Human Biology Sem 1 Exam

Homeostasis

Maintenance of a stable internal environment within cells.

Why do the ventricles have higher pressure during atrial filling?

During atrial filling chambers contract, causing blow flow into the arteries.

Cell membrane

The outer boundary of the cell.

Organelles

Structures suspended in the cytoplasm that carry out particular functions.

Cytosol

The liquid part of the cytoplasm.

Cytoskeleton

Internal scaffolding of protein fibres within the cytoplasm.

Inclusions

Chemical substances occurring as granules or liquid droplets in the cytoplasm.

Diffusion

Movement of molecules from high to low concentration.

Cytoplasm

Those parts of the cell within the cell membrane, except for the nucleus.

Osmotic Pressure

The amount of force applied to a solution that prevents solvent from moving across a semipermeable membrane.

Osmosis

Diffusion of water across a semi-permeable membrane.

Facilitated Diffusion

Uses carrier proteins for passive transport.

Hypotonic Solutions

Has a lower concentration of solutes compared to another solution it is being compared to.

Organization Levels

Cells → Tissues → Organs → Organ Systems → Organism.

Differentiation

Process where cells become specialized for specific functions.

Epithelial Tissue

Covering/lining tissue; thin & flat or cylindrical or cuboidal; tightly packed cells; acts as coverings; found in the outer layer of skin and lines inside of organs.

Connective Tissue

Separated from each other by large amounts of material not made up of cells (matrix)

Examples of connective tissue

Blood, bones, tendons, ligaments, cartilage

Nervous Tissue

Made of neurons- nerve cells

Muscular Tissue

Responsible for movement of body parts

Skeletal Muscle

Long & thin, striated, voluntary muscle with peripheral nucleus

Involuntary Muscle (Smooth Muscle)

Long & thin, non-striated, non-voluntary muscle with central nucleus

Cardiac Muscle

Long & thin, striated, non-voluntary muscle with central nucleus

Metabolism

The chemical processes that occur within a living organism in order to maintain life

Anabolism

Building complex molecules from simpler ones (requires energy)

Catabolism

Breaking down complex molecules into simpler ones (releases energy)

Nutrients

Organic (e.g., carbohydrates, proteins, lipids) and inorganic (e.g., water, minerals)

Enzymes

Catalysts that allow reactions to occur at normal body temp

Activation Energy

Energy required to start a reaction

Substrate

Molecule on which an enzyme acts

Lock-and-Key Model

Substrate fits enzyme like a key in a lock

Induced Fit Model

Enzyme adjusts shape to fit substrate

Cellular Respiration

Process by which organic molecules are broken down to produce energy in the form of ATP

Glycolysis

Breaks down glucose & produces 2 ATP molecules & 2 pyruvic acid molecules

Aerobic Respiration

CR with oxygen, occurs in the mitochondria, producing up to 36 ATP molecules

Anaerobic Respiration

CR without oxygen, occurs in the cytoplasm, producing lactic acid if no oxygen is present

ATP/ADP Cycle

ATP stores energy; breaking its bonds releases energy for cellular processes

Respiratory System

Composed of the nose, pharynx, larynx, trachea, bronchi, bronchioles, and lungs

Inspiration

The diaphragm and external intercostal muscles contract, expanding the chest cavity and creating a lower pressure within the lungs. The thoracic cavity and lung volume increase.

Expiration

The diaphragm and intercostal muscles relax, causing the chest cavity to decrease in size and the lungs to deflate.

Gas Exchange (GE)

Exchange of oxygen and carbon dioxide in the lungs.

Where does GE occur?

Between the alveoli and surrounding capillaries.

When does GE occur?

All the time except when alveoli are damaged by respiratory conditions like - emphysema, cancer, TB (tuberculosis).

Why does GE occur?

It allows oxygen to enter the blood supply and be delivered to the cells to be used in the process of cellular respiration.

How does GE occur?

Due to structural adaptations and a concentration gradient

Structural Adaptations

Alveoli give the lungs a large surface area to increase the rate of GE.

Continuous flow of blood

Each alveolus is well supplied with blood vessels (capillaries) with a continuous flow of blood.

Movement of air

Movement of air in & out of lungs by the intercostal muscles and diaphragm also maintain the O2/CO2 concentration gradient.

Alveolus and capillary thickness

Alveolus and capillary are only one cell thin, so O2/CO2 do not have far to diffuse.

Lung positioning

The lungs are positioned deep inside the body to prevent evaporation of moisture that lines the alveolus.

Thin layer of moisture

Thin layer of moisture between alveolus and capillaries increases the rate of GE.

Concentration Gradient

There must be a concentration gradient so the gases can diffuse across the alveoli and capillary wall.

Oxygen movement

O2 moves from high concentration in alveoli into low concentration in blood.

Carbon dioxide movement

CO2 moves from high concentration in blood to low concentration in alveoli.

Effects on GE

Diseases like emphysema, lung cancer, asthma, and infections impair gas exchange by damaging lung tissue or narrowing airways.

Components of CS

Made up of blood, heart and blood vessels.

Function of CS

Transport nutrients, oxygen, water, white blood cells, hormones to every cell in the body.

Maintenance by CS

Maintain pH, maintain body temp, maintain H2O/ion (electrolyte) concentration.

Protection by CS

Against disease/invading microorganisms, blood clotting to prevent blood loss.

Blood composition

Plasma, erythrocytes, leucocytes, and thrombocytes.

Plasma

A solution primarily composed of water, containing dissolved solutes such as glucose and electrolytes.

Erythrocytes (Red Blood Cells)

Exhibit a biconcave disc shape, lacking a nucleus to enhance flexibility and facilitate passage through capillaries.

Leucocytes (White Blood Cells)

Essential for immune defence mechanisms, representing about 1% of blood volume.

Thrombocytes (Platelets)

Small, anucleate cell fragments that adhere to damaged endothelium and initiate the coagulation cascade.

Blood Clotting

Also called coagulation, it is the process that occurs when there is injury or damage to blood vessels.

Haemostasis

The process of stopping bleeding.

Clot

A plug of platelets, WBCs, RBCs, and plasma trapped in fibrin.

Fibrin

A protein in the form of threads that form a mesh to create a clot (thrombus) and keeps the clot attached to the wall of the blood vessel.

Vasoconstriction

The constriction (narrowing) of blood vessels at the injury site to reduce blood flow to the area.

Vasoconstrictors

Chemicals released by platelets that cause vasoconstriction.

Clotting Factors (CF)

Chemical substances in the blood that strengthen and reinforce the clot, releasing fibrin.

Clot Retraction

The process where fibrin contracts and pulls the edges of the blood vessel together.

Serum

The fluid that is squeezed out during clot retraction.

Scab Formation

The process of a dried-out clot forming over a wound.

Oxygen (O2) Transport

3% of O2 is transported in plasma, while 97% is combined with haemoglobin (oxyhaemoglobin).

Haemoglobin

A protein in RBCs that binds oxygen in the lungs and releases it in tissues.

Carbon Dioxide Transport

About 70% of carbon dioxide is converted to bicarbonate ions in RBCs and transported in plasma.

Flow of Blood through the Heart

The right atrium receives blood from the body and passes it to the right ventricle, which pumps blood to the lungs; the left atrium receives blood from the lungs and passes it to the left ventricle, which pumps blood to the body.

Arteries and Arterioles

Have thick, muscular, and elastic walls to withstand and regulate high-pressure blood flow from the heart to tissues.

Veins and Venules

Have thinner walls and valves to prevent backflow, carrying low-pressure blood back to the heart.

Capillaries

Very thin walled (one cell thick) to allow efficient exchange of gases, nutrients, and wastes between blood and tissues.

Blood flow

Fastest and under highest pressure in arteries, slows in capillaries for exchange, and returns at low pressure in veins.

Cardiac Cycle Phases

Diastole (heart muscle relaxes, and chambers fill with blood) and Systole (heart muscle contracts and pumps blood out to the arteries).

Cardiac Output

The volume of blood the heart pumps per minute, calculated as heart rate × stroke volume.

Blood Types

Determined by specific antigens on the surface of red blood cells, classified by the ABO system and the Rh factor.

Type A Blood

Has A antigens and anti-B antibodies.

Type B Blood

Has B antigens and anti-A antibodies.

Type AB Blood

Has both A and B antigens, no anti-A or anti-B antibodies.

Type O Blood

Has no A or B antigens, but has both anti-A and anti-B antibodies.

Rh Factor

Determines if blood type is Rh-positive (+) or Rh-negative (-), based on the presence of the Rh antigen.

Universal Donor

O negative blood type

Universal Recipient

AB positive blood type

Lymphatic System Functions

To collect fluid that escapes from blood capillaries and return it to the circulatory system, and to defend the body against pathogens.

Lymph

Excess fluid from the blood, originally plasma, then interstitial fluid, then lymph.

Oedema

Swelling caused by the accumulation of fluid between cells.

Mechanical Digestion

Physical breakdown of food, including chewing and churning.

Chemical Digestion

Enzymes break complex molecules into simple ones.

Stages of digestion

Ingestion, Mastication, Mechanical digestion, Chemical digestion, Peristalsis, Segmentation, Absorption, Elimination.

Digestive System Structure

A tube (alimentary canal) with organs (mouth, oesophagus, stomach, intestines) and glands (salivary, pancreas, liver, gall bladder) that aid digestion and absorption.

Mouth

Ingestion, chewing (teeth), saliva (amylase) starts starch digestion.