Human Biology Q&A

50 flashcards covering key concepts from the video notes.

What are the two main functions of the human digestive system?

Breaking down large food molecules into smaller usable molecules and absorbing them.

What are the two types of digestion and where does each primarily occur?

Mechanical digestion (physical breakdown) occurs mainly in the mouth and stomach; chemical digestion (enzyme-driven) occurs mainly in the small intestine.

Which enzyme in saliva initiates starch digestion?

Salivary amylase.

In the stomach, which acid begins protein digestion and activates pepsinogen?

Hydrochloric acid (HCl).

What enzyme is activated by HCl to digest proteins in the stomach?

Pepsin (from pepsinogen).

What enzyme aids digestion of milk protein in the stomach?

Rennin.

What is the stomach's typical pH range?

Approximately pH 2 to 3.

What are the two sphincters at the ends of the stomach called?

Cardiac sphincter at the top and pyloric sphincter at the bottom.

Where does most chemical digestion occur in the digestive tract?

In the small intestine.

What are the three main classes of nutrients digested and their end products?

Proteins → amino acids; Carbohydrates → monosaccharides (glucose); Fats → fatty acids and monoglycerides.

What are the fingerlike projections that line the small intestine and absorb nutrients?

Villi (with microvilli).

What organ produces bile and what is its role?

The liver produces bile, which emulsifies fats; bile is stored in the gallbladder and released into the small intestine.

Where is bile stored prior to release into the small intestine?

The gallbladder.

Which organ secretes pancreatic enzymes into the small intestine?

The pancreas (pancreatic amylase, proteases like trypsin/chymotrypsin, lipases).

What are the main functions of the large intestine?

Egestion, vitamin production (B, K, folic acid), and water reabsorption.

Where does gas exchange occur in the respiratory system?

In the alveoli of the lungs.

What carries oxygen in the blood and what carries carbon dioxide in the blood's buffering system?

Oxygen is carried by hemoglobin; carbon dioxide is carried dissolved in plasma as part of the carbonic acid-bicarbonate system.

What structure is mainly responsible for the regulation of breathing rhythm?

The medulla oblongata (medulla).

What are the three major brain structures associated with movement, coordination, and autonomic functions (cerebrum, cerebellum, medulla) and their roles?

Cerebrum – conscious mind and voluntary actions; Cerebellum – coordinates movement and balance; Medulla – autonomic functions like breathing and blood pressure.

What is the basic functional unit of the nervous system?

Neuron.

What is saltatory conduction?

Rapid conduction of nerve impulses jumping from one node of Ranvier to the next due to myelin sheath.

What is the difference between the central and peripheral nervous systems?

Central nervous system = brain and spinal cord; Peripheral nervous system = nerves branching to the rest of the body.

What is clonal selection in the immune system?

Antigens bind to specific B or T lymphocytes, causing them to clone and differentiate into plasma and memory cells.

What are the four human blood types?

A, B, O, and AB.

What is the Rh factor?

A protein on red blood cells; Rh positive if present, Rh negative if absent.

What is an allergy?

Over-sensitivity to a normally harmless antigen that triggers an antibody response.

What is anaphylaxis?

A severe allergic reaction with massive histamine release that can constrict airways; treated with antihistamines.

What is an autoimmune disease?

When white blood cells attack the body's own healthy cells; examples include multiple sclerosis, lupus, arthritis, and juvenile diabetes.

What is a vaccine?

A preparation containing an inactive form of a disease to stimulate memory B and T cells.

What are the two main types of hormones and how do they act?

Steroid (lipid-soluble) hormones diffuse through the membrane and act inside the cell; nonsteroidal/polypeptide hormones bind to surface receptors and use second messengers like cAMP.

What is the role of negative feedback in endocrine regulation?

Maintains homeostasis by reducing deviation from a set point (e.g., thyroxine, blood pressure).

What are the two main regulatory systems that release chemicals to maintain homeostasis?

The endocrine system and the nervous system.

What are the functional units of the kidney and their general structure?

Nephrons; include glomerulus, Bowman's capsule, tubule, loop of Henle, collecting duct.

What is filtration in the kidney?

Passive, nonselective diffusion of plasma into Bowman's capsule to form filtrate.

What is reabsorption in the kidney?

Reabsorption of water and solutes back into the blood from the tubules and loop of Henle.

What is secretion in the kidney?

Active uptake of substances into the tubules that were not filtered.

Name the male reproductive structures mentioned.

Testes, vas deferens, prostate gland, scrotum, urethra.

What is spermatogenesis and what hormones stimulate it?

Production of sperm; LH stimulates testosterone production, with FSH and testosterone supporting sperm production.

Where does fertilization occur in the female reproductive system?

In the oviduct (Fallopian tube).

What are the main parts of the female reproductive system described?

Ovary, oviduct/Fallopian tube, uterus, vagina, cervix, endometrium.

What are the two phases of the female reproductive cycle and what drives them?

Follicular phase (maturation and uterine lining buildup) and luteal phase (thickening from corpus luteum; if fertilization occurs, pregnancy maintenance).

What is oogenesis?

Production of ova; primary oocytes present before birth; meiosis I at puberty yields secondary oocytes monthly; meiosis II occurs at fertilization.

What are the three stages of embryonic development and the germ layers they form?

Cleavage, blastula, gastrulation; ectoderm (skin, nervous system), endoderm (viscera), mesoderm (muscle, blood, bones).

What are the three muscle types in mammals?

Smooth (involuntary), Skeletal (voluntary), Cardiac.

What is the Sliding Filament Theory?

Muscle contraction occurs as thick (myosin) and thin (actin) filaments slide past each other, increasing overlap in sarcomeres.

What attaches muscles to bones and what attaches bones to bones to form joints?

Tendons connect muscles to bones; ligaments connect bones at joints.

Name the major skeletal system divisions: appendicular vs axial skeleton.

Appendicular skeleton = limbs; axial skeleton = skull and trunk.

What are the main types of joints and one example for each?

Fibrous (no movement), Cartilaginous (connected by cartilage), Synovial (with cartilage cushions; e.g., ball-and-socket, hinge, pivot, saddle, condyloid).

Which eye cells distinguish colors and contribute to color vision?

Cones.

Which eye structures protect, refract, and focus light onto the retina?

Cornea protects and allows light entry; lens focuses light; iris controls light entry; pupil is the opening.

What part of the eye converts light into nerve impulses?

Retina.

What is the other type of photoreceptor in the eye besides cones and its characteristic?

Rods; extremely sensitive but color-insensitive (black & white vision).

What are the components of the ear involved in hearing and balance?

Auditory canal, cochlea, the ossicles (hammer, anvil, stirrup), Eustachian tube, oval window, and semicircular canals.