Circulation and Gas Exchange/
Osmoregulation and Excretion

Vocab

Arteries

Blood vessels that deliver oxyen-rich blood from the heart to the tissues of the body

Arterioles

Transports blood from arteries to capillaries

Venules

Allow blood to return to the veins

Veins

Carry oxygen-depleted blood toward the heart

Capillaries

Smallest of blood vessels

Transfer oxygen and nutrients from the bloodstream to other tissues in the body

Single Vs Double Circulation

Single Circulation

Blood passes through the heart once in each complete circuit through the body

Blood entering the heart collects in the atrium before transfer to the ventricle

Blood that leaves the heart passes through two capillary beds before returning to the heart - when blood flows through the capillary beds, blood pressure drops

Double Circulation

Pumps for the two circuits are combined into the heart and simplifies coordination of the pumping cycles

The right side of the heart delivers oxygen-poor blood to the capillary beds of the gas exchange tissues where oxygen moves IN and carbon dioxide moves OUT

  • called pulmonary circuit if capillary beds are in the lungs
  • called pulmocutaneous circuit if it includes capillaries in both the lungs and the skin (amphibians)

After the oxygen-rich blood leaves the gas exchange tissues, it enters the other pump, the left side of the heart

After exchanging the carbon dioxide and the oxygen, the blood returns to the heart and completes the systemic circuit

The Heart

Systole

The phase of the heartbeat when the heart muscle contracts and pumps blood from the chambers into the arteries

Diastole

Phase of the heartbeat when the heart muscle relaxes and allows the chambers to fill with blood

Cardiac Cycle

Refers to the mechanical and electrical events that repeats with every heartbeat

Cardiac Output

The product of two variables: stroke volume and heartbeat

Heartbeat is the number of times a heart beats per minute while stroke volume is the amount of blood circulated by the heart with each beat

CO = SV X HR

ECG/EKG

Electrocardiograms that measure electrical activity and collect data on the health of your heart. Measures heart rate, stress, fatigue, heart age, breathing index, and mood

Bundle Branches - part of the electrical system of the heart. It directs the impulse to the left and right ventricles

Purkinje fibers are a unique cardiac end-organ. It receives conductive signals originating at the atrioventricular node and simultaneously activates the left and right ventriclces by directly stimulating the ventriclar myocardium

Sinoatrial node is a small boy of muscle tissues in the wall of the right atrium that acts as a pacemaker by producing a contractile signal at regular intervals

Atrioventricular node takes the signal from the SA node and then sends the electrical impulses from the atria to the ventricles

Artery Vs Vein

Arteries have thick, elastic, muscular walls

Veins have thin walls with few elastic fibers and one-way valves whereas arteries do not have any

the thicker and more muscular walls of arteries help them to withstand and absorb the pressure waves which begin in the heart and are transmitted to the blood

Veins convey blood back to the heart at a lower pressure so that they don't require thick walls. Vein uses its valves to redirect flow of blood to the heart

Blood Pressure

Measured by beats/min

Normal is 120/80 mm Hg

Usually lowest at nighttime when you're sleeping then it rises for a few hours before you wake up and continues to rise throughout the day. Reaches its peak in the middle of the afternoon then begins dropping again

Hypertension is 140/90!!!

Capillaries

Transfer oxygen and other nutrients from the bloodstream to other tissues and the body

Only one cell thick

Because it lacks smooth muscle - blood flow is altered by constriction or dilation of the arterioles that supply capillary beds or opening and closing precapillary sphincters

Blood Composition

Plasma

Liquid matrix

Blood electrolytes

The proteins called albumins act as a buffer against pH changes and help maintain the osmotic balance between blood and interstitial fluid

Fibrinogens which are clotting factors that help plug leaks when blood vessels are injured

Erthyrocytes

Red blood cells - most numerous

Main function is to transport oxygen

Round discs to increase surface area

Hemoglobin are iron-containing protein that transports oxygen

Leukocytes

White blood cells that fight infection

Phagocytes, B cells, and T cells

Platelets

Specialized bone marrow cells

Atherosclerosis

Hardening of the arteries by accumulation of fatty deposits

Results of high ratios of LDL and HDL

Causes damage to the arterial lining and results in inflammation. Plaque begins to grow and the walls of the arteries become thick and stiff. A thrombus can form in the artery if the plaque ruptures

Can lead to a heart attack or stroke

Gas Exchange

When food is swallowed, the larynx moves upward and tips the epiglottis over the glottis which opens the trachea/windpipe

Air then passes through

Branches into two bronchi

Bronchioles

Mucus escalator

Alveoli (air sacs)

oxygen enters the alveoli and diffuses across the capillaries

Osmoregulation

General term for the processes by which animals control solute concentrations and balance water loss and gain.

Execretion

Process that rids the body of nitrogenous metabolites and other metabolic waste products

Osmolarity

The number of moles of solute per liter of solution

Osmosis

How water enters and leaves cells

Occurs when two solutions separated by a membrane differ in total solute concentration

Osmoregulator

Osmoconformer

Being isoosmotic with its surroundings

Control internal osmolarity independent of that of the external environment

Marine animals

Allows them to live in environments that are uninhabitable

Excretory Processes

Filtration

Water and small solutes corss the membrane forming a solution called filtrate

converted into a waste fluid --- called reabsorption which recovers useful molecules and water from the filtrate and returns them to the body fluid

nonessential solutes and wastes are left in the filtrate and are added to secretion which occurs through active transport

Nephron

Proximal tubule: reabsorption

Descending limb of the loop of Henle

Reabsorption of water continues as the fltrate moves into the descending limb of the loop of Henle

Ascending limb of the loop of Henle

Filtrate reaches the tip of the loop and then returns to the cortext in the ascending limb

Distal tubule

Collecting Duct

Homeostatic Regulation of the Kidney

ADH (antidiuretic hormone)

Vasopressin

When osmolarity rises, ADH release into the bloodstream also increases

In the kidney, ADH makes the epithelium more permeable to water

Thus, it increases water reabsorption in water, reduces urine volume, and lowers blood osmolarity back toward the set point

Mutations

ADH receptor gene inactivated

Causes severe dehydration and solute imbalance

The RAAS

JGA, a specialized tissue consisting of cells of and around the afferent arteriole which supplies blood to the glomerulus

whenever blood pressure or volume drops in the afferent arteriole then the JGA releases the enzyme renin

This initates angiotensinogen

Raises blood pressure by constricting arterioles