biology midterm exam

Types of Tissues

Epithelial Tissue

  • Definition: Forms the outer covering of the skin and lines body cavities.

  • Functions: Protection, absorption, secretion, filtration, sensation.

  • Types:
      - Simple squamous
      - Simple cuboidal

Muscle Tissue

  • Definition: Found in muscles; controls movement.

  • Functions: Movement, posture, heat production.

  • Types:
      - Cardiac Muscle: Involuntary, found in the heart.
      - Smooth Muscle: Involuntary, found in blood vessels.
      - Skeletal Muscle: Voluntary, connected to bones.

Connective Tissue

  • Definition: Connects, supports, and binds other tissues.

  • Examples:
      - Ligament: Connects bone to bone.
      - Tendon: Connects muscle to bone.
      - Types include blood, loose connective, adipose fat, cartilage, and dense connective tissue.

Nervous Tissue

  • Definition: Made up of neurons and glial cells; receives stimuli and transmits electrical impulses.

  • Functions: Conducts signals for communication, regulates body functions.

Teeth and Their Functions

  • Tooth Types:
      - Incisors: Cutting
      - Canines: Tearing
      - Premolars: Crushing
      - Molars: Grinding

  • Peristalsis: Wave-like contraction and relaxation of the muscular wall of the alimentary canal to move food forward and mix and crush it. Occurs throughout the digestive system.

Stages of Digestion

  1. Ingestion: Occurs in the mouth (pH 7-7.2)
       - Mechanical Digestion: Teeth break food into smaller pieces.

  2. Chemical Digestion: Breakdown of complex molecules into simple molecules using enzymes.

Nutrient Absorption

  • Location: Primarily in the ileum, where the inner lining has villi to increase surface area for absorption.

  • Components of a Villus:
      - Capillaries: Absorb glucose, amino acids, minerals.
      - Lacteals: Absorb glycerol and fatty acids.

  • Water absorption: Primarily occurs in the small intestine; remaining water is absorbed in the large intestine.

Assimilation

  • Definition: Absorbed nutrients are utilized by cells for various processes:
      - Glucose: Used in respiration to produce ATP.
      - Amino Acids: Used for protein synthesis.
      - Lipids: Used in cell membranes and hormone production.

Digestion Process

Associated (Accessory) Organs

  • Organs: Salivary glands, liver, pancreas, gall bladder; all release digestive juices.

Human Digestive System Components

  • Main Components: Alimentary Canal (Mouth → Oesophagus → Stomach → Small intestine → Large intestine → Rectum → Anus).

Homeostasis

  • Definition: The ability to maintain a stable internal environment despite external changes.

  • Nutritional Role: Nutrition supplies energy and raw materials vital for homeostasis.

  • Temperature Regulation:
      - Cold Environment: Hypothalamus senses temperature drop, signals for heat production (shivering).
      - Warm Environment: Hypothalamus senses temperature rise, triggers cooling mechanisms (sweating).

Balanced Diet

  • Definition: Contains all required nutrients in appropriate proportions, provides correct energy amounts.

  • Essential Nutrients:
      1. Carbohydrates
      2. Proteins
      3. Fats and oils
      4. Vitamins
      5. Mineral ions
      6. Water
      - Dietary Fiber: Important for healthy digestion.

Chemical Digestion

  • Saliva: Contains amylase enzyme that breaks down starch into maltose.

  • Stomach:
      - Structure: Muscular sac that churns food into chyme.
      - Gastric Juice Contains:
        - Hydrochloric acid (HCl): Creates acidic environment, activates pepsinogen to pepsin, kills bacteria, halts salivary amylase activity.

Types of Digestion

  • Mechanical Digestion: Breaks food into smaller pieces without chemical change.
      - Occurs in: Teeth and stomach muscles.

  • Chemical Digestion: Uses enzymes to break complex molecules into simpler forms.

Absorption of Nutrients

  • Digestive Juices: Pancreatic juice neutralizes HCl, digests fats using lipase, and proteins using trypsin.

  • Villi: Increase surface area of the intestinal walls for efficient nutrient absorption.

  • Components and Functions:
      - Amylase: Breaks down starch into maltose.
      - Trypsin: Converts proteins into peptides.
      - Lipase: Breaks down fats into fatty acids and glycerol.

Summary of Digestion Locations

  • Mouth: Mechanical (chewing) and chemical (amylase) digestion.

  • Stomach: Mechanical (churning) and chemical (pepsin) digestion.

  • Small Intestine: Mixing and action of amylase, trypsin, lipase.

Egestion

  • Definition: The removal of undigested food, dead cells, and waste materials through the rectum to the anus.

Nutrient Deficiencies

  • Vitamin C (Scurvy): Symptoms include bleeding gums and loose teeth.

  • Vitamin D: Results in rickets, soft bones, bowed legs.

  • Iron: Causes anemia, fatigue, and weakness.

  • Calcium: Deficiency leads to osteoporosis and weak bones.

Key Terms

  • General Definitions:
      - Tissue: Specialized cells performing a common function.
      - Organ: A structure composed of different tissues working together.
      - Organ System: A group of organs that work together.
      - Organism: An individual living being potentially comprised of one or more organ systems.

Germ Layers Development

  • Ectoderm: Develops into skin, nervous system, and related structures.

  • Mesoderm: Gives rise to connective tissues, muscles, and the circulatory system.

  • Endoderm: Forms linings of the digestive and respiratory systems, and related organs.