PHYSIOLOGY: LESSON 1 - Homeostasis, Functional organization of human body, Control of internal environment, Cell Physiology Transport of substances through cell membrane

Question 1 What is the internal environment of the body?

The extracellular fluid (ECF), also called the milieu intérieur.

Question 2 Who introduced the concept of the “milieu intérieur”?

Claude Bernard.

Question 3 What is homeostasis?

Maintenance of relatively constant conditions in the internal environment.

Question 4 Who coined the term “homeostasis”?

Walter Cannon.

Question 5 What percentage of an adult human body is composed of fluid?

Approximately 60%.

Question 6 What are the two major fluid compartments of the body?

Intracellular fluid (ICF) and extracellular fluid (ECF).

Question 7 Which fluid compartment accounts for about two-thirds of total body water?

Intracellular fluid (ICF).

Question 8 Which fluid compartment accounts for about one-third of total body water?

Extracellular fluid (ECF).

Question 9 What are the two major subdivisions of extracellular fluid?

Plasma and interstitial fluid.

Question 10 Which extracellular fluid compartment contains a high concentration of plasma proteins?

Plasma.

Question 11 What is the major cation of extracellular fluid?

Sodium (Na⁺).

Question 12 What are the major anions of extracellular fluid?

Chloride (Cl⁻) and bicarbonate (HCO₃⁻).

Question 13 What is the major cation of intracellular fluid?

Potassium (K⁺).

Question 14 What are the major intracellular anions?

Phosphates and proteins.

Question 15 Why is the extracellular fluid called the internal environment?

Because it surrounds and bathes all cells of the body.

Question 16 How do cells receive oxygen and nutrients?

From the extracellular fluid.

Question 17 How do cells eliminate metabolic waste products?

By releasing them into the extracellular fluid.

Question 18 What are the two stages of transport of extracellular fluid?

Blood circulation and diffusion between capillaries and tissue cells.

Question 19 What mechanism allows rapid exchange of nutrients between plasma and interstitial fluid?

Diffusion across the capillary membrane.

Question 20 Why do plasma proteins remain mainly within the capillaries?

Because they are too large to diffuse through capillary pores.

Question 21 Which organ system supplies oxygen to the body?

The respiratory system.

Question 22 Which organ system absorbs nutrients into the bloodstream?

The gastrointestinal tract.

Question 23 What is the primary function of the liver in homeostasis?

Processing absorbed nutrients and detoxifying harmful substances.

Question 24 Which organ is primarily responsible for regulating electrolyte and water balance?

The kidneys.

Question 25 Which waste product is primarily removed by the lungs?

Carbon dioxide.

Question 26 Which organ system removes urea, uric acid, excess ions, and excess water?

The kidneys.

Question 27 What is the major function of the musculoskeletal system in homeostasis?

It allows movement and protects internal organs.

Question 28 What is the primary function of the integumentary system?

It forms a protective barrier between the internal and external environments.

Question 29 What is the major function of the immune system?

To defend the body against foreign organisms and toxins.

Question 30 What are the three major components of the nervous system involved in regulation?

Sensory input, central nervous system, and motor output.

Question 31 What is the primary role of the autonomic nervous system?

Regulation of involuntary body functions.

Question 32 What is the primary role of the endocrine system?

Regulation of body functions through hormones.

Question 33 Which body system produces hormones that regulate metabolism?

The endocrine system.

Question 34 What is a control system?

A mechanism that regulates body functions to maintain homeostasis.

Question 35 What are the three components of a feedback control system?

Receptor, control center, and effector.

Question 36 What is the function of a receptor in a control system?

Detects changes in the internal or external environment.

Question 37 What is the function of the control center?

Processes information and determines the appropriate response.

Question 38 What is the function of the effector?

Carries out the response to restore homeostasis.

Question 39 What is negative feedback?

A mechanism that opposes the original stimulus to restore normal conditions.

Question 40 What is the most common type of feedback mechanism in the human body?

Negative feedback.

Question 41 Give one example of negative feedback.

Regulation of arterial blood pressure by the baroreceptor reflex.

Question 42 Where are the major arterial baroreceptors located?

The carotid sinus and aortic arch.

Question 43 What happens to baroreceptor firing when arterial blood pressure increases?

It increases.

Question 44 What is the result of increased baroreceptor firing?

Decreased sympathetic activity, lowering blood pressure.

Question 45 What happens when arterial blood pressure decreases?

Baroreceptor firing decreases, increasing sympathetic activity.

Question 46 What is positive feedback?

A mechanism in which the response amplifies the original stimulus.

Question 47 Give one physiologic example of positive feedback.

Blood clotting.

Question 48 Give another physiologic example of positive feedback.

Childbirth (labor contractions).

Question 49 What is the gain of a control system?

The effectiveness of the system, calculated as correction divided by the remaining error.

