ch.32

What are the levels of organization in animals?

Cells → tissues → organs → organ systems.

What are the 4 main types of animal tissue?

Epithelial, connective, muscle, and nervous tissue.

What is the main function of epithelial tissue?

It covers the body and lines body cavities; functions in protection, secretion, and absorption.

What is the main function of connective tissue?

It supports and cushions other body structures and contains cells scattered through an extracellular matrix.

What are the 3 types of muscle tissue?

Skeletal, cardiac, and smooth muscle.

What is the function of nervous tissue?

Receipt, processing, and transmission of information.

What is the difference between an organ and an organ system?

An organ contains multiple tissue types; an organ system is a group of organs working together for a specialized function.

What is the general role of organ systems?

Different organ systems perform specialized functions such as digestion, transport, gas exchange, defense, excretion, and regulation.

How do the nervous and endocrine systems differ?

The nervous system sends signals along specific neuron pathways, while the endocrine system sends hormones through the bloodstream.

Compare nervous and endocrine signaling.

Nervous signaling is fast and short-lasting; endocrine signaling is slower and longer-lasting.

What is the endocrine system?

A system of ductless glands that secrete hormones to regulate physiological processes.

How do hormones affect target cells?

Hormones travel in the blood and bind to specific receptors on or inside target cells.

How do lipid-soluble and water-soluble hormones differ?

Lipid-soluble hormones bind intracellular receptors; water-soluble hormones bind cell-surface receptors.

What is simple endocrine signaling?

An endocrine cell responds directly to a stimulus and releases a hormone into the blood.

What is neuroendocrine signaling?

A specialized neuron releases a hormone that travels to target cells.

What controls most endocrine activity?

The hypothalamus, which regulates the pituitary gland.

What does the posterior pituitary do?

It releases oxytocin and ADH that were produced by the hypothalamus.

What does the anterior pituitary do?

It secretes hormones that regulate growth, reproduction, metabolism, stress response, and other endocrine glands.

How does the hypothalamus regulate the anterior pituitary?

It releases releasing and inhibiting hormones that control anterior pituitary hormone secretion.

Can one hormone have multiple effects?

Yes; the same hormone can cause different responses in different tissues.

What is homeostasis?

The maintenance of a relatively steady internal environment around a set point.

What is negative feedback?

A response that counteracts a change and restores homeostasis.

What is positive feedback?

A response that intensifies a change and moves the system farther from homeostasis.

What is osmoregulation?

The regulation of water and solute concentrations in body fluids.

What is the difference between osmoconformers and osmoregulators?

Osmoconformers match their environment; osmoregulators use energy to control water uptake and loss.

How do freshwater and saltwater organisms differ in osmoregulation?

Freshwater organisms gain water and lose salts; saltwater organisms lose water and gain salts.

How do terrestrial animals prevent dehydration?

They reduce water loss with body coverings and gain water from drinking, food, and metabolism.

What are the main nitrogenous wastes?

Ammonia is toxic; urea and uric acid are less toxic but require more energy to produce.

What are the 4 major excretory processes?

Filtration, reabsorption, secretion, and excretion.

What is the path of urine through the urinary system?

Kidneys → ureters → urinary bladder → urethra.

What are the main functions of the kidneys?

They regulate fluid balance, filter blood, remove metabolic wastes, and help regulate blood pressure.

What is the nephron?

The functional unit of the kidney made of Bowman’s capsule, renal tubules, Loop of Henle, distal tubule, and collecting duct.

What happens during filtration?

High pressure in the glomerulus pushes some plasma into Bowman’s capsule.

What enters glomerular filtrate?

Water and small solutes such as glucose, amino acids, and ions.

What happens in the proximal tubule?

Most useful substances are reabsorbed into the blood.

What happens in the descending limb of the Loop of Henle?

Water leaves through aquaporins, making the filtrate more concentrated.

What happens in the ascending limb of the Loop of Henle?

Salt leaves the filtrate, but water does not, so the filtrate becomes more dilute.

What happens in the distal tubule?

K+ can be secreted, NaCl can be reabsorbed, and ions help regulate pH.

What happens in the collecting duct?

Water is reabsorbed and the urine becomes more concentrated as it moves toward the renal pelvis.

What is the overall path of filtrate through the nephron?

Bowman’s capsule → proximal tubule → descending limb → ascending limb → distal tubule → collecting duct.

Why are kangaroo rats important in this chapter?

They produce extremely concentrated urine to conserve water.

What are the four key processes involved in urine production?

Filtration → reabsorption → secretion → excretion.

What happens during filtration?

Blood plasma is filtered from the glomerulus into Bowman’s capsule under high pressure.

What substances can pass through the filtration membrane?

Water and small solutes such as glucose, amino acids, and ions.

What happens during reabsorption?

Useful substances are returned from the filtrate to the blood, especially in the proximal tubule.

What happens in the descending limb of the Loop of Henle?

Water leaves the filtrate through aquaporins, making it more concentrated.

What happens in the ascending limb of the Loop of Henle?

Salt leaves the filtrate, but water cannot follow, making the filtrate more dilute.

What happens during secretion in the distal tubule?

K+ can be added to the filtrate, NaCl can be reabsorbed, and ion movement helps regulate pH.

What happens in the collecting duct?

More water is reabsorbed and the urine becomes more concentrated.

What is the detailed path of filtrate through the nephron?

Bowman’s capsule → proximal tubule → descending limb → ascending limb → distal tubule → collecting duct.

What is the path of urine out of the body?

Kidneys → ureters → urinary bladder → urethra.

Summarize urine production from start to finish.

Filtration occurs at the glomerulus/Bowman’s capsule, useful materials are reabsorbed in the proximal tubule, water leaves in the descending limb, salt leaves in the ascending limb, ions are fine-tuned in the distal tubule, and more water is reabsorbed in the collecting duct.

What type of epithelium is found on surfaces subject to physical forces or abrasion?

Stratified epithelium — it has multiple layers of cells that protect underlying tissues from friction, wear, and damage.

What type of epithelial tissue, found in the intestines, absorbs nutrients?

Simple columnar epithelium — a single layer of tall cells specialized for absorption and secretion. In the intestines, these cells often have microvilli that increase surface area for nutrient absorption.

What type of epithelial tissue in the lungs permits gas exchange by diffusion?

Simple squamous epithelium — it is only one thin layer of flat cells, so gases like O₂ and CO₂ can diffuse across it quickly.

What type of epithelial tissue lines kidney tubules?

Simple cuboidal epithelium — a single layer of cube-shaped cells specialized for absorption and secretion in the kidney tubules.