HUBS 191 FINAL EXAM QUESTIONS AND ANSWERS

HUBS 191 FINAL EXAM QUESTIONS AND ANSWERS Name the four basic types of tissue -Answer-Connective tissue, epithelial tissue, muscle tissue and nervous tissue. Why do the four types of tissues have different structures and function? -Answer-They are made up of different kinds of cells. They have different things that make up the extracellular matrix. They have varying amounts of extracellular matrix. Types of connective tissue -Answer-Connective tissue proper - Loose connective tissue which keeps organs and epithelia in place. - Dense connective tissue forms ligaments and tendons. - Adipose tissue (fat) and reticular connective tissue (support lymph organs like the lymph nodes) Specialised connective tissue - Blood, bone and cartilage Main role of connective tissue -Answer-- Transport substances - Provide support and structure Features of epithelial tissue -Answer-- Tightly packed cells - Little extracellular matrix - Forms skin and lines internal cavities - Many glands are made of epithelial tissue Features of muscle tissue -Answer-- Cells are stretched or fibre-like - Main role is contraction - Allows body and its organs to move - Cardiac muscle, skeletal muscle, smooth muscle. Nervous Tissue -Answer-- Made up of neurons (conduct messages) and glia (support and protect nervous system) - Main role is to transmit electrical signals allowing for communication and coordination. Cells only survive if the following conditions are meet -Answer-- Enough nutrients - Correct temprature - Correct pH - Can only tolerate smal amounts of toxic substance and waste. This is why maintaining a constant internal environment (homeostasis) is so important, along with exchange of nutrients and wast across the cell membrane. Total body fluid numbers to memorise -Answer-2/3 of total body fluid is intracellular fluid (ICF) 1/3 of total body fluid is extracellular fluid (ECF) 4/5 or 80% of extracellular fluid is interstitial fluid (between cells). 1/5 or 20% of extracellular fluid is plasma (50% of total blood volume). What are transcellular fluids? -Answer-ECF also includes various 'transcellular fluids' contained within epithelial lined spaces e.g. synovial fluid in joints, ocular fluid in the eye, cerebrospinal fluid What does a unicellular organism depend on its immediate environment to provide? - Answer-Nutrients Solute concentration Temperature pH Toxins (including own wastes) Lack of Predators This limits the environment a unicellular organism is able to survive. What is 'milieu interieur' -Answer-Claude Bernard () recognised the importance of the body's internal environment or extracellular fluid. The constancy of the internal environment is the condition for a free and independent life. How did Walter Bradford Cannon () define homeostasis? -Answer-The maintenance of relatively constant conditions in the internal environment (ECF) in the face of external (or internal) change. 1. In our bodies there are mechanisms that act to maintain constancy. 2. Any tendency toward change automatically meets with factors that resist change. 3. There are co-operating mechanisms which act simultaneously or successively to maintain homeostasis 4. Homeostasis does not occur by chance, but is the result of organised self- government. Normal concentration of sodium (Na+) in the ECF and why it needs to be controlled. - Answer-Normal concentration in ECF is about 135 - 145 mmol/L. Main extracellular cation. Largely determines extracellular fluid volume so also influences blood pressure (BP). Important in action potential generation in nerve and muscle tissue. Normal concentration of calcium (Ca+) in the ECF and why it needs to be controlled. - Answer-Normal total plasma conc. is about 2.2 - 2.6 mmol/L. Important structural component of bone and teeth. Involved in neurotransmission and muscle contraction. Essential for blood clotting. Regulates enzyme function. Normal concentration of potassium (K+) in the ECF and why it needs to be controlled. - Answer-Normal concentration in ECF is about 3.5 - 5 mmol/L. Most abundant intracellular cation. Main determinant of the resting membrane potential (RMP). Particularly important in excitable tissue i.e. nerve and muscle. Normal concentration of glucose in the ECF and why it needs to be controlled. -Answer- Normal fasHng glucose concentration ≈ 3.5 - 6 mmol/L. Non fasting (random) ≈ 3.5 - 8 mmol/L Used by cells (especially neurons) to produce adenosine triphosphate (ATP). Neurons particularly affected by low glucose levels. High blood glucose causes other problems both acute and chronic. Normal pH range and conditions that result in pH being outside of the normal range. - Answer-Normal pH range is 7.35 - 7.45.