Question 50 Why is maintaining homeostasis essential for life?

Because cells can survive and function normally only within a relatively constant internal environment.

Question 51 What is the basic structural and functional unit of the human body?

The cell.

Question 52 Approximately how many cells make up the human body?

About 100 trillion cells.

Question 53 What are the three principal parts of a typical cell?

Cell membrane, cytoplasm, and nucleus.

Question 54 What is the primary function of the cell membrane?

It encloses the cell and regulates the movement of substances into and out of the cell.

Question 55 What is the cell membrane primarily composed of?

Lipids, proteins, and carbohydrates.

Question 56 What is the major lipid component of the cell membrane?

Phospholipids.

Question 57 What property of phospholipids allows them to form a bilayer?

They are amphipathic, having hydrophilic heads and hydrophobic tails.

Question 58 Which portion of the phospholipid faces the extracellular and intracellular fluids?

The hydrophilic phosphate head.

Question 59 Which portion of the phospholipid forms the interior of the membrane?

The hydrophobic fatty acid tails.

Question 60 Why is the lipid bilayer relatively impermeable to water-soluble substances?

Because of its hydrophobic core.

Question 61 What is the primary function of cholesterol in the cell membrane?

It stabilizes membrane fluidity and decreases membrane permeability.

Question 62 What are the two major classes of membrane proteins?

Integral proteins and peripheral proteins.

Question 63 What are integral membrane proteins?

Proteins embedded within or extending through the lipid bilayer.

Question 64 What are peripheral membrane proteins?

Proteins loosely attached to the membrane surface.

Question 65 Which membrane proteins commonly function as channels?

Integral membrane proteins.

Question 66 Which membrane proteins commonly function as carriers?

Integral membrane proteins.

Question 67 Which membrane proteins commonly function as receptors?

Integral membrane proteins.

Question 68 What is the glycocalyx?

A carbohydrate-rich coat covering the external surface of the cell membrane.

Question 69 What molecules form the glycocalyx?

Glycoproteins, glycolipids, and proteoglycans.

Question 70 What is one function of the glycocalyx?

Cell-to-cell recognition.

Question 71 What is another function of the glycocalyx?

Cell adhesion.

Question 72 How does the glycocalyx contribute to immunity?

It participates in immune recognition and antigenic properties.

Question 73 What is cytoplasm?

The material between the cell membrane and nucleus.

Question 74 What is cytosol?

The fluid portion of the cytoplasm.

Question 75 What are organelles?

Specialized intracellular structures that perform specific cellular functions.

Question 76 Which organelle is known as the control center of the cell?

The nucleus.

Question 77 What structure surrounds the nucleus?

The nuclear envelope.

Question 78 What allows exchange of materials between the nucleus and cytoplasm?

Nuclear pores.

Question 79 What is chromatin?

DNA associated with histone proteins.

Question 80 What is the nucleolus?

The site of ribosomal RNA synthesis and ribosome assembly.

Question 81 What is the primary function of ribosomes?

Protein synthesis.

Question 82 What organelle synthesizes secretory and membrane proteins?

Rough endoplasmic reticulum.

Question 83 Why is the rough endoplasmic reticulum called “rough”?

Because ribosomes are attached to its surface.

Question 84 What is the primary function of the smooth endoplasmic reticulum?

Lipid synthesis and detoxification.

Question 85 Which organelle modifies, packages, and sorts proteins?

The Golgi apparatus.

Question 86 Where are lysosomes formed?

In the Golgi apparatus.

Question 87 What is the primary function of lysosomes?

Intracellular digestion.

Question 88 Which enzymes are abundant inside lysosomes?

Acid hydrolases.

Question 89 What is autophagy?

The lysosomal degradation and recycling of damaged organelles.

Question 90 What are peroxisomes primarily responsible for?

Oxidation reactions and detoxification.

Question 91 Which enzyme inside peroxisomes breaks down hydrogen peroxide?

Catalase.

Question 92 Which organelle is known as the powerhouse of the cell?

Mitochondria.

Question 93 What is the primary function of mitochondria?

ATP production through oxidative phosphorylation.

Question 94 Which membrane of the mitochondrion contains the electron transport chain?

The inner mitochondrial membrane.

Question 95 What are cristae?

Infoldings of the inner mitochondrial membrane.

Question 96 What is found within the mitochondrial matrix?

Enzymes of the Krebs cycle, mitochondrial DNA, and ribosomes.

Question 97 Why can mitochondria replicate independently?

They possess their own DNA and ribosomes.

Question 98 What are secretory vesicles?

Membrane-bound vesicles that store substances before exocytosis.

Question 99 What is the cytoskeleton?

A network of protein filaments that provides cell shape, support, and movement.

Question 100 What are the three major components of the cytoskeleton?

Microfilaments, intermediate filaments, and microtubules.