Homeostasis, Body Systems & Non-Infectious Disease Review

A comprehensive set of question-and-answer flashcards covering homeostasis, nervous and endocrine regulation, non-infectious diseases, epidemiology, assistive technologies for sensory disorders, vision and kidney treatments, and disease-prevention strategies.

What is homeostasis?

The maintenance by an organism of a relatively constant internal environment despite external changes.

Why must internal conditions stay within narrow limits?

To ensure enzymes function at their optimum and metabolic efficiency is maintained.

What are tolerance limits?

The narrow range within which an internal variable (e.g., temperature, glucose) must be kept for survival.

Define set point in homeostasis.

The ideal or normal value around which a particular internal variable is regulated.

State the two broad stages of a negative feedback loop.

1) Detecting a change (stimulus) via receptors; 2) Counteracting the change via effectors to restore the set point.

List the five basic components of a negative feedback system.

Stimulus, Receptor, Control Centre, Effector, Response.

Which brain region commonly serves as the control centre for homeostatic regulation?

The hypothalamus.

What receptors detect changes in body temperature?

Thermoreceptors.

Where are thermoreceptors found?

In the skin and in the hypothalamus, where they monitor blood temperature.

Which part of the hypothalamus is the heat-gain centre?

The posterior (back) area.

Give three cooling responses triggered when body temperature rises.

Vasodilation, activation of sweat glands, reduced thyroxine release to lower metabolic rate.

Give four warming responses triggered when body temperature falls.

Vasoconstriction, hair erector contraction (piloerection), increased thyroxine via TSH, shivering.

What is vasodilation?

Dilation of blood vessels bringing blood closer to the skin surface, increasing heat loss.

What is vasoconstriction?

Narrowing of blood vessels to conserve heat by reducing blood flow to the skin.

Name the two major divisions of the nervous system.

Central Nervous System (CNS) and Peripheral Nervous System (PNS).

Describe the structure/function of sensory neurons.

Carry impulses from sensory receptors to the CNS; have a long dendron, cell body off to the side, and short axon.

Describe the structure/function of motor neurons.

Transmit impulses from the CNS to effectors; have short dendrites and a long axon.

Describe interneurons.

Neurons located within the CNS that connect sensory and motor neurons; short dendrites, variable axon length.

What are the two lobes of the pituitary gland?

Anterior and posterior lobes.

Which anterior-pituitary hormone controls growth?

Growth hormone (GH).

Which hormone is predominantly produced by the thyroid?

Thyroxine (T4).

What is the main role of parathyroid hormone?

To maintain blood calcium levels by acting on bones, intestines and kidneys.

Which pancreatic cells detect high blood glucose?

Beta cells of the islets of Langerhans.

What hormone do beta cells secrete?

Insulin.

What hormone do alpha cells secrete?

Glucagon, in response to low blood glucose.

Which part of the adrenal gland secretes cortisol?

The adrenal cortex.

Give two functions of cortisol.

Helps the body manage stress and regulates metabolism of carbohydrates, fats and proteins; also affects cardiovascular function and immunity.

Define a non-infectious disease.

A disease not caused by pathogens and not transmissible between individuals.

List four factors that influence the risk of non-infectious disease.

Age, genetics, lifestyle, environment (others include gender, socio-economic status, nutrition, culture).

What genetic mutation causes sickle-cell anaemia?

A mutation in the gene coding for haemoglobin.

Give one symptom of sickle-cell anaemia.

Fatigue, painful swelling of hands/feet, or frequent infections due to reduced oxygen transport.

What is an environmental disease?

A disease resulting from exposure to physical, chemical or lifestyle factors in the environment.

What exposure causes mesothelioma?

Inhalation of asbestos fibres leading to inflammation and tumour formation in the pleura.

What primary factor causes malignant melanoma?

Excessive exposure to ultraviolet (UV) radiation, often beginning with a cancerous mole.

What caused Minamata disease?

Mercury poisoning from contaminated fish and shellfish in Minamata Bay, Japan.

Differentiate undernutrition and overnutrition.

Undernutrition = insufficient intake of nutrients; overnutrition = excessive intake of food/nutrients.

Which vitamin deficiency leads to scurvy?

Vitamin C deficiency.

State two symptoms of scurvy.

Loose teeth, bleeding/bruising spots, hair loss, skin eruptions (any two).

What is a benign tumour?

A mass of abnormal cells that remains localized and does not invade other tissues.

What is a malignant tumour?

Cancerous cells that invade surrounding tissues and may spread (metastasize).

Define sarcoma.

Cancer arising in muscle, bone or connective tissue such as blood vessels.

Define carcinoma.

Cancer originating in epithelial tissues such as skin or organ linings.

Provide a concise definition of epidemiology.

The study of the distribution, determinants and control of health-related events in populations.

Name the three main types of epidemiological studies.

Descriptive, analytical and intervention studies.

List two criteria used to establish cause-and-effect in epidemiology.

High risk with exposure, consistency across studies, dose–response relationship, correct temporal sequence (any two).

State two advantages of epidemiological studies.

Identify disease causes & affected populations, guide public-health strategies, reveal environmental or lifestyle risk factors, contribute to genetic understanding (any two).

Differentiate conductive and sensorineural hearing loss.

Conductive: problem in outer/middle ear blocking sound; Sensorineural: damage to inner ear (hair cells) or auditory nerve.

Briefly explain how a cochlear implant restores hearing.

External processor converts sound to electrical signals sent to an implanted receiver; electrodes directly stimulate the cochlea, allowing the brain to perceive sound.

Give one benefit and one risk of cochlear implants.

Benefit: life-changing hearing for profoundly deaf; Risk: surgical complications/infection or high cost.

Who typically benefits from bone-conduction implants?

People with outer or middle-ear problems that block sound, such as collapsed ear canals.

How does a basic hearing aid function?

Microphone picks up sound, amplifier boosts it, receiver/speaker sends louder sound through the ear canal via the normal auditory pathway.

What structural defect causes myopia?

An eyeball that is too long so light focuses in front of the retina.

Which lens type corrects myopia?

Concave (diverging) lenses in spectacles or contacts.

How does laser eye surgery correct refractive errors?

A laser reshapes the cornea so light refracts correctly onto the retina.

Give two advantages of prescription spectacles.

Affordable and widely available; unlikely to cause side effects; easy replacement (any two).

Define osmoregulation.

Regulation of body water and salt concentrations.

Name the two vital functions of the kidneys.

Excretion of metabolic wastes and osmoregulation of water/salt levels.

What is one underlying cause of glomerulonephritis?

Inflammation of the kidney filters allowing proteins/RBCs to leak into urine.

What is haemodialysis?

A dialysis technique where a machine filters the patient's blood through a semi-permeable membrane outside the body.

Describe peritoneal dialysis in one sentence.

Dialysis fluid is introduced into the peritoneal cavity; wastes diffuse across the peritoneal membrane into the fluid, which is later drained.

List two public-health strategies for preventing non-infectious diseases.

Educational campaigns, screening programs, vaccination, genetic screening/engineering (any two).

What is gene therapy?

The insertion of normal, functioning genes into cells to correct genetic disorders.

How do HPV vaccines such as Gardasil prevent cervical cancer?

They elicit immunity against human papillomavirus strains that cause cervical and related cancers, preventing infection before exposure.

What is embryo pre-implantation genetic testing?

Screening IVF embryos for specific genetic diseases so only disease-free or carrier embryos are implanted.