Topic 6

Question 1

Homeostasis

Answer 1

Homeostasis is the maintenance of a constant internal environment within physiological tolerance limits. A disease will occur if a factor is not within its normal range. Physiological processes are regulated by negative feedback.

Question 2

Appetite Control

Answer 2

Appetite suppression is regulated by the hormone called leptin. Adipose cells secrete leptin in order to suppress appetite. Leptin binds to receptors located in the hypothalamus.

Question 3

Pneumocytes

Answer 3

Type I pneumocytes: Involved in gas exchange between alveoli and capillaries. Are extremely thin (minimises gas diffusion distances)

Type II pneumocytes: Responsible for the secretion of pulmonary surfactant. This creates a moist surface that reduces surface tension (prevents sides of alveoli from adhering to each other).

Question 4

Pathogens

Answer 4

Pathogens are disease-causing agents that disrupt the normal
physiology of infected organisms ex. homeostatic imbalance. Pathogens may be species-specific or cross species barriers. Diseases that can be naturally transmitted between animals and humans are called zoonotic diseases.

Question 5

Coronary Heart Disease (CHD Risk Factors)

Answer 5

Genetics (ex. hypertension)
Obesity (overweight = risk)
Diseases (ex. diabetes)
Diet (ex. increased trans fats)
Exercise (inactivity = risk)
Smoking (increased blood pressure)
Sex (males = higher risk)

Question 6

Membrane Transport Mechanisms

Answer 6

Secondary Active Transport-Glucose and amino acids are co-transported across the membrane with sodium ions (Na+).
Facilitated Diffusion-Certain monosaccharides, vitamins and some minerals may be transported by the channel proteins.
Simple Diffusion- Hydrophobic materials (ex. lipids) are capable of freely diffusing across the epithelial membrane.

Question 7

Digestion Types

Answer 7

Mechanical Digestion-The breakdown of food via physical actions.
* Chewing (grinding food using teeth)
* Churning (squeezing stomach contents)
* Segmentation (intestinal contractions)
Chemical Digestion-The breakdown of food via chemical agents.
* Stomach acids (low pH environment)
* Bile (emulsification of fats into droplets)
* Enzymes (catalyse hydrolysis reactions)

Question 8

Nervous System

Answer 8

The nervous system consists of two main divisions: Central nervous system (CNS) which is the brain and spinal cord, and the peripheral nervous system (PNS) which are peripheral nerves.
The nervous system is composed of specialised cells called
neurons that function to transmit electrical signals.The CNS coordinates sensory & motor signals from the PNS. Sensory neurons send signals to the CNS (afferent pathway). Motor neurons send signals from the CNS (efferent pathway). Relay neurons (interneurons) send signals within the CNS.

Question 9

Role of Hormones in the menstrual cycle

Answer 9

Pituitary Hormones (FSH and LH): Stimulate follicular growth within the ovaries, stimulate estrogen secretion (from the ovarian follicles), stimulate progesterone secretion (from corpus luteum), and a surge in LH triggers ovulation (egg release).

Ovarian Hormones (estrogen and progesterone): Promote development and thickening of the endometrium, promote FSH / LH secretion during the follicular phase, and inhibit FSH / LH secretion during the luteal phase.

Question 10

Myelination

Answer 10

Nerve impulses are action potentials propagated through axons. Action potentials are only propagated if a certain threshold potential is reached (~ -55mV)
In certain neurons, the axon is covered by a myelin sheath. This sheath enables saltatory conduction (increased transmission speed). The action potential jump between gaps in the myelin sheath (called nodes of Ranvier) for faster transmission.

Question 11

Causes of lung cancer

Answer 11

Most causes for lung cancer are typically radiation, aging, pollution, environment, diseases, genetics, occupation, asbestos, tobacco, and smoke.

Question 12

Symptoms of lung cancer

Answer 12

Respiratory distress, weight loss, wheezing, and coughing up blood.

Question 13

Definition of Epidemiology

Answer 13

Epidemiology is the study of distributions and determinants of health related issues.

Question 14

Function of veins

Answer 14

The purpose of veins is to collect poorly oxygenated blood, and carry it back to the heart.

Question 15

Function of Pocket Valve

Answer 15

They allow for the exit of blood from the heart through these valves that follow ventricular contractions.

Question 16

Definition of Gas Exchange and Ventilation

Answer 16

Gas Exchange- The movement of oxygen from your lungs to your bloodstream.

Ventilation- The process of breathing within an organism that allows for gas exchange.

Question 17

Gas Exchange location

Answer 17

Gas exchange occurs in the alveoli which is located at the end of the bronchiole within the lungs.

Question 18

Causes of Emphysema

Answer 18

Emphysema is caused by smoking because it causes damage to the alveolar walls.

Question 19

Symptoms of Emphysema

Answer 19

Symptoms of emphysema include: Mucus production, chronic cough, wheezing, shortness of breath, tightness in chest.

Question 20

Treatments of Emphysema

Answer 20

Symptoms of Emphysema include bronchodilators, corticosteroids, enzyme inhibitor, oxygen supplementation, surgery and sometime medications.

Question 21

Mechanism of neuron depolarization

Answer 21

Sodium Ion channels open within the plasma membrane.

Question 22

Mechanism of neuron repolarization

Answer 22

Potassium Ion channels open in the plasma membrane.

Question 23

Definition of Nerve Impulse

Answer 23

Action potentials that are propagated along the axons of neurons.