc considered important for human health?

It supports the function of most body systems. Signup and view all the answers

What can be inferred about zinc levels and health?

Adequate zinc levels are essential for proper bodily function. Signup and view all the answers

What role do metallothioneins (MTs) play in the presence of physiological heavy metals?

They regulate cell growth and protect against oxidative stress. Signup and view all the answers

Which heavy metals are specifically mentioned as being bound by metallothioneins?

Cadmium, mercury, zinc, and copper. Signup and view all the answers

What can happen to zinc as a result of metallothioneins trapping it within epithelial cells?

It may be lost to feces when the cells are sloughed off. Signup and view all the answers

What is one potential consequence of excessive binding of heavy metals by metallothioneins?

Loss of essential nutrients like zinc. Signup and view all the answers

In what way do metallothioneins offer protection in a physiological context?

By trapping heavy metals and regulating their effects. Signup and view all the answers

What is the primary defect associated with poor intestinal Copper absorption?

Absence of Copper binding ATPase Signup and view all the answers

Which mechanism is impaired due to the absence of Copper binding ATPase?

Transport of Copper across the Serosa Signup and view all the answers

Which of the following consequences may result from defective intestinal Copper absorption?

Copper deficiency Signup and view all the answers

What cellular component is specifically implicated in the process of Copper absorption?

Copper binding ATPase Signup and view all the answers

In the context of Copper absorption, what does 'Serosa' refer to?

The outer membrane of a mucosal cell Signup and view all the answers

What is the primary cause of acrodermatitis enteropathica?

Mutations in the ZIP4 gene Signup and view all the answers

Which mineral absorption is severely affected in individuals with acrodermatitis enteropathica?

Zinc Signup and view all the answers

What role does the ZIP4 gene play in the human body?

Facilitating zinc transport Signup and view all the answers

What impact does acrodermatitis enteropathica have on health?

It highlights the importance of zinc transport mechanisms Signup and view all the answers

Which statement about acrodermatitis enteropathica is true?

It is caused by genetic mutations impacting zinc absorption Signup and view all the answers

Which enzyme is NOT mentioned as containing copper?

Catalase Signup and view all the answers

What function does copper play in collagen synthesis?

It facilitates the formation of cross-links in collagen. Signup and view all the answers

Which of the following is NOT a role of copper in the body?

Regulating blood sugar levels Signup and view all the answers

Which of the following enzymes is specifically involved in combating oxidative stress and contains copper?

Superoxide dismutase Signup and view all the answers

How does copper contribute to enzyme function in the body?

By acting as a prosthetic group in enzymatic reactions Signup and view all the answers

Study Notes

University of Baghdad, College of Medicine, 2024-2025

Location: Baghdad, Iraq
Academic year: 2024-2025
Course title: Minerals (Zinc & Copper)
Grade level: Third
Module title: Nutrition, Water & Electrolytes Imbalances (NT)
Lecturer: Dr. Thikra Hasan Mathkor
Date of lecture: 22/10/2024

Objectives

Analyze zinc distribution, absorption mechanisms, biological functions, potential deficiency/toxicity levels, and roles in enzymatic/immune function.
Examine copper distribution, absorption pathways, biological significance, associated deficiency/toxicity risks, and contributions to metabolic/neurological health.

Zinc in Human Body

Primarily an intracellular element.
Recommended daily allowance (RDA) for adults: 10-15 mg/day
Distribution: skeletal muscle (60%), bone (30%), skin (5%), other tissues (brain, kidney, pancreas, heart) (5%), plasma (~0.1%).

Zinc Absorption

Facilitated by low molecular weight zinc-binding factors produced by the pancreas (zinc importers/transporters, ZIPs and ZnTs).
Interfered with high amounts of dietary calcium, phosphorus, and phytates.
Blood zinc levels: 120-140 µg/100ml
Associated with albumin in blood.
Losses occur through faeces, sweat, urine, seminal fluid.

Zinc Functions

Broadly spread throughout the body, influencing organ, cellular, and protein function.
Essential for many systems, including immunity (T&B cells, antibody production), metabolism (insulin storage/secretion, receptor function), other sensory function (night vision, taste, olfaction), cardiovascular health (blood pressure, mucociliary clearance).

Zinc Enzymes

RNA polymerase: Transcription, synthesis of mRNA
Carboxypeptidase A: Protein digestion in intestine
Protein kinase C: Signal transduction
Carbonic anhydrase: Respiration (buffering/hydration of CO2)
Cytochrome c oxidase: Respiration/electron transport chain
Alcohol dehydrogenase: Ethanol metabolism
Superoxide dismutase: Inactivation of free radicals
Nitric oxide synthase: Signaling, vasodilation
Angiotensin converting enzyme: Blood pressure regulation

Zinc Transcription Factors

Many zinc enzymes and transcription factors utilize zinc atoms coordinated by cysteine/histidine residues to stabilize DNA-binding.
Some factors are important in the biological response to various signals, such as hormones.

Metallothioneins (MTs)

A family of proteins involved in metal ion homeostasis and detoxification, rich in sulfhydryl groups.
Found in liver, kidney, and intestine.
Bind to physiological heavy metals (cadmium, mercury, zinc, and copper) to regulate cell growth, proliferation, and offer antioxidant protection.
Can trap zinc, leading to loss in feces as epithelial cells shed.

Enteric Zinc and Copper Absorption

Normal absorption involves metallothionein activity.
Excess zinc increases metallothionein production, binding copper and transporting it back to the gut for excretion.

Acrodermatitis Enteropathica

Congenital malabsorption of zinc.
Autosomal recessive disorder
Causes severe zinc deficiency.
Defects in the zinc transporter gene (ZIP4) localized to the apical membrane of intestinal epithelial cells.
Manifestations: skin inflammation, around orifices, tips of fingers and toes, diarrhea, hair loss, growth retardation, anorexia, and crying.

Copper Absorption

Copper-transporting ATPases (ATP7A and ATP7B) are critical in intestinal absorption and biliary excretion.
Dysfunction of ATP7A and ATP7B underlies Menkes and Wilson's disease.
Copper can be stored in metallothionein or incorporated into ceruloplasmins in the liver.
Circulating ceruloplasmin plays a role in iron metabolism and transport.

Copper’s role in enzymes

Cytochrome oxidase
Phenol oxidase/uricase
ALA synthase
Ascorbic acid oxidase
Catalase
Tyrosinase
Superoxide dismutase
Monoamine oxidase

Copper Function & Role in Hemoglobin

Essential for hemoglobin synthesis.
Needed for ALA synthase, a molecule used in heme synthesis.
Essential in elastin and collagen synthesis.

Copper and L-Tyrosine in Melanin Synthesis

Tyrosinase activity, with copper in the active center, catalyzes L-Tyrosine's conversion to L-Dopaquinone, an important step in melanin synthesis.

Copper Role in Iron Metabolism

Ceruloplasmin, a copper-dependent oxidase, plays a role in oxidizing ferrous iron (Fe2+) to ferric iron (Fe3+).
Crucial for iron transport in the blood via transferrin.

Copper-containing non-enzymatic proteins

Hepatocuprein
Hemocuprein
Cerebrocuprein

Copper Deficiency

Reduced transferrin/ferritin saturation.
Lower Hb concentration/oxygen supply to tissues.
Decreased ATP production.
Directly/indirectly affects iron metabolism, heme biosynthesis (weakness, weight loss), iron deficiency anemia, melanin/collagen biosynthesis (demyelination/bone disorder).

Menkes Disease

Inherited X-linked disorder affecting only males.
Defect in copper absorption in the intestine.
Defective transport of copper across the serosal membrane.
Clinical manifestations: kinky hair, mental retardation, abnormal bone formation, susceptible to infections.

Wilson's Disease

Autosomal recessive disorder.
Increased copper absorption.
Reduced/defective copper excretion in bile.
Accumulation of copper in the liver, brain/nervous system and other tissues.
Clinical manifestations: Hepatic cirrhosis, brain necrosis, neurological problems, Kayser-Fleischer rings(rings in the cornea).

Copper Toxicity Treatment

Penicillamine (DP): Used to excrete copper through the urine and is a preferred standard of therapy for Wilson's disease.
Treatment involves chelation therapy for excessive copper accumulation by sequestering the metal, rendering it nontoxic.

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Description

This quiz covers the essential aspects of zinc and copper in human nutrition, focusing on their distribution, absorption mechanisms, and biological functions. It aims to analyze potential deficiencies and toxicities associated with these minerals, which are crucial for enzymatic and immune functions. Suitable for third-year medical students in the College of Medicine